Current Concepts for Genital Herpes Simplex Virus Infection: Diagnostics and Pathogenesis of Genital Tract Shedding

Abstract

Herpes simplex virus 2 (HSV-2) is a DNA virus that is efficiently transmitted through intimate genital tract contact and causes persistent infection that cannot be eliminated. HSV-2 may cause frequent, symptomatic self-limited genital ulcers, but in most persons infection is subclinical. However, recent studies have demonstrated that the virus is frequently shed from genital surfaces even in the absence of signs or symptoms of clinical disease and that the virus can be transmitted during these periods of shedding. Furthermore, HSV-2 shedding is detected throughout the genital tract and may be associated with genital tract inflammation, which likely contributes to increased risk of HIV acquisition. This review focuses on HSV diagnostics, as well as what we have learned about the importance of frequent genital HSV shedding for (i) HSV transmission and (ii) genital tract inflammation, as well as (iii) the impact of HSV-2 infection on HIV acquisition and transmission. We conclude with discussion of future areas of research to push the field forward.

FIG 1

Estimates of the number of people with prevalent HSV-2 infection in 2012, by age, sex, and region. (Adapted from reference .)

FIG 2

The majority of shedding episodes last less than 24 h. HSV DNA was quantified by PCR from self-collected genital swabs taken by a cohort of participants every 6 h for 60 days. Overall, the duration of a shedding episode is associated with viral titer. (Adapted from reference with permission of Oxford University Press.)

FIG 3

Anatomic distribution of genital shedding in 2 women who had 22 genital samples collected over a 30-day period. The quantity of virus shed in each region is shown according to the heat map. (A) Widespread genital shedding in a woman with asymptomatic shedding. (B) Diffuse shedding in a woman with a symptomatic genital lesion on days 1 to 5, days 11 and 12, and days 15 to 19. The site of the lesion is highlighted in black. (Adapted from reference .)