K103603 · Zeus Scientific, Inc. · MYF · May 20, 2011 · Microbiology
Device Facts
Record ID
K103603
Device Name
ZEUS ELISA HSV GG-2 IGG TEST SYSTEM
Applicant
Zeus Scientific, Inc.
Product Code
MYF · Microbiology
Decision Date
May 20, 2011
Decision
SESE
Submission Type
Traditional
Regulation
21 CFR 866.3305
Device Class
Class 2
Indications for Use
The ZEUS ELISA HSV gG-2 IgG Test System is intended for the qualitative detection of type specific IgG class antibodies to Herpes Simplex Virus Type 2 (HSV-2) in human serum. The test is intended for testing sexually active individuals or pregnant women for aiding in the presumptive diagnosis of HSV-2 infection. The predictive value of positive or negative results depends on the population's prevalence and the pretest likelihood of HSV-2. The test is not intended for donor screening or for self testing. The performance of this assay has not been established for use in a pediatric population, neonates, or immunocompromised patients.
Device Story
ZEUS ELISA HSV gG-2 IgG Test System is an enzyme-linked immunosorbent assay (ELISA) for qualitative detection of IgG antibodies to HSV-2 glycoprotein G (gG-2) in human serum. Device uses polystyrene 96-well plates sensitized with affinity-purified HSV-2 native antigen. Patient serum is incubated in wells; antigen-specific IgG binds to immobilized antigen. After washing, horseradish peroxidase-conjugated goat anti-human IgG (Fc-specific) is added. Following further incubation and washing, peroxidase substrate (TMB) is added, causing color change proportional to bound antibody. Reaction is stopped and optical density measured via spectrophotometer. Results are interpreted against a cutoff value (Index Value <= 0.90 negative; 0.91-1.09 equivocal; >= 1.10 positive). Used in clinical laboratories by trained personnel to aid in HSV-2 diagnosis. Output assists clinicians in evaluating patient infection status based on clinical history and epidemiological data.
Clinical Evidence
No clinical data provided in the summary document; substantial equivalence is based on analytical performance characteristics and comparison to the predicate device.
Technological Characteristics
Immunoassay (ELISA) using affinity-purified HSV-2 native antigen on polystyrene 96-well plates. Detection via horseradish peroxidase-conjugated goat anti-human IgG (Fc-specific) and TMB substrate. Requires spectrophotometer for optical density measurement. Qualitative interpretation based on index values. No automated software algorithm; manual or instrument-assisted photometric reading.
Indications for Use
Indicated for sexually active individuals or pregnant women to aid in the presumptive diagnosis of HSV-2 infection. Not for pediatric, neonatal, or immunocompromised populations.
Regulatory Classification
Identification
Herpes simplex virus serological assays are devices that consist of antigens and antisera used in various serological tests to identify antibodies to herpes simplex virus in serum. Additionally, some of the assays consist of herpes simplex virus antisera conjugated with a fluorescent dye (immunofluorescent assays) used to identify herpes simplex virus directly from clinical specimens or tissue culture isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by herpes simplex viruses and provides epidemiological information on these diseases. Herpes simplex viral infections range from common and mild lesions of the skin and mucous membranes to a severe form of encephalitis (inflammation of the brain). Neonatal herpes virus infections range from a mild infection to a severe generalized disease with a fatal outcome.
Special Controls
*Classification.* Class II (special controls). The device is classified as class II (special controls). The special control for the device is FDA's revised guidance document entitled “Class II Special Controls Guidance Document: Herpes Simplex Virus Types 1 and 2 Serological Assays.” For availability of the guidance revised document, see § 866.1(e).
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
A. 510(k) Number: K103603
B. Purpose for Submission: Clearance of New Device
C. Measured: Herpes Simplex Virus HSV-2 type specific IgG antibodies to the affinity purified HSV glycoprotein G (gG) 2 native antigen
D. Type of Test: Enzyme-linked Immunosorbent Assay (ELISA)
E. Applicant: Zeus Scientific, Inc.
F. Proprietary and Established Names: ZEUS ELISA HSV gG-2 IgG Test System
## G. Regulatory Information:
1. Regulation section: 21 CFR 866.3305. Herpes Simplex Virus Serological Reagents
2. Classification: Class II
3. Product code: MYF, Enzyme linked immunosorbent assay, Herpes Simplex Virus, HSV-2
4. Panel: Microbiology (83)
## H. Intended Use:
1. Intended use(s):
The ZEUS ELISA HSV gG-2 IgG Test System is intended for the qualitative detection of type specific IgG class antibodies to Herpes Simplex Virus Type 2 (HSV-2) in human serum. The test is intended for testing sexually active individuals or pregnant women for aiding in the presumptive diagnosis of HSV-2 infection.
The predictive value of positive or negative results depends on the population's prevalence and the pretest likelihood of HSV-2. The test is not intended for donor screening or for self testing.
The performance of this assay has not been established for use in a pediatric population, neonates, or immunocompromised patients.
2. Indication(s) for use:
Same as Intended Use
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3. Special conditions for use statement(s):
For prescription use only
4. Special instrument requirements:
Spectrophotometer
I. Device Description:
The ZEUS ELISA HSV gG-2 IgG Test System is an immunoassay for the qualitative detection of IgG antibodies to HSV glycoprotein G (gG) 2 in human serum. The test system consists of affinity purified HSV-2 native antigen and horse radish peroxidase conjugated goat anti-human IgG (Fc chain specific) to detect IgG class antibodies to HSV-2 in human sera.
J. Substantial Equivalence Information:
1. Predicate device name(s): Reference Method for clinical evaluation
HerpeSelect® 1 and 2 Immunoblot IgG (Focus Diagnostics)
2. Predicate Numbers (s): K000238
Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | ZEUS ELISA HSV gG-2 IgG | Focus HerpeSelect 1 and 2 Immunoblot IgG |
| Intended Use | The ZEUS ELISA HSV gG-2 IgG Test System is intended for the qualitative detection of type specific IgG class antibodies to HSV-2 in human serum. The test is intended for testing sexually active individuals or pregnant women for aiding in the presumptive diagnosis of HSV infection. The predictive value of positive or negative results depends on the population's prevalence and the pretest likelihood of HSV-2. The test is not intended for donor screening or for self testing. The performance of this assay has not been established for use in a pediatric population, neonates, or immunocompromised patients. | Focus Diagnostics' HerpeSelect 1 and 2 Immunoblot IgG test is intended for qualitatively detecting the presence or absence of human IgG class antibodies to HSV-1 and HSV-2 in human sera. The test is indicated for testing sexually active adults or pregnant women for aiding in the presumptive diagnosis of HSV-1 and HSV-2 infection. The predictive value of a positive or negative result depends on the population's prevalence and the pretest likelihood of HSV-1 and HSV-2 infection. The performance of this assay has not been established for use in a pediatric population, for neonatal screening, for testing of immunocompromised patients, for use by a point of care facility or for use with automated equipment. |
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| Assay | Immunoassay | Immunoassay |
| --- | --- | --- |
| Sample Matrix | Human Serum | Human Serum |
| Analyte | Human IgG | Human IgG |
| Conjugate | Goat anti-human IgG; Fc chain specific | Goat anti-human IgG; Fc chain specific |
| Controls | 2 (Negative and Positive) | 2 (Negative and Positive) |
| Differences | | |
| Item | ZEUS ELISA HSV gG-2 IgG | Focus HerpeSelect 1 and 2 Immunoblot IgG |
| Detection Method | Colorimetric | Visual |
| Solid Phase | Polystyrene 96 well plate | Nitrocellulose membrane |
| Substrate | TMB | Bromo-chloro-indolyl phosphate and nitroblue tetrazolium/A |
| Conjugate Label | Horseradish peroxidase | Alkaline phosphatase |
| Calibrators | Includes Calibrator (human serum) | Cutoff/Positive control |
| Reading | Read the color change (optical density) of the wells | Visually compare each band on a strip relative to the control band four bands per strip |
| Detection HSV type | HSV-2 IgG only | HSV-1 IgG and HSV-2 IgG |
| Antigen Used | HSV gG-2 native antigen | Recombinant and native HSV gG-1 and gG2 antigen |
| Interpretation Criteria | Negative is <= 0.90, Positive is >= 1.10 and Equivocal is 0.90 - 1.09 | If patient band equal or darker than control band, result is positive. If band is lighter than control band, result is negative |
# K. Standard/Guidance Documents Referenced (if applicable):
1. Class II Special Controls Guidance Document: Herpes Simplex Virus Types 1 & 2 Serological Assays, September 28, 2010. http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm227411.htm
2. CLSI EP5: Evaluation of Precision Performance of Clinical Chemistry Devices-Second Edition, Villanova PA
3. CLSI EP7-A2: Interference Testing in Clinical Chemistry; Approved Guideline, 2nd Ed. (2005).
# L. Test Principle:
The ZEUS ELISA HSV gG-2 test system is designed to detect IgG class antibodies to HSV-2 in human sera. Wells of plastic microwell strips are sensitized by passive adsorption with affinity purified HSV-2 native antigen. The test procedure involves three incubation steps:
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1. Test sera (properly diluted) are incubated in antigen coated microwells. Any antigen specific antibody in the sample will bind to the immobilized antigen. The plate is washed to remove unbound antibody and other serum components.
2. Peroxidase Conjugated goat anti-human IgG (Fc chain specific) is added to the wells and the plate is incubated. The Conjugate will react with IgG antibody immobilized on the solid phase in step 1. The wells are washed to remove non-reactive Conjugate.
3. The microwells containing immobilized peroxidase Conjugate are incubated with peroxidase Substrate Solution. Hydrolysis of the Substrate by peroxidase produces a color change. After a period of time, the reaction is stopped and the color intensity of the solution is measured photometrically. The color intensity of the solution will be greater than the cutoff value if anti-HSV-2 IgG is present in the serum being tested.
# M. Performance Characteristics (if/when applicable):
# 1. Analytical performance:
# a. Precision/Reproducibility:
Precision was evaluated internally at Zeus Scientific. The study was conducted as follows: twelve samples were identified and/or prepared (by Zeus Scientific, Inc.) for use in the study based upon their activity on the ZEUS ELISA HSV gG-2 kit. Two samples each were selected that were negative, high negative, near cut-off, low positive, moderate positive and high positive. On each day of testing, the samples were aliquoted in duplicate and tested. This was repeated in a second run on the same day by a different technologist for a total of twenty days (2 replicates x 2 runs/day x 20 days = 80 replicates per sample). The precision data were analyzed according to the principles described in the Clinical Laboratory Standards Institute guidance EP5-A2, revised November 2004. The standard deviation (SD) and percent coefficient of variation (%CV) were calculated. Results are shown in Table 1.
Table 1. Summary of In-house Precision HSV gG-2 IgG
| Panel Member | Sample N | Mean IV | Within-Run | | Within-Day | | Between-Run | | Total | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| High Positive | 80 | 9.096 | 0.22 | 2.4% | 0.34 | 3.7% | 0.29 | 3.2% | 0.41 | 4.5% |
| High Positive | 80 | 5.290 | 0.12 | 2.3% | 0.19 | 3.5% | 0.15 | 2.9% | 0.25 | 4.6% |
| Mod Positive | 80 | 2.512 | 0.06 | 2.5% | 0.11 | 4.3% | 0.10 | 4.1% | 0.15 | 5.9% |
| Mod Positive | 80 | 2.308 | 0.07 | 3.0% | 0.10 | 4.3% | 0.09 | 3.9% | 0.12 | 5.3% |
| Low Positive | 80 | 1.377 | 0.06 | 4.5% | 0.07 | 5.2% | 0.04 | 3.3% | 0.08 | 6.0% |
| Low Positive | 80 | 1.288 | 0.05 | 4.0% | 0.07 | 5.1% | 0.04 | 3.3% | 0.09 | 6.7% |
| Near Cut-off | 80 | 1.028 | 0.03 | 3.0% | 0.05 | 5.0% | 0.05 | 4.7% | 0.06 | 6.0% |
| Near Cut-off | 80 | 0.992 | 0.03 | 2.9% | 0.05 | 4.6% | 0.04 | 3.9% | 0.06 | 6.1% |
| High Negative | 80 | 0.702 | 0.02 | 3.3% | 0.03 | 4.6% | 0.02 | 3.4% | 0.04 | 5.8% |
| High Negative | 80 | 0.663 | 0.03 | 3.9% | 0.03 | 5.3% | 0.02 | 3.8% | 0.05 | 7.5% |
| Negative | 80 | 0.205 | 0.01 | 5.2% | 0.02 | 7.6% | 0.01 | 6.6% | 0.02 | 10.2% |
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Reproducibility was evaluated internally and at two external clinical sites. The study was conducted as follows: twelve samples were identified and/or prepared (by Zeus Scientific, Inc.) for use in the study based upon their activity on the ZEUS ELISA HSV gG-2 IgG test system. Two samples each were selected that were negative, high negative, near cut-off, low positive, moderate positive and high positive. To assess reproducibility, on each day of testing, each sample was aliquoted in duplicate, each aliquot was tested in triplicate in two runs by two operators resulting in twelve results per day. This was repeated for five days at each site and the resulting data used for analysis (3 replicates x 4 runs/day x 5 days x 3 sites = 180 replicates per sample). Results are shown in Table 2.
Table 2. Summary of Multi-Site Reproducibility HSV gG-2 IgG
| Panel Member | Sample N | Mean IV | Within-Run | | Within-Day | | Between-Run | | Between-Site | | Total | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| High Positive | 180 | 8.270 | 0.33 | 3.9% | 0.38 | 4.5% | 0.24 | 2.8% | 0.43 | 5.2% | 0.68 | 8.3% |
| High Positive | 180 | 5.263 | 0.26 | 4.9% | 0.32 | 6.1% | 0.22 | 4.3% | 0.36 | 6.8% | 0.41 | 7.8% |
| Mod Positive | 180 | 2.535 | 0.15 | 5.7% | 0.17 | 6.8% | 0.11 | 4.2% | 0.21 | 8.3% | 0.25 | 10.0% |
| Mod Positive | 180 | 2.237 | 0.10 | 4.6% | 0.12 | 5.5% | 0.08 | 3.6% | 0.14 | 6.3% | 0.18 | 8.1% |
| Low Positive | 180 | 1.350 | 0.08 | 5.8% | 0.09 | 6.8% | 0.06 | 4.3% | 0.10 | 7.5% | 0.11 | 8.4% |
| Low Positive | 180 | 1.320 | 0.08 | 5.9% | 0.10 | 7.5% | 0.07 | 5.6% | 0.11 | 8.0% | 0.14 | 10.7% |
| Near Cut-off | 180 | 1.020 | 0.06 | 5.9% | 0.07 | 7.2% | 0.05 | 4.9% | 0.09 | 9.0% | 0.11 | 10.4% |
| Near Cut-off | 180 | 0.969 | 0.06 | 6.5% | 0.08 | 7.9% | 0.05 | 5.2% | 0.08 | 8.8% | 0.10 | 10.1% |
| High Negative | 180 | 0.668 | 0.05 | 7.0% | 0.05 | 8.2% | 0.03 | 4.9% | 0.06 | 9.3% | 0.07 | 10.3% |
| High Negative | 180 | 0.653 | 0.05 | 8.4% | 0.06 | 9.7% | 0.04 | 5.8% | 0.07 | 11.1% | 0.08 | 12.1% |
| Negative | 180 | 0.352 | 0.03 | 9.3% | 0.04 | 11.3% | 0.03 | 7.5% | 0.05 | 14.0% | 0.05 | 15.5% |
| Negative | 180 | 0.320 | 0.03 | 10.5% | 0.04 | 12.4% | 0.02 | 6.8% | 0.05 | 15.0% | 0.05 | 16.4% |
| Non-Reactive Control | 180 | 0.245 | 0.03 | 12.6% | 0.04 | 14.8% | 0.02 | 7.4% | 0.04 | 17.3% | 0.05 | 18.7% |
| Reactive Control | 180 | 8.869 | 0.51 | 6.0% | 0.59 | 6.8% | 0.34 | 3.9% | 0.73 | 8.3% | 0.87 | 9.9% |
b. Linearity/assay reportable range: N/A
c. Traceability, Stability, Expected values (controls, calibrators, or methods): There is no standard available for measuring HSV antibody in serum
d. Detection limit: Not applicable. This device is for qualitative HSV-2 antibody detection.
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# e. Analytical specificity:
Cross Reactivity: A study was conducted to assess cross reactivity with the ZEUS ELISA HSV gG-2 IgG test system using sero-positive serum to EBV VCA IgG, ANA, Rubella, VZV IgG, CMV, Measles, Treponema pallidum, Gonorrhea, HPV, Chlamydia, rheumatoid factor (RF), Toxoplasma gondii, and HSV-1 IgG. To demonstrate the assay only detects HSV-2 IgG antibody, HSV-2 IgM and IgG sero-positive samples were characterized by FDA cleared HSV-2 IgM ELISA test system from which total IgG was removed. Micro-particle and ELISA immunoassay test systems manufactured by various companies for commercial distribution were used to determine the sero-positivity of the samples. Ten samples for each possible cross-reactant were tested. In total, 140 samples were tested for possible cross reactivity with 14 analytes. None of the samples showed cross-reactivity with any of the analytes tested. The results of this study are summarized in Table 3.
Table 3. Cross Reactivity Summary
| HSV gG-2 Cross reactivity Study | |
| --- | --- |
| Analyte | positive/tested |
| EBV VCA IgG | 0/10 |
| ANA | 0/10 |
| Measles | 0/10 |
| Rubella | 0/10 |
| CMV | 0/10 |
| VZV | 0/10 |
| T. pallidum | 0/10 |
| Gonorrhea | 0/10 |
| HPV | 0/10 |
| Chlamydia | 0/10 |
| RF | 0/10 |
| T. gondii | 0/10 |
| HSV gG-1 | 0/10 |
| HSV-2 IgM | 0/10 |
Specimens known to contain potentially cross reactive antibodies to Candida albicans have not been tested with this device, therefore it is unknown if there is any cross reactivity with these antibodies. This is indicated in the limitation section of the package insert.
Interfering Substances: The effect of potentially interfering substances on sample results generated using the ZEUS ELISA HSV gG-2 IgG test system was evaluated with the following possible interfering substances: albumin, bilirubin, cholesterol, hemoglobin, triglycerides and intralipids.
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The level of each potentially interfering substance is as follows:
Bilirubin: 1mg/dL (low), 15 mg/dL (high)
Albumin: 3.5 g/dL (low), 5 g/dL (high)
Cholesterol: 150 mg/dL (low), 250 mg/dL (high)
Triglycerides: 150 mg/dL (low), 500 mg/dL (high)
Hemoglobin: 10 g/dL (low), 20 g/dL (high)
Intralipid: 300 mg/dL (low), 750 mg/dL (high)
Three samples for HSV gG-2 were chosen based on their performance on the investigational device: positive, borderline and negative. The possible interfering substances were added to the samples. Test and control samples were evaluated in replicates of ten. All positive samples showed a change of signal less than 20%. All borderline samples showed a change of signal less than 20% with the exception of the high spike of intralipid (75.5%). The negative sample showed a change of signal (>20%) with the low spike (42.9%) and high spike of albumin (78.6%), the high spike of hemoglobin (245.2), the low spike of intralipid (78.6%), and the low and high spikes of bilirubin (272.7% and 318.2%, respectively). The negative sample results in each instance stayed below the cut-off and the change in signal did not affect the qualitative result.
f. Assay cut-off:
The cut off for this assay was established against a panel of 25 confirmed negative specimens as well as nine clinically characterized positive samples. The mean and standard deviation were established for the negative population. Using a mathematical calculation based on these data, a theoretical cut-off was established and validated with the characterized specimens. Based upon the results of this testing, the manufacturer established the following guidelines for interpretation of patient samples.
Interpretations:
Index Values or OD ratios are interpreted as follows:
| Result | Index Value or OD Ratio |
| --- | --- |
| Negative | ≤ 0.90 |
| Equivocal | 0.91 to 1.09 |
| Positive | ≥ 1.10 |
1. An OD ratio ≤ 0.90 indicates no detectable IgG antibody to HSV-2.
2. Specimens with OD ratio values in the equivocal range (0.91 – 1.09) should be retested in duplicate. If on retesting one of the two samples remains equivocal, the samples should be tested by an alternate serological procedure
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such as Westen Blot or re-evaluated by drawing another sample one to three weeks later.
3. An OD ratio $\geq 1.10$ indicates that HSV-2 IgG antibodies were detected.
4. The numeric value of the final result above the cutoff is not indicative of the amount of anti-HSV-2 IgG antibody present.
5. Test results should be interpreted in conjunction with the clinical history, epidemiological data and other information available to the attending physician in evaluating the patient.
6. False positive test results may occur. Repeat testing or testing with a different device may be indicated in some settings e.g., patients with low likelihood of HSV infection.
## 2. Comparison studies:
a. Method comparison with predicate device: Comparative studies were performed using a total of 788 samples at three clinical sites to demonstrate the equivalence of the ZEUS ELISA HSV gG-2 test system to the reference method (a commercially distributed HSV-1 and 2 immunoblot test system). Five hundred and eighty-eight samples were from the Intended Use populations of sexually active individuals (n=336) and pregnant women (n=252) with an HSV test requested. One hundred additional samples from a low prevalence population of 17-19 year old individuals (n=100) were tested as well as 100 HSV samples acquired from the CDC (CDC panel). The clinical sites and quantity of samples tested are summarized in Table 4.
| Populations | Number of Samples Tested at Each Site | | | |
| --- | --- | --- | --- | --- |
| | Site 1 | Site 2 | Site 3 | Total |
| Sexually Active Individuals | 100 | 136 | 100 | 336 |
| Pregnant women | 33 | 155 | 64 | 252 |
| Low Prevalence Population | 33 | 33 | 34 | 100 |
| CDC Panel | 33 | 25 | 42 | 100 |
Results of this comparative study in the three sites combined are presented below. The data was analyzed counting any discordant equivocal results between the comparator and the investigational device against the performance of the investigational device.
## Performance in the Intended Use Population of Sexually Active Individuals: A total of 336 prospective, unselected samples from sexually active individuals with an HSV-2 test ordered were tested with the ZEUS ELISA HSV gG-2 IgG Test System and compared with a commercially available immunoblot test. The samples were submitted for HSV-2 antibody
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testing, sequentially numbered, de-identified and archived. Results are presented in Table 5.
| | Table 5. Sexually Active Individuals | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Immunoblot | | | | | | |
| | | Positive | Equivocal | Negative | Site Total | | % Agreement* | 95% CI |
| ZEUS ELISA | | | | | | | | |
| | Positive Equivocal Negative Site Total | 70 | 0 | 1 | 71 | PPA | 93.3% (70/75) | 86.9%-98.5% |
| | | 0 | 0 | 0 | 0 | | | |
| | | 1 | 4 | 260 | 265 | NPA | 99.6% (260/261) | 97.9%-100% |
| | | 71 | 4 | 261 | 336 | | | |
*Equivocal results in one test but not the other were treated as discrepant and included in the calculations.
Performance in the Intended Use Population of Pregnant Women: A total of 252 prospective, unselected samples from pregnant women with an HSV-2 test ordered were tested with the ZEUS ELISA HSV gG-2 IgG Test System and compared with a commercially available immunoblot test. One hundred and twenty-one samples were from women in the first trimester, 64 from women in the second trimester and 67 from women in the third trimester. The samples were submitted for HSV-2 antibody testing, sequentially numbered, de-identified and archived. Results are presented in Table 6.
| | Table 6. Pregnant Women | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Immunoblot | | | | | | |
| | | Positive | Equivocal | Negative | Site Total | | % Agreement* | 95% CI |
| ZEUS ELISA HSV gG-2 | | | | | | | | |
| | Positive Equivocal Negative Site Total | 70 | 1 | 1 | 72 | PPA | 98.6% (70/71) | 92.5%-100% |
| | | 0 | 0 | 0 | 0 | | | |
| | | 1 | 0 | 179 | 180 | NPA | 98.9% (179/181) | 96.1%-99.9% |
| | | 71 | 1 | 180 | 252 | | | |
* Equivocal re*Equivocal results in one test but not the other were treated as discrepant and included in the calculations.
Performance in a Low Prevalence Population: A total of 100 samples requested to be collected from 17-19 year old individuals in a non-STD setting were tested and compared with a commercially available immunoblot test. These samples were purchased from a New York vendor. The results are shown in Table 7.
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| | Table 7. Low Prevalence Population | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | Immunoblot | | | | | | |
| | | Positive | Equivocal | Negative | Site Total | | % Agreement* | 95% CI |
| ZEUS ELISA HSV gG-2 | | | | | | | | |
| | Positive | 0 | 0 | 0 | 0 | PPA | N/A | N/A |
| | Equivocal | 0 | 0 | 2 | 2 | | | |
| | Negative | 0 | 0 | 98 | 98 | NPA | 98.0% (98/100) | 93.0%-99.8% |
| | Site Total | 0 | 0 | 100 | 100 | | | |
*Equivocal results in one test but not the other were treated as discrepant and included in the NPA calculations.
CDC HSV-2 IgG Panel: A total of 100 samples were obtained from the CDC for analysis. The performance of the ZEUS ELISA HSV gG-2 IgG Test System was assessed using a masked, well characterized HSV serum panel from the CDC. The panel consists of 46 HSV-2 IgG positive and 54 HSV-2 IgG negative samples. Of the 46 HSV-2 IgG positive samples, 24 samples were HSV-1 IgG and HSV-2 IgG dual-positive samples. The results are presented to convey further information on the performance of the test kit and do not imply endorsement of the assay by the CDC.
| | Table 8. CDC HSV Panel | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | CDC HSV-2 Results | | | | | | |
| | | Positive | Equivocal | Negative | Site Total | | % Agreement* | 95% CI |
| ZEUS ELISA HSV gG-2 | | | | | | | | |
| | Positive | 46 | 0 | 0 | 46 | PPA | 100.0% (46/46) | 93.7%-100% |
| | Equivocal | 0 | 0 | 0 | 0 | | | |
| | Negative | 0 | 0 | 54 | 54 | NPA | 96.9% (54/54) | 94.6%-100% |
| | Site Total | 46 | 1 | 54 | 100 | | | |
*Equivocal results in one test but not the other were treated as discrepant and included in the NPA calculations.
b. Matrix Comparison: N/A
3. Clinical studies:
a. Clinical Sensitivity: N/A
b. Clinical specificity: N/A
c. Other clinical supportive data (when a. and b. are not applicable):
4. Clinical cut-off: N/A
5. Expected values/Reference range:
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The observed prevalence with the Intended Use populations was assessed internally and externally at two sites with unselected, masked and archived sera. With the sexually active individuals $(n = 336)$ the observed prevalence with the ZEUS ELISA HSV gG-2 was $21.4\%$ (72/336).
In the population of pregnant women $(n = 252)$ , the observed prevalence with the ZEUS ELISA HSV gG-2 was $28.7\%$ (72/251). One sample was excluded from this analysis due to unknown age.
Values for the prevalence observed with the investigational device in each age group for the two populations are summarized in tables 9 and 10.
Table 9. Observed Prevalence with Sexually Active Individuals
| Age | Sex | HSV gG-2 | | total | Observed % Prevalence HSV gG-2 |
| --- | --- | --- | --- | --- | --- |
| | | Positive | Negative | | |
| 15-19 | Male | 1 | 10 | 11 | 9.1% |
| | Female | 2 | 23 | 25 | 8.0% |
| 20-29 | Male | 2 | 31 | 34 | 5.9% |
| | Female | 19 | 69 | 88 | 21.6% |
| 30-39 | Male | 2 | 18 | 20 | 10.0% |
| | Female | 17 | 43 | 60 | 28.3% |
| 40-49 | Male | 7 | 22 | 29 | 24.1% |
| | Female | 5 | 16 | 21 | 23.8% |
| 50-59 | Male | 7 | 20 | 27 | 25.9% |
| | Female | 5 | 5 | 10 | 50.0% |
| 60-69 | Male | 3 | 6 | 9 | 33.3% |
| | Female | 1 | | 1 | 100% |
| 70 + | Male | | 1 | 1 | 0.0% |
| | Female | | | 0 | 0.0% |
| Sub-total | Male | 23 | 108 | 131 | 17.6% |
| | Female | 49 | 156 | 205 | 23.9% |
| | Total | 71 | 264 | 336 | 21.1% |
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Table 10. Observed Prevalence with Pregnant women
| | HSV gG-2 | | | Observed % Prevalence |
| --- | --- | --- | --- | --- |
| Age | Positive | Negative | total | HSV gG-2 |
| 15-19 | 2 | 22 | 24 | 8.3% |
| | | | | |
| 20-29 | 46 | 103 | 149 | 30.9% |
| | | | | |
| 30-39 | 15 | 48 | 63 | 23.8% |
| | | | | |
| 40-49 | 9 | 6 | 15 | 60.0% |
| | | | | |
| Total | 72 | 179 | 251* | 28.7% |
*one negative sample submitted with age unknown was excluded
The hypothetical predictive values for the two populations are shown in the table below. The calculations are based on the ZEUS ELISA HSV gG-2 IgG having:
1. A positive percent agreement of 93.3% and a negative percent agreement of 99.6% in sexually active adults
2. A positive percent agreement of 98.6% and a negative percent agreement of 98.9% in pregnant women
Table 11. Prevalence vs. Hypothetical Predictive Values
| Prevalence | HSV gG-2 IgG | | | |
| --- | --- | --- | --- | --- |
| | Sexually Active Individuals | | Pregnant Women | |
| | PPV | NPV | PPV | NPV |
| 50% | 99.6% | 93.7% | 98.9% | 98.6% |
| 40% | 99.4% | 95.7% | 98.4% | 99.1% |
| 30% | 99.1% | 97.2% | 97.5% | 99.4% |
| 25% | 98.8% | 97.8% | 96.8% | 99.5% |
| 20% | 98.4% | 98.3% | 95.7% | 99.6% |
| 15% | 97.8% | 98.8% | 94.1% | 99.8% |
| 10% | 96.5% | 99.3% | 90.9% | 99.8% |
| 5% | 92.9% | 100.0% | 82.5% | 100.0% |
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.