DOES MATERNAL HSV-2 INFECTION INCREASE RISK OF INTRA-PARTUM TRANSMISSION OF HIV-1? Frances M Cowan, Jean Humphrey, Robert Ntozini, Kuda Mutasa, Peter Iliff

Herpes simplex virus type 2 infection Role of HSV-2 on sexual acquisition and transmission of HIV How HSV-2 might effect intra-partum HIV transmission Zvitambo study Nested case control study to examine the role of HSV-2 in MTCT of HIV Implications

Herpes simplex virus type 2 - the cause of genital herpes Sexually transmitted Commonest cause of genital ulceration Infection may be symptomatic (65%) or asymptomatic (35%) Only one third of those infected are aware of diagnosis Following infection the virus becomes latent, periodically reactivating to cause recurrences. HIV and HSV-2 co-infection results in more frequent and severe recurrences Aciclovir suppresses genital herpes reactivation

What explains the variability in rates of HIV infection in Africa? 4 Cities Study – 2 cities in West Africa (low HIV prevalence) - 2 cities in East Africa (high HIV prevalence) AIDS 2001; 15: S15-30

Ndola HIV-1: 32% W, 24% M HSV-2: 55% W, 36% M Yaounde HIV-1: 7% W, 3.6% M HSV-2: 51% W, 27% M Kisumu HIV-1: 29% W, 18% M HSV-2: 68% W 35% M Cotonou HIV-1: 2.8% W, 2.8% M HSV-2: 30% W, 12% M

What explains the variability in rates of HIV infection in Africa? Circumcision HSV-2 infection  Sexual behavior not very different AIDS 2001; 15: S15-30

HSV-2 and sexual acquisition of HIV-1 Sexual acquisition of HIV-1 is likely increased by presence of HSV-2 infection (AIDS 2006) Meta-analysis of 19 studies suggests that prevalent HSV-2 infection increases risk of acquisition in men (adjusted RR 2.7 [95% CI ]) and women (aRR 3.1 [95% CI ]. Studies looking at effect of incident HSV-2 infection are less methodologically sound. Intervention trials ongoing to see if suppressing HSV-2 infection with antiviral drugs can reduce this risk. (HPTN 039 and Mwanza Herpes Trial)

Effect of HSV-2 on sexual transmission of HIV Much less data than for acquisition Very few studies on HIV transmission overall Relatively few events observed Risk factors: high viral load, more advanced HIV disease or primary disease, Genital Ulcer Disease Only one study which has looked at effect of HSV-2 on sexual transmission of HIV

HSV-2 and sexual transmission of HIV-1 Genital ulceration increases risk of transmission five fold Per contact risk = vs for those without genital ulceration, p=0.002 HSV-2 seropositivity per se not associated with increased transmission risk. Lancet 2001;357:

How does HSV-2 facilitate sexual HIV-1 transmission? Increased genital shedding of HIV from both clinical and sub-clinical HSV-2 lesions (JAIDS 2003; 33: AIDS 2002;16: ) Possibly by increasing HIV-1 plasma viral load (Nagot et al CROI. 2006)

Intra-partum transmission of HIV Maternal health Obstetric factors Infant prematurity Linear relationship between maternal plasma HIV-1 viral load and risk of transmission

Intra-partum transmission - 2 Role of STIs in intra-partum transmission unclear. Presumptive treatment of bacterial STIs does not reduce risk of intra-partum transmission. (Am J Ob Gyn 2005;185: ) No data on whether HSV-2 infection increases risk of intra-partum transmission of HIV-1 Clinical genital herpes during pregnancy is associated with increased transmission risk (adj OR 4.8 (95%CI ). (Obst Gynec 2005;186:1341-8)

Pre-ARV era MCTC rates ACTG % (95%CI ) European collaborative study % (95% CI %) Sub-Saharan Africa 35-50%

Rates of HSV-2 vary globally NHANES % of adults in the USA infected. Higher rates among women and African-American women. European studies show sero-prevalences of 2-6% (higher in Eastern Europe) Rates in sub-Saharan Africa are high

Seroprevalence of HSV-2 in Tanzania JID 1999; 179:16-24

DOES MATERNAL HSV-2 INFECTION INCREASE RISK OF INTRA-PARTUM TRANSMISSION OF HIV-1?

Zvitambo Study Randomised placebo controlled trial Aimed to discover if giving Vitamin A to mothers and babies in the immediate post-partum period i)improved infant mortality ii)reduced risk of mother to child transmission of HIV-1 through breast feeding iii)reduced the risk of women acquiring HIV-1 in the year after delivery. Recruitment took place in Harare, Zimbabwe from November 1997 to January 2000.

Trial design 14,110 mother-baby pairs recruited Included 4,495 HIV-1 positive mothers HIV-1 positive mothers and their babies had blood taken at baseline, 6 weeks, 3 months then 3 monthly for 2 years Where available specimens were archived from each visit

Objectives of nested case control study To see if: women with prevalent HSV-2 infection at delivery had an increased risk of intra-partum transmission of HIV-1; women who acquired HSV-2 antibodies within 6 weeks of delivery had an increased risk of intra- partum transmission of HIV-1; women with serological evidence of active syphilis at delivery had an increased risk of intra- partum transmission. Case control study using archived sera

Case control study design Cases: 509 HIV+ve women whose babies were presumed HIV infected intra-partum (baby HIV PCR-negative at delivery and PCR-positive at 6 weeks) Controls: 1018 HIV-positive women whose babies remained PCR-negative at 1 year

Power If 80% of controls group are co-infected with HSV-2, the study had > 90% power to detect a 50% increase in the risk of intra-partum transmission. If incidence of HSV-2 is 1% in the control arm the study has 80% power to show that incident HSV-2 increases the risk of intra-partum by a factor >3.

Testing strategy Maternal serum taken within 96 hours of delivery was tested for HSV-2 antibody –HerpeSelect (Focus Diagnostics) –Low +ves / indeterminates re-tested using HerpeSelect –Those remained LP/Ind re-tested using western blot (11%) –Those remained LP/Ind re-tested using Biokit Elisa –Random sample of positives and negatives retested using western blot and Biokit Elisa 6 week samples were tested for HSV-2 if HSV-2 seronegative at delivery and for syphilis (RPR and TPHA).

1527 women selected (509 cases and 1018 controls) Baseline FocusELISA 1127 positive 193 negative 4 indeterminate 162 low positive Retested by: Western blot & BioELISA 1195 positive 253 negative 4 indeterminate 34 low positive Final baseline result Missing Pos Neg Ind Total Missing Pos Neg Ind Total W es ter nb lot BIOELISA 18 cases and 23 controls insufficient baseline sample HSV-2 Testing Flowchart: determination of baseline HSV-2 result

Results Overall 82.5% [95% CI ] of (HIV positive) women were HSV-2 antibody positive Baseline Characteristics –Cases were less educated, and had more signs of advanced HIV-1 disease (lower CD4 count, lower haemoglobin, higher viral load, smaller arm circumference) and to have to lower birth weight babies than controls.

Effect of prevalent HSV-2 infection Cases were more likely than controls to be HSV-2 infected (unadj OR 1.49 [95% CI , p=0.01]) Cases were more likely than controls to be HSV-2 infected after adjusting for factors assoc d with intra- partum transmission (adj OR1.50 [95% CI , p=0.014]) The proportion of HIV-1 intra-partum transmission potentially attributable to maternal HSV-2 infection at time of delivery was 28.4% [95% CI ]

Sensitivity analyses Re-analysing data using differing testing algorithms for HSV-2 diagnosis did not change direction of effect but did alter significance of results HerpeSelect + WB only (unadj OR 1.27 [95% CI ], p=0.15, adj OR 1.28 [95% CI ], p=0.17). HerpeSelect + BioElisa only, (unadj OR 1.36 [95% CI ], p=0.03, adj OR 1.31 [95% CI ], p=0.08].

Effect of ‘incident’ HSV-2 infection 27 / 158 women who were HSV-2 negative at delivery had ‘seroconverted’ to HSV-2 by 6 weeks (17.3%, 95% CI ) ‘Sero-conversion’ was associated with an increased risk of HIV-1 transmission although not significant (unadj OR 1.59 [95% CI , p=0.29]; adj OR 1.44 [95% CI , p=0.44]

Effect of syphilis 52 of 1289 women had evidence of active syphilis at 6 weeks (4.0%, 95% CI ). Unadj OR of intra-partum transmission associated with syphilis = 0.89 [95% CI , p=0.68] Adj OR 0.63 [95% CI , p=0.16]

Conclusion HSV-2 is common among HIV positive women of child bearing age in Zimbabwe Maternal HSV-2 is associated with an increased the risk of intra-partum transmission of HIV Maternal seroconversion to HSV-2 is common and needs to be better defined. Syphilis is not associated with an increased risk of intra-partum transmission of HIV

Implications Adding HSV-2 interventions to existing PMTCT programmes might further reduce intra-partum transmission of HIV Unlikely to be worthwhile if using HAART but may have a significant impact where PMTCT uses nevaripine only approach Trial of adding suppressive aciclovir to nevaripine only PMTCT may be warranted?