Virological studies in genital herpes

Oral sex and the transmission of viral STIs

OBJECTIVE

To review the literature on the role of oral sex in the transmission of viral sexually transmitted infections (STIs).

METHOD

A Medline search was performed using the keywords oro-genital sex, and those specific to each infection. Further references from each article identified by Medline were also included, as were relevant references from "Current contents".

CONCLUSIONS

Oral sex is a common sexual practice among both heterosexual and homosexual couples. The evidence suggests that HIV transmission can take place through oro-genital sex from penis to mouth and vagina to mouth. Case reports describe apparent transmission from mouth to penis although this appears less likely. The risk of oro-genital transmission of HIV is substantially less than from vaginal and anal intercourse. Receptive oro-genital sex carries a small risk of human papillomavirus infection and possibly hepatitis C, while insertive oro-genital contact is an important risk factor for acquisition of HSV 1. Oro-anal transmission can occur with hepatitis A and B. The transmission of other viruses may occur but is unproved. The relative importance of oral sex as a route for the transmission of viruses is likely to increase as other, higher risk sexual practices are avoided for fear of acquiring HIV infection.

Incidence of herpes simplex virus type-1 and type-2 from patients with primary (first-attack) genital herpes in Sheffield

In a study to determine the herpes simplex virus (HSV) type isolated from patients with primary (first-attack) genital herpes and to identify any clinical or epidemiological features that might influence the reported incidence of any particular viral type, there was almost an equal incidence of HSV-1 and HSV-2 isolated from women (48% versus 52%). In the case of women, the initial clinical diagnosis was correct in 97% with HSV-1 and 95% with HSV-2 infection. Amongst men, HSV-2 was isolated more frequently than HSV-1 (71% versus 29%). However, the initial clinical diagnosis in men was correct in only 53% with HSV-1 and 83% with HSV-2 infection. These results suggest that in primary genital herpes the incidence of HSV-1 and HSV-2 is probably equal, while in men the reported incidence of HSV-1 may be affected by underdiagnosis giving a falsely high incidence of HSV-2 infection.

Incidence of herpes genitalis in Northern Ireland in 1973-83 and herpes simplex types 1 and 2 isolated in 1982-4

During 1973 - 83 there was a pronounced rise in the number of new cases of herpes genitalis in Northern Ireland. This study of 127 patients with herpes genitalis shows that 30% had herpes simplex virus type 1 (HSV 1) and 70% had herpes simplex virus type 2 (HSV 2) infections. Of 41 sexual contacts who attended, only seven had herpes genitalis (caused in each case by HSV 2); another patient had a history of genital lesions, and one other of oral lesions, but HSV was not isolated from either patient. None of the other sexual contacts had a history of oral or genital infection. Of 31 women with herpes genitalis who consented to undergoing cervical cytology, five had atypical changes (all had primary herpes genitalis). Of these, four were infected with HSV 1 and one with HSV 2.

Topical treatment of recurrent genital herpes infections with foscarnet

In a double-blind study 86 patients with a total of 129 episodes of recurrent genital herpes were treated topically with 0.3% foscarnet or placebo cream. All patients considered, healing time was significantly shortened in the foscarnet group as compared to the placebo group (p less than 0.01). Subgrouped by sex, the healing time among men treated with foscarnet was significantly shortened as compared to those treated with placebo (p less than 0.002), whereas no statistical significant difference was observed among women. Foscarnet treated men with subpreputial lesions had a shorter period of ulcers (1.7 days) than placebo (3.4 days) treated men (p less than 0.02). Overall, foscarnet treatment reduced the period of redness, swelling, blisters and ulcers. Foscarnet was well tolerated, only in 1/57 patients treated was a moderate local adverse reaction recorded.

Identification and typing of herpes simplex virus by enzyme immunoassay with monoclonal antibodies

A double-antibody enzyme immunoassay was developed for the identification and typing of herpes simplex virus (HSV) by employing a polyclonal rabbit capture antiserum together with type-common and type 2-specific monoclonal antibodies as detectors. The test successfully identified 45 type I isolates and 30 type 2 isolates as HSVs. Compared with immunofluorescent staining and restriction endonuclease analysis, enzyme immunoassay correctly typed 45 type 1 and 30 type 2 HSV isolates. Enzyme immunoassay was 100% sensitive for identification of HSV as compared with cell culture and 100% specific for typing as compared with immunofluorescence and restriction endonuclease analysis. Electron microscopy analysis suggested that approximately 10(6) virus particles were required for the identification and typing of HSV by enzyme immunoassay.

Efficiency of the use of pock size on the chorioallantoic membrane of fertile hen's eggs as a method of typing herpes simplex viruses

One hundred and eighteen herpes simplex virus isolates were typed in a diagnostic virology laboratory using their standard procedure by pock size on the chorioallantoic membranes (CAMs) of fertile hen's eggs. Forty-three were typed as type 1 and 75 as type 2. The isolates were then sent to a research laboratory in which they were typed blind, with or without subsequent passage in tissue culture, by neutralization with type-specific antisera. Discrepant results were found with only two isolates. The isolates were then typed by the more time-consuming but unambiguous method of restriction endonuclease analysis of their DNAs. Typing by this method confirmed the typing by neutralization and established that typing by pock size on CAMs was correct in about 98% of cases.

Typing of clinical herpes simplex virus isolates with mouse monoclonal antibodies to herpes simplex virus types 1 and 2: comparison with type-specific rabbit antisera and restriction endonuclease analysis of viral DNA

A total of 122 clinical isolates of herpes simplex virus (HSV) from 107 patients were typed by using an indirect immunoperoxidase technique with commercially available type-specific rabbit antisera, recently developed mouse monoclonal antibodies to HSV types 1 and 2, and restriction endonuclease analysis of viral DNA. With the commercially available type-specific rabbit antisera, 34% of clinical HSV isolates were of indeterminate type; 63% of them were typed as HSV type 1 and 37% as HSV type 2 by using monoclonal antibody and restriction enzyme typing systems. Typing by immunofluorescence assay with the monoclonal antibodies gave identical results to those obtained by restriction enzyme analysis. Simultaneous infection with both HSV types was demonstrated by monoclonal antibody typing in five isolates from three patients. These findings were subsequently confirmed by plaque purification and restriction endonuclease analysis of viral DNA. Monoclonal antibodies were as sensitive as restriction enzyme analysis for the typing of clinical HSV isolates. Because of their simplicity, they are more amenable to use in clinical laboratories than is restriction endonuclease analysis.

Incidence of herpes simplex virus types 1 and 2 isolated in patients with herpes genitalis in Sheffield

Thirty-one strains of herpesvirus (HSV), isolated from patients presenting with the clinical features of herpes genitalis, were typed by polypeptide analysis of virus proteins in sodium dodecyl sulphate polyacrylamide gels. Nineteen (61.3%) of the isolates were shown to be HSV type 1 and 12 (38.7%) HSV type 2. There was no obvious difference in the incidence of HSV-1 in primary or recurrent infections and no apparent correlation between the genital site of isolation and virus type. The high incidence of genital HSV-1 infection in this group of patients is probably due to the increased practice of oro-genital contact and has possible implications for the future development of drugs and vaccines in the control of genital herpes.

Risk of recurrence after first episodes of genital herpes. Relation to HSV type and antibody response

To define risk factors associated with recurrent genital herpes-simplex-virus infection caused by either Type 1 or 2 herpesvirus (HSV-1 or HSV-2), we prospectively studied 137 patients with a first symptomatic episode of the disease and 87 with a recurrent episode. First episodes were divided into 78 primary infections (no antibodies to HSV in acute-phase serum) and 59 nonprimary infections (antibodies present). HSV-1 infections were less frequent and less likely to recur than HSV-2 infections. Fifteen per cent of primary first episodes were caused by HSV-1, as compared with 3 per cent of nonprimary first episodes and 2 per cent of recurrent episodes. Moreover, during follow-up of first-episode patients, only 14 per cent of HSV-1 infections recurred, as compared with 60 per cent of HSV-2 infections. Recurrences were more likely to follow an index recurrent episode than an index first episode, whether primary or nonprimary, and were more likely to occur in men than in women. Among patients with primary HSV-2 infections, the probability of recurrence was directly related to the presence and titer of neutralizing antibody to HSV-2 in convalescent-phase serum.