Analysis of the HSV-2 early AG-4 antigen

Herpes simplex virus 2 (HSV-2) infected cell proteins are among the most dominant antigens of a live-attenuated HSV-2 vaccine

Virion glycoproteins such as glycoprotein D (gD) are believed to be the dominant antigens of herpes simplex virus 2 (HSV-2). We have observed that mice immunized with a live HSV-2 ICP0^- mutant virus, HSV-2 0ΔNLS, are 10 to 100 times better protected against genital herpes than mice immunized with a HSV-2 gD subunit vaccine (PLoS ONE 6:e17748). In light of these results, we sought to determine which viral proteins were the dominant antibody-generators (antigens) of the live HSV-2 0ΔNLS vaccine. Western blot analyses indicated the live HSV-2 0ΔNLS vaccine elicited an IgG antibody response against 9 or more viral proteins. Many antibodies were directed against infected-cell proteins of >100 kDa in size, and only 10 ± 5% of antibodies were directed against gD. Immunoprecipitation (IP) of total HSV-2 antigen with 0ΔNLS antiserum pulled down 19 viral proteins. Mass spectrometry suggested 44% of immunoprecipitated viral peptides were derived from two HSV-2 infected cells proteins, RR-1 and ICP8, whereas only 14% of immunoprecipitated peptides were derived from HSV-2’s thirteen glycoproteins. Collectively, the results suggest the immune response to the live HSV-2 0ΔNLS vaccine includes antibodies specific for infected cell proteins, capsid proteins, tegument proteins, and glycoproteins. This increased breadth of antibody-generating proteins may contribute to the live HSV-2 vaccine’s capacity to elicit superior protection against genital herpes relative to a gD subunit vaccine.

The diagnosis of recent herpes simplex virus type 2 genital infections by the simplex-2 test

The prevalence of complement-fixing (CF) antibody against the AG-4 early antigen of herpes simplex virus (HSV) type 2 (HSV-2) was determined in patients with culture confirmed HSV-2 genital herpes and control groups using a commercial HSV-2 early antigen (Simplex-2; Gene Link Australia Ltd). Eighty seven per cent of 39 sera collected between 14 and 28 days after confirmed primary and recurrent HSV-2 infection were positive. In acute sera collected between 2-10 days after onset the Simplex-2 test was negative in all 90 patients with presumed primary infection but positive in 53% of 230 sera from recurrent infection. A specificity of 90-94.5% was obtained by testing 36 patients with recent proven HSV-1 infection and 331 control group patients. The Simplex-2 test may be useful in some cases of culture-negative, clinically suspected genital HSV-2 lesions only when sera are collected between 14-28 days after primary and recurrent infection. Its lack of specificity makes it unsuitable for the routine diagnosis of recent HSV-2 infection in the general population.

Lack of serum antibodies to the major HSV-2 specified DNA-binding protein before diagnosis of cervical neoplasia

We report results based on a prospective case-control study within a cohort obtained by linking the Finnish Social Insurance Institutions Mobile Clinic Survey Registry and the Finnish Cancer Registry. The overall prevalence of herpes virus early antigen (ICSP 11/12) antibodies was similar in controls and in cervical neoplasia cases (consisting of invasive cervical carcinoma, ICC, and cervical intraepithelial neoplasia group III, CIN III cases). However, those CIN III cases, who after a long lag period (average 7 years after the blood sample was drawn) developed cervical neoplasia, had significantly lower antibody levels than did matched controls. Their ICSP 11/12 antibody levels became higher the shorter the lag period. The negative correlation between the ICSP 11/12 antibody levels and the lag period was most pronounced in the HSV-2 seropositive CIN III cases. In an analysis of cross-sectional case-control material from the Clinic of Obstetrics and Gynaecology, Tampere University Central Hospital, the patients with ICC had the highest ICSP 11/12 antibody levels. Statistically significant differences between cases and controls were not found. We conclude that in cervical neoplasia the kinetics of ICSP 11/12 antibody levels are determined by the malignant process itself. The cervical disease may selectively induce early viral antigens, thus giving rise to the antibody response described in this paper.

Type specificity of complement-fixing antibody against herpes simplex virus type 2 AG-4 early antigen in patients with asymptomatic infection

We evaluated the type specificity of complement-fixing (CF) antibody against the AG-4 early antigen of herpes simplex virus (HSV) type 2 (HSV-2) by comparing a commercial AG-4 CF kit (Simplex-2; Gene Link Australia, Inc., Princeton, N.J.) with quantal microneutralization (MN) and absorption-Western blotting in testing sera from patients with and without a history of genital herpes. Sera characterized as HSV type 1 (HSV-1) or HSV-2 positive or negative by MN were selected and tested by CF, and those with discordant results were further analyzed for specific antibodies by absorption with HSV-1 or HSV-2 antigen and Western blotting with heterologous HSV proteins. A total of 34 of 42 (81%) sera HSV-2 positive by MN, 19 of 43 (44%) sera HSV-1 positive by MN, and 0 of 19 sera negative by MN were positive by CF. Absorption-Western blotting showed that 12 of 18 (67%) sera HSV-1 positive by MN but positive by CF had no HSV-2-specific antibody and that all 7 sera HSV-2 positive by MN but negative by CF had HSV-2-specific antibody. When MN and absorption-Western blotting data were combined to analyze patients with no history of genital herpes, 7 of 19 (37%) with no HSV-2-specific antibody were positive by CF, and 7 of 27 (26%) with HSV-2-specific antibody were negative by CF. The positive and negative predictive values for the CF test were 78 and 75%, respectively, in this group. The presence of antibody to the HSV AG-4 antigen does not discriminate sufficiently between HSV-1- and HSV-2-infected patients to be of value in predicting HSV-2 infection in the absence of symptomatic disease.

Expression of the herpes simplex virus type-2 major DNA-binding protein (ICP8) gene in COS-1 cells

By the use of an SV40 origin of replication plasmid vector and the COS-1 cell system, expression of the gene encoding the herpes simplex virus type-2 (HSV-2) major DNA binding protein (ICP8) has been achieved. The HSV-2 4.5 kb BglII 0 DNA fragment containing the ICP8 coding region was inserted into the plasmid vector pSVOd containing the SV40 origin of replication. Transfection of COS-1 cells by the resultant recombinant plasmid (pSVOd20), and subsequent multiplication of this plasmid, led to the production of the HSV-2 major DNA binding protein in sufficient quantities to allow its detection with either monoclonal or polyclonal antibodies as well as sera taken from HSV-2 patients.