A branched, synthetic oligopeptide corresponding to a region of glycoprotein G of HSV-1 reacts sensitively and specifically with HSV-1 antibodies in an ELISA

Evaluation of a cystatin-like protein of Trichinella spiralis for serodiagnosis and identification of immunodominant epitopes using monoclonal antibodies

An antigenic cystatin-like protein (Ts-CLP) selected from cDNA library of intestinal infective larvae at 6 h post-infection, was expressed by prokaryotes in the form of a histidine-tagged protein (rTs-CLP). The fusion protein was purified by an on-column refolding procedure using Ni-NTA affinity chromatography. An indirect rTs-CLP ELISA was developed using 270 known negative serum samples from commercial swine maintained under non-special pathogen free conditions. Based on the distribution of the signal-to-positive (S/P) ratio, a cut-off value was set at 0.30. Using this cut-off value, rTs-CLP ELISA was evaluated using sera from swine experimentally infected with 1000 and 50,000 muscle larvae of Trichinella spiralis. Specific IgG antibodies were detectable by rTs-CLP ELISA as soon as 17 days post-infection (dpi), but the commercial ELISA kit based on excretory-secretory (ES) antigens did not permit detection before 21 dpi. Three monoclonal antibodies (McAbs) against Ts-CLP (designated 1H9, 6B5 and 7F8) were obtained by screening with both rTs-CLP ELISA and ES ELISA methods. Two dominant epitopes recognized by McAbs were determined by analysis with overlapping fusion peptides and synthetic peptides. One epitope ³⁹ HEALFSSDLKQESGV ⁵³ was recognized by 1H9 and 6B5, and the other epitope ¹⁷⁸ REALFSSDSKEQSGV ¹⁹² was recognized by 7F8. The generation of McAbs against Ts-CLP and the characterization of the two dominant epitopes provide a foundation for the development of a specific early serodiagnostic strategy for T. spiralis infection.

Application and expression of HSV gG1 protein from a recombinant strain

According to the homologous sequence of glycoprotein G1 (gG1) genes from different strains of herpes simplex virus type 1 (HSV-1), a pair of primers was designed to amplify the gG1 gene fragment by PCR. Both the PCR product and the pGEX-4T-1 vector were digested with EcoR I and Sal I. The gG1 gene fragment was subcloned into the digested pGEX-4T-1 vector to construct a recombinant plasmid (pGEX-4T-1-gG1). The resultant plasmid was identified by dual-enzyme digestion and sequence analysis, and then transformed into Escherichia coli BL21 for expression under the induction of isopropyl β-D-1-thiogalactoside (IPTG). The expressed GST-gG1 fragment was detected by SDS-PAGE and purified by affinity chromatography. The properties of GST-gG1 fragment were evaluated by immunoblot analysis. Enzyme-linked immunosorbent assays (ELISAs) based on the GST-gG1 fragment were used for determining IgG or IgM to HSV-1. The GST-gG1 fragment-specific ELISA was also compared with ELISA with whole-HSV-1 antigen and commercial ELISA kits. The gG1-specific IgG and IFN-γ producing CD8+ T cells were induced in mice immunized with the GST-gG1 fragment. These results indicated that the GST-gG1 fragment could be used for replacing whole-virus antigen to detect IgM and IgG to HSV-1 in human sera, which provided a strategy for developing vaccines to protect HSV-1 infection using gG1 fragment.

Herpes simplex virus type-2 in Egyptian patients with bladder cancer or cystitis

The present study was designed to investigate the prevalence of herpes simplex virus type-2 (HSV-2) in Egyptian patients with bladder cancer or cystitis and to evaluate the performance of different diagnostic HSV-2 assays. The study included 50 patients: 27 with bladder cancer (group I), 23 with cystitis (group II) and 20 subjects as controls (group III). HSV-2 DNA was detected using polymerase chain reaction (PCR) on bladder tissue and buffy coat cells (BCC). Electron microscopic studies (EMS) on BCC and ELISAs for IgM, IgG and specific glycoprotein G-2 (gG-2) IgG were performed. HSV-2 DNA was detected by PCR on bladder tissue biopsies in 29.6% and 21.7% of group I and II respectively and it was also detected by PCR on BCC in 22.2% and 21.7% of group I and II respectively. EMS revealed HSV like particles in 16.6% of cases. IgG, specific gG-2 IgG and IgM were detected in 30%, 16% and 6% of cases respectively. The different assays were evaluated in relation to PCR on bladder tissue biopsies. The gG-2-based ELISA and EMS on BCC were found to be highly specific (97.3% and 100% respectively), with similar low sensitivity of approximately 54%. PCR on BCC was the most sensitive assay. The association of HSV-2 with bladder cancer is suggested especially in schistosomal patients.

HIV-1, HSV-2 and syphilis among pregnant women in a rural area of Tanzania: prevalence and risk factors

BACKGROUND

Evidence suggests that a substantial proportion of new HIV infections in African countries are associated with herpes simplex virus type 2 (HSV-2). Thus, the magnitude of HSV-2 infection in an area may suggest the expected course of the HIV epidemic. We determined prevalence of genital herpes, syphilis and associated factors among pregnant women from a remote rural Tanzanian community that has a low but increasing HIV prevalence.

METHODS

We analysed 1296 sera and responses to a standard structured questionnaire collected from pregnant women aged between 15-49 years, attending six different antenatal clinics within rural Manyara and Singida regions in Tanzania. Linked anonymous testing (with informed consent) of the serum for specific antibodies against HSV-2 was done using a non-commercial peptide- 55 ELISA. Antibodies against syphilis were screened by using rapid plasma reagin (RPR) and reactive samples confirmed by Treponema pallidum haemagglutination assay (TPHA).

RESULTS

Previous analysis of the collected sera had shown the prevalence of HIV antibodies to be 2%. In the present study the prevalence of genital herpes and syphilis was 20.7% (95% CI: 18.53-23.00) and 1.6% (95% CI: 1.03-2.51), respectively. The presence of HSV-2 antibodies was associated with polygamy (OR 2.2, 95% CI: 1.62 - 3.01) and the use of contraceptives other than condoms (OR 1.7, 95% CI: 1.21 - 2.41). Syphilis was associated with reporting more than one lifetime sexual partner (OR 5.4, 95% CI: 1.88 - 15.76) and previous spontaneous abortion (OR 4.3, 95% CI: 1.52-12.02).

CONCLUSION

The low prevalence of HIV infection offers a unique opportunity for strengthening HIV prevention in a cost-effective manner. The identification and control of other prevalent curable STIs other than syphilis and specific intervention of HSV-2 in specific populations like pregnant women would be one among approaches towards preventing incident HIV infections.

Detection of HSV type-1 and type-2 IgG using an in vitro PCA based homogeneous immunoassay

Enzyme immunoassays (EIAs) are widely used in the clinical laboratory and research institutes for the detection of biologically relevant analytes. Almost all EIAs are heterogeneous in nature and require multiple steps of process. In contrast, homogeneous immunoassays (HA) offer a simplified one-step approach with a number of potential advantages over contemporary heterogeneous EIAs such as higher throughput and greater clinical utility. Utilizing TEM-1 beta-lactamase as a reporter enzyme, we have developed HAs based on in vitro protein fragment complementation (PCA) for the detection of antibodies and potentially be used for antigens or other biomarkers. In this proof-of-principle study we demonstrate the successful in vitro differentiation of anti-herpes simplex virus (HSV) type-1 and type-2 Immunoglobulin G (IgG) in human serum with high sensitivity and specificity.

Chimeric multiple antigenic peptides for simultaneous detection of specific antibodies to HIV-1 groups M, N, O, and HIV-2

Synthetic peptides have frequently replaced the more costly recombinant proteins or viral lysates as the antigens of choice for detection of antibodies to human immunodeficiency viruses. However, development of an assay that is sensitive to all the types and groups of HIV, including the divergent strains of HIV-1 group O, group N, and HIV-2, would require many peptides derived from different types and groups of HIV. Combining multiple peptide antigens may reduce the analytical sensitivity of the individual peptide due to the competition for binding to the solid surface when used in an enzyme immunoassay format. In this study, we developed and evaluated two chimeric multiple antigenic peptides (CMAP) for simultaneous detection of specific antibodies to HIV-1 groups M, N, O, and HIV-2. Both CMAPs correctly identified 304 known HIV positive serum or plasma specimens (260 HIV-1 group M of varying subtypes, 3 group O, and 41 HIV-2) and one chimpanzee serum specimen (group N) and all 66 known HIV negative specimens. CMAP performance was superior to the corresponding individual linear peptides or a linear peptide mixture. The results indicate that CMAPs are useful for the development of highly sensitive and specific assays for the detection of infections caused by HIV-1, including group M, N, and O, and HIV-2.

Prevalence of antibodies against herpes simplex virus types 1 and 2 in children and young people in an urban region in Tanzania

Herpes simplex virus type 1 (HSV-1) is transmitted by close contact, both sexual and nonsexual, and infections are acquired during childhood and adolescence. Herpes simplex virus type 2 (HSV-2), however, is thought to be transmitted mainly by sexual contact. Most HSV-2 infections are consequently expected to occur after the onset of sexual activity. Recent reports indicate an increasing prevalence of HSV-2 on the African continent, but most studies have been performed on adult cohorts. In the present study, we collected sera from Tanzanian children and young persons from 1 to 20 years old, with at least 100 individuals in each age group. Antibodies against HSV-1 and HSV-2 were detected by an in-house Western blot method which was shown to perform well in comparison with a commercial Western blot assay. Type-specific antibodies were also analyzed by two noncommercial enzyme-linked immunosorbent assay methods based upon the antigenicities of branched synthetic oligopeptides corresponding to epitopes in glycoprotein G of HSV-1 or HSV-2. The prevalence of HSV-1 antibodies increased gradually from 73% for the age group of 1 to 4 years to 92% for the age group of 17 to 20 years. The prevalence of HSV-2 antibodies was unexpectedly high, as 15% of the children were infected by the age of 8 years, with the incidence increasing gradually to 40% in the age group of 17 to 20 years. The reason for this unexpectedly high frequency is not clear but could suggest that nonsexual transmission of HSV-2 is more common than previously thought. There was no statistically significant association between seropositivities for HSV-2 and human immunodeficiency virus.