| Abstract|| |
Introduction: Type-specific serology (TSS) test for herpes simplex virus (HSV) have been used as a research tool in seroepidemiological studies for some years. However, TSS as a diagnostic modality for diagnosis of current episode of genital herpes is not well documented. Aims and Objectives: To measure the seroprevalence of type-specific HSV Type 1 (HSV-1) and Type 2 (HSV-2) IgG antibodies in cases provisionally diagnosed as primary and recurrent genital herpes and to evaluate the role of TSS as a diagnostic modality for diagnosis of genital herpes versus polymerase chain reaction (PCR). Materials and Methods: A cross-sectional study was performed over a period of 10 months in which 44 adult patients with clinically suspected genital herpes were recruited. An in-house glycoprotein G gene base PCR was performed directly from the genital lesion specimen for simultaneous detection and typing of HSV. TSS was performed to detect IgG antibody against HSV-1 and 2 in all patients using commercially available kits, and the results were compared. Results: Seroprevalence of HSV-1 IgG was 43% among primary and 65% among recurrent genital herpes cases (P = 0.22). Whereas that of HSV-2 IgG was found to be 14% and 83% in respective patient group (P = 0.0001). When compared to PCR results HSV-1 IgG detection in both primary and recurrent genital herpes diagnosis had poor specificity, positive predictive value, and sensitivity. Whereas, HSV-2 serology had a sensitivity of 13.33% and 73.33% in primary and recurrent genital herpes and specificity of 83.33% and 85.71%, respectively.
Conclusion: HSV-2 IgG detection helps in strengthening the diagnosis of recurrent HSV-2 disease, whereas the absence of HSV-2 IgG antibody helps in excluding genital herpes as a likely cause of recurrent genital ulceration. However, detection of HSV-1 IgG antibody may not be useful for diagnosis in patients of genital ulcer disease.
Keywords: Genital herpes, herpes simplex virus, type-specific serology
|How to cite this article:|
Patwardhan V, Bhalla P. Role of type-specific herpes simplex virus-1 and 2 serology as a diagnostic modality in patients with clinically suspected genital herpes: A comparative study in Indian population from a tertiary care hospital. Indian J Pathol Microbiol 2016;59:318-21
|How to cite this URL:|
Patwardhan V, Bhalla P. Role of type-specific herpes simplex virus-1 and 2 serology as a diagnostic modality in patients with clinically suspected genital herpes: A comparative study in Indian population from a tertiary care hospital. Indian J Pathol Microbiol [serial online] 2016 [cited 2019 Jun 24];59:318-21. Available from: http://www.ijpmonline.org/text.asp?2016/59/3/318/188104
| Introduction|| |
Genital herpes simplex virus (HSV) infection is the second most prevalent sexually transmitted infection (STI) worldwide and the most common cause of genital ulcer disease (GUD) in the developed world. As a result of the wide variation in manifestations of genital herpes, a diagnosis based on pure clinical grounds has been shown to have a poor sensitivity; hence, laboratory tests for confirmation need to be employed. Genital herpes may be caused by either HSV Type 1 (HSV-1) or Type 2 (HSV-2) but, globally, the large majority of cases are caused by HSV-2. Laboratory methods for diagnosing genital herpes include direct microscopy, antigen detection, viral culture, polymerase chain reaction (PCR), and conventional and type-specific serology (TSS). PCR has, by far, shown greater sensitivity and can become the test of choice for symptomatic cases.
TSS for HSVs has been used as research tools in sero-epidemiological studies for some years., The rationale for serological testing is to identify asymptomatic HSV infection. Until now, HSV serology was unhelpful because it could not accurately differentiate antibodies to HSV-2 (almost exclusively as a result of genital herpes) from HSV-1 (predominantly generated in response to an oro-labial infection). HSV TSS uses commercially available tests that have the ability to accurately differentiate or “type” antibody responses generated by HSV-1 from HSV-2 infection. TSS as a diagnostic modality is not well documented for the diagnosis of genital herpes. However, HSV-2 TSS is indicated for patients with genital lesions in whom other tests like antigen detection, culture or PCR fail to detect HSV. TSS is also considered useful; for patients who are asymptomatic but have a history suggestive of genital herpes. This study was undertaken to measure the seroprevalence of type-specific HSV-1 and 2 IgG antibodies in cases provisionally diagnosed as primary and recurrent genital herpes and to evaluate the role of TSS as a diagnostic modality for diagnosis of genital herpes versus PCR.
| Materials and Methods|| |
A cross-sectional study was conducted over a period of 10 months on 44 adult male and female patients with clinically suspected genital herpes presenting with primary or recurrent multiple, painful, genital vesicles, or shallow ulcers on genitalia. All the patients were recruited from Department of Dermatology and Sexually Transmitted Diseases of our institute after taking informed consent. Socio-demographic data, relevant medical history, clinical signs, and symptoms of all subjects were recorded. The sample was collected directly from the genital lesion with the help of Dacron swabs for PCR and blood sample was collected for TSS from each patient. Blood samples were centrifuged, serum was separated and stored at -20°C till further testing was done. TSS for HSV 1 and 2 was performed as per manufacturer's instruction using HerpeSelect 1 ELISA (enzyme-linked immunosorbent assay) (FOCUS Diagnostics, USA) for the qualitative detection of human IgG class antibodies to HSV 1 and HerpeSelect 2 ELISA IgG (FOCUS Diagnostics, USA) ELISA for the qualitative detection of human IgG class antibodies to HSV 2. An in-house PCR test was performed for simultaneous detection and typing of HSV-1 and 2 from genital ulcer specimens using primers for HSV glycoprotein-G.
Socio-demographics of the study population have been analyzed using descriptive statistical parameters. Fisher's exact test was used to evaluate statistical significance (two-tailed P < 0.05 was considered significant). Sensitivity, specificity, positive- and negative-predictive value were calculated and reported as percentages.
| Results|| |
Of 44 patients recruited, 39 (89%) were males and 5 (11%) were females. Age distribution of the patients is shown in [Table 1]. According to the provisional diagnosis, we divided patients into two groups; primary genital herpes and recurrent genital herpes with 21 (48%) and 23 (52%) patients, respectively. A total of 31 patients (70%) presented with ulcerative lesions, 9 (21%) had crusted erosion, whereas only 4 patients (9%) had vesicular genital lesions.
We have measured the seroprevalence of HSV-1 and 2 in both primary and recurrent genital herpes groups, and the results of the ELISA are mentioned in [Table 2]. Seroprevalence of HSV-1 IgG was 43% (9/21) among primary and 65% (15/23) among recurrent genital herpes cases (P = 0.22). Whereas that of HSV-2 IgG was found to be 14% (3/21) and 83% (19/23) in the respective patient group (P = 0.0001).
|Table 2: Herpes simplex virus-1 and herpes simplex virus-2 IgG enzyme-linked immunosorbent assay results in primary and recurrent genital herpes cases|
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We have compared the results of TSS and PCR [Table 3] and [Table 4]. In primary genital herpes cases, HSV-1 TSS when compared to PCR had a sensitivity of 28.57%, positive predictive value: 25%, specificity: 57.14% and negative predictive value: 61.54%. Whereas in recurrent genital herpes cases, the values were 80%, 26.67%, 38.89%, and 87.5%, respectively.
|Table 3: Comparison between polymerase chain reaction and enzyme-linked immunosorbent assay for herpes simplex virus-2|
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|Table 4: Comparison between polymerase chain reaction and enzyme-linked immunosorbent assay for herpes simplex virus-1|
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While HSV-2 TSS, when compared to PCR in primary genital herpes cases, had sensitivity - 13.33%, positive predictive value - 66.67%, specificity - 83.33%, and negative predictive value - 27.8%. Whereas in recurrent genital herpes cases, the values were 73.33%, 91.67%, 85.71%, and 60%, respectively.
| Discussion|| |
We conducted the study in Delhi and found that the mean age of suspected cases of genital herpes in our study was found to be 32.4 years (range 18–50 years) [Table 1]. This is comparable to another study on GUD from four different states of India. In this study, the predominant age group was between 36 and 45 years of age. A possible reason for the higher age of patients presenting to our clinic could be the higher proportion of patients with recurrent disease. A previously published study from India supports our finding in which authors have documented an overall increase in the proportion of individuals belonging to older age group >35 years attending STI clinic from 1994 to 2006.
Number of study subjects presenting with primary and recurrent genital herpes in this study were 48% and 52%, respectively. This is comparable to a study conducted in North India which has also documented that there were more cases of recurrent genital herpes presenting to the hospital than primary genital herpes (60% study subjects presented with recurrent genital herpes).
We assessed the seroprevalence of HSV-1 IgG by type-specific ELISA which was found to be 54.5% with no significant difference between primary and recurrent genital herpes patients (P = 0.22) [Table 2]. Comparable results have been found in a study conducted in Seattle, Washington in which HSV-1 prevalence was 55.8% by Western blot analysis. In a community-based study conducted in Africa a very high (>90%) prevalence of HSV-1 antibody was found. This suggests that HSV-1 prevalence varies in different geographical areas.
We also assessed the seroprevalence of HSV-2 IgG by type-specific ELISA, which was found to be 50% [Table 2]. Type-specific HSV-2 IgG antibody was present in 14% sera of primary and 83% sera of recurrent genital herpes patients, which is a significant difference (P < 0.001) as would be expected. Comparable seroprevalence of 52.6% for HSV-2 antibody has been reported in a study conducted in Africa. In a recent study published in 2007 HSV-2 seroprevalence was 38% from Chennai whereas it was 57.2% from Goa.,, Thus, we see that there is the geographical difference in the HSV-2 seroprevalence.
We evaluated the role of type-specific HSV-1 and 2 antibody detection by type specific IgG ELISA as a diagnostic modality in patients with clinically suspected genital herpes. We analyzed this by comparing the results of type specific IgG ELISA in primary and recurrent genital herpes with respective results of PCR [Table 3]. We found that the presence of HSV-2 IgG antibody in primary genital herpes cases had low sensitivity and negative predictive value; however, it had good specificity and moderate positive predictive value. As against these results, HSV-2 IgG presence in the diagnosis of recurrent genital herpes has got higher sensitivity, specificity, and very good positive predictive value. These results suggest that HSV-2 IgG detection by ELISA has got a role when the diagnosis of recurrent genital herpes is concerned. Our results show the importance of HSV-2 IgG detection in strengthening the diagnosis of recurrent HSV-2 disease while the absence of HSV-2 IgG antibody helps in excluding genital herpes as a likely cause of recurrent genital ulceration.
A previous study conducted for evaluating the diagnostic role of type-specific HSV serology as against antigen detection from clinical lesions also concluded that the test was most useful for investigating patients who had recurrent genital ulceration as a diagnosis was achieved in 79% of cases. In another study authors concluded that a positive HSV-2 result generally equates to a diagnosis of genital herpes. However, because the specificity of TSS is not 100%, false-positive results may occur.
HSV-1 IgG detection in our study in both primary and recurrent genital herpes diagnosis showed to have poor specificity, positive predictive value, and sensitivity [Table 4]. HSV-1 IgG antibody presence does not necessarily indicate the presence of genital herpes. This antibody can rise in serum even after oral and other infections and cannot be differentiated from that arising from genital herpes episode. This suggests the minimal utility of HSV-1 IgG detection as a diagnostic modality. Thus, identification of HSV-1 IgG antibody may not be useful for diagnosis in patients of GUD highlighting the need for typing HSV-1 strains from the genital lesion. Similarly, in previous studies on TSS diagnostic armamentarium authors concluded that positive HSV-1 serology may represent an orolabial infection and not genital herpes at all. Differentiation of these two possibilities is often impossible, making a positive HSV-1 result unhelpful.,
Thus, clinicians need to bear in mind that HSV serology confirms that the individual has been exposed to that virus in the past, but will not establish whether particular signs and symptoms are caused by herpes. Moreover, TSS can be considered as one of the tests offered to patients with undiagnosed genital ulceration or patients with a questionable history or in those who have subclinical infections. A positive HSV-2 result generally equates to a diagnosis of genital herpes, however because the specificity of TSS is not 100%, false-positive results may occur.
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Dr. Preena Bhalla
Department of Microbiology, Maulana Azad Medical College, New Delhi
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4]