The association between HPV,intraepithelial lesions and HIV-1 shedding in anogenital specimens in two contrasting populations: Senegalese women and American MSM

Abstract

In light of observational evidence showing an association between human papillomavirus (HPV) and HIV acquisition risk, the potential of HPV vaccination as a HIV prevention strategy is being considered. However, the relationship between HPV and HIV infectiousness is unclear. In this analysis, the relationship between HPV and anogenital HIV shedding (a proxy for transmissibility) was assessed in two diverse populations: HIV-infected Senegalese women and American men who have sex with men (MSM). Data from two longitudinal studies with similar protocols were analysed. In both studies, anogenital specimens underwent cytologic, HPV DNA, and HIV-1 RNA testing. Analyses utilised multivariable generalised estimating equations that controlled for age, hormonal contraceptive use (women only), plasma viral load, CD4 count and treatment status. Among Senegalese women, cervical lesions were significantly associated with the detection of HIV RNA (aRR = 1.16 [1.05, 1.28]) and log10 cervicovaginal fluids viral load (adjusted β = 0.56 [0.12, 1.01]). No association was detected between HPV (of any type) and cervicovaginal HIV shedding (aRR_Detection = 0.90 [0.77, 1.06]; β_Quantity = −0.31 [−0.78, 0.16]). Among MSM, having multiple HPV infections (versus no HPV infection) was associated with anal HIV shedding (aRR_Detection = 1.05 [1.01, 1.09]; β_Quantity = 0.11 [0.01, 0.21]). Anal lesions were not associated with anal HIV shedding (aRR_LESIONS = 0.99 [0.96, 1.03], β_LESIONS = −0.05 [−0.13, 0.03]). Although HPV and intraepithelial lesions were associated with anogenital HIV shedding in crude analyses, the measures of effect were attenuated in adjusted analyses. Our data suggest that the prevention of HPV through vaccination is unlikely to substantially affect HIV infectiousness among persons living with HIV.

Keywords

HIV AIDS sexually transmitted infection cervical dysplasia human papillomavirus vaccination viral shedding prevention human immunodeficiency virus

Introduction

Immunodeficiency disorders, including HIV, are a risk factor for persistent human papillomavirus (HPV), HPV-associated lesions, and cervical and anal cancers.^1–4 Recent observational data show that HPV infection is associated with increased risk for acquisition of HIV, which has prompted interest in the potential of including HPV vaccination in HIV prevention programmes.^5,6 The influence of HPV on HIV infectiousness, however, is not well understood. With HIV transmission risk largely a function of the amount of virus present in anogenital fluids,^7–11 we considered anogenital HIV shedding as a proxy for HIV infectiousness. Only a small number of studies have assessed the relationship between HPV infection and anogenital HIV shedding and these yielded inconsistent results.

Spinillo et al. detected a significant relationship between HIV shedding in cervicovaginal fluids (CVF) and HPV infection¹² and cervical lesions,¹⁰ even after adjustment for CD4 counts, HIV plasma viral load and antiretroviral therapy (ART). Kovacs et al.⁸ detected a significant relationship between HPV and HIV shedding in CVF in unadjusted analyses, though it was attenuated and lost significance when adjusted for HIV plasma viral load. When this relationship was assessed by Fornabaio et al.¹³ no association was detected in unadjusted analyses. Kiviat et al. assessed this relationship in pre-ART era men who have sex with men (MSM) and reported a non-significant relationship between HPV and detection of anorectal HIV RNA.¹⁴

To help inform current discourse pertaining to HPV vaccination and HIV prevention, we evaluated how HPV and associated lesions were related to HIV shedding in anogenital fluids in two contrasting populations of HIV-1 infected persons: ART-naïve Senegalese women and American MSM with varying exposures to ART.

Methods

Study populations

This secondary data analysis utilises data from two studies with similar protocols of persons living with HIV (PLWH), summarised in Table 1 and described previously.^15,16 Data collection in Senegal was conducted between 1994 and 1998. Briefly, women aged 15 years and older who presented to an outpatient infectious disease clinic in Dakar, Senegal were offered HIV testing. Women who tested positive (n = 433) were invited to enroll into a cohort study that assessed the effect of HIV on risk of cervical neoplasia. The current analysis assessed a subset of women who were HIV-1 infected and who had cervicovaginal samples for HIV RNA quantification (n = 169). Follow-up visits were scheduled for every four months, with a mean follow-up period of one year. A total of 302 study visits were completed. Since data were collected prior to the availability of ART in Senegal, all enrolled women were ART naïve. The study protocol was approved by the Institutional Review Boards (IRB) of the Universities of Washington and Dakar and the Senegalese National AIDS Committee; written informed consent was obtained from all study participants.

Table 1.

Comparison of study methods.

	Senegalese HIV-1 infected women		American HIV-1 MSM
Recruitment setting	Dakar, Senegal Infectious disease/primary care clinics		Seattle, USA Infectious disease/primary care clinics & gay media ads
Enrolment period	1994–1998		1996–1997
Specimen collection	Blood	Viral load, CD4	Blood	Viral load, CD4
	Cervicovaginal fluids	HPV DNA HIV RNA	Anorectal swabs	HPV DNA HIV RNA
			Anorectal swabs	HPV DNA HIV RNA
	Pap Smear	Cytology		Cytology
ART status	All ART-naïve		Varied
Number enrolled	169 women/302 visits		333 MSM/2346 visits
Mean follow-up	∼1 year		∼2.5 years
IRB approvals	University of Washington University of Dakar Senegalese National AIDS Committee		University of Washington

The primary objective of the cohort study in Seattle was to assess HPV, intraepithelial neoplasia, and HIV expression in the anorectal canal. HIV-1 positive MSM (n = 333) were enrolled in the Seattle study between July 1996 and January 1997. Participants were recruited through primary care and infectious disease clinics and advertisements in gay media. Follow-up visits were scheduled every four months for up to six years, finally concluding in September 2002 after 2346 study visits had occurred. Half of the cohort initiated ART during the study observation period; only 20% of the cohort had no record of ART during the study observation period. The study protocol was approved by the University of Washington IRB; written informed consent was obtained from all study participants.

Specimen collection and laboratory procedures

During baseline and follow-up visits, blood specimens, CVF specimens (women), anorectal swabs (men) and cervical Pap smears (women) were obtained from study participants. Women were instructed to schedule study visits when they were not menstruating. CVF specimens were obtained from women by inserting a speculum and irrigating the vaginal and cervical area with 5 ml of sterile saline. Among men, anorectal mucosa specimens were obtained through the insertion and rotation of two dry Dacron swabs (in succession) in the anal canal and lower rectal mucosa, ensuring that both the lower rectal mucosa and anal squamous epithelium were sampled. The first swab was placed in 1 ml RNA reagent (Ultraspec; Biotecx Laboratories, Houston, TX, USA) and used for an anal Pap smear. The second swab was placed in specimen transport medium (STM; Digene Diagnostics, Silver Spring, MD, USA) and used for DNA and RNA assays. In both studies, blood was collected in ethylenediaminetetraacetic acid (EDTA) tubes.

The same procedures for evaluating HPV, Pap smears and CD4 counts were utilised in both studies. As described previously,¹⁷ polymerase chain reaction (PCR) assays for the detection of HPV DNA were performed with HPV L1 consensus primers MY09/11 and hybridisation with a generic HPV probe and mixture of HPV type-specific oligonucleotide probes for high-risk HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52 or 56. Subsequently, positive samples were re-amplified to assess the presence of nine HPV types in groups: for low-risk HPV types (i.e. combined HPV 6 and 11), for high-risk HPV types (i.e. HPV 16, HPV 18, HPV 45 and a combined HPV 31, 33, 35 and 39). Beginning 1 April 1998, HPV detection and typing analyses were performed via Roche reverse line blot test method (Roche Molecular Systems, Alameda, CA) with probes for 27 HPV types, including low-risk HPV types 6, 11, 40, 42, 53, 54, 57, 66 and 84 and high-risk HPV types 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 55, 56, 58, 59, 68, 73, 82 and 83. Pap and anal smears were stained, interpreted and classified according to the Bethesda System as unsatisfactory, negative, atypical squamous cells of uncertain significance (ASCUS), low/high grade squamous intraepithelial lesion (LSIL/HSIL) or invasive cancer.

The two studies utilised similar lab methods to evaluate HIV RNA present in CVF, anorectal and blood specimens. CVF specimens were tested for occult blood using a hemastix strip, and, if positive, were not evaluated for HIV RNA detection and quantification.¹⁶ HIV viral loads were evaluated by extracting HIV RNA from specimens using Amplicor HIV-1 Monitor test (Roche Molecular Systems, Pleasanton, CA, USA), which has a minimum detection limit of 80 copies/ml. Samples that had negative results for the quantitative assay subsequently underwent qualitative assessment, which had a lower limit detection of 40 HIV RNA copies/ml. The FACSCount analyser (Becton Dickinson Biosciences, San Jose, CA) was used to determine the number of CD4 cells per µl of blood.

Statistical methods

The analysis was limited to study visits containing qualitative and/or quantitative data on the presence of HIV-1 RNA in CVF (302 study visits from 169 women) and in anorectal swabs (2346 study visits from 333 MSM). Two outcomes formed the basis of this analysis: (1) detection of (any) HIV RNA and (2) HIV viral load (measured in log₁₀ copies of RNA/ml). Samples that were positive by the more sensitive qualitative HIV-1 RNA assay but negative by the less sensitive quantitative assay were assigned a quantitative value of 0.5 log copies/ml, which is a value that would be below level of quantification. The association between HPV and anogenital HIV shedding was evaluated in four respects:

Presence/absence of HPV: dichotomous variable.

Number of HPV types detected: no HPV infection, one type and two or more types.

HPV risk type: no HPV detected, detection of non-typed or low-risk HPV infection (and no other type), detection of a high-risk HPV infection (excluding types 16 or 18) and detection of types 16 or 18 (with or without co-infection with other types).

Changes in HPV status since last visit (MSM only): HPV infection at the prior and current visit (persistent HPV infection, +/+), prior but not current visit (HPV clearance, +/−), not prior but current visit (incident HPV infection, −/+) and neither prior nor current visit (no HPV infection, −/−).

This last assessment of HPV could only be conducted with the MSM sample, as this study comprised considerably more visits (and more longitudinal visits per subject) than the Senegal study; the analyses of this variable were restricted to non-baseline visits.

Baseline data were utilised from each sample to evaluate the crude association between HPV and intraepithelial lesions and anogenital HIV shedding. We used bar graphs to illustrate how the distribution of log HIV viral load in anogenital specimens varies in the presence of HPV or intraepithelial lesions. Chi square statistics were used to evaluate statistical significance.

To account for intra-subject correlation, multivariable generalised estimating equations (GEE) were used for all analyses. The following variables were included in all multivariable models as potential confounders: age, CD4 count and plasma HIV-1 viral load. Hormonal contraceptive use was included in the models of Senegalese data; ART use was included in the models of American data. For multivariate models evaluating the association between HPV and anogenital HIV shedding, we controlled for genital abnormalities and potential markers of genital infections that were indicated in genital exam records; for women, this included cervical discharge, genital ulcers and herpes; for MSM, this included anal fissures, mass and hemorrhoids.

In light of the frequent occurrence of the outcome of interest, local HIV-1 shedding, we used relative risk regression to model factors associated with detection of HIV-1 RNA in anogenital specimens. Specifically, risk ratios were estimated using a Poisson working correlation model and exchangeable correlation structures.¹⁸ GEE with Gaussian links and exchangeable correlation structures were used to model the mean viral load in anogenital specimens (log₁₀ copies of HIV-1 RNA per ml) as a function of the predictors of interest. Since the distribution HIV viral load was non-normally distributed for American MSM (see Figure 1), we compared the results from the model when it utilised all study visits versus only study visits in which the participant had detectable HIV RNA in their blood specimen (Table 4).

Figure 1.

Association between HPV and log HIV viral load in anogenital specimens at baseline visit. (a) HIV viral load in cervicovaginal fluids, by number of HPV types detected: Senegalese women at baseline visit. (b) HIV viral load in anorectal specimens, by number of HPV types detected: American MSM at baseline visit.

Results

Baseline characteristics of study samples

The Senegalese women and American MSM samples differ in several important respects (see Table 2). The mean age was younger in the Senegalese sample than the MSM sample (32.1 vs. 39.5). Whereas all of the Senegalese women were ART-naive for the entirety of the observation period, 29% of the MSM were on ART at study enrollment, 51% initiated ART during the study observation period and 21% remained ART-naive for the entirety of their observation. Participants in both studies, and especially in the Senegalese study, exhibited baseline indicators of advanced disease: average CD4 counts were 301 and 439 cells per µl, percent with detectable plasma HIV viral load was 99% and 73%, and percent with detectable HIV viral load in anogenital specimens was 80% and 33% among women and men, respectively. Among women, the median HIV plasma viral load was 5.1 log₁₀ copies/ml (IQR = 4.3, 5.7); median HIV CVF viral load was log₁₀ 2.3 copies/ml (IQR = 0.5, 3.2). Among men, the median HIV plasma viral load was log₁₀ 3.5 copies/ml (IQR = undetectable (UD), 4.5); median HIV anorectal viral load was log₁₀ 0.6 copies/ml (IQR = UD, 0.8). The majority of both study groups had prevalent HPV infections (65% of women and 93% of men) at baseline; HPV types 16 and/or 18 were more commonly detected in men than women (59% vs. 21%). LSIL and HSIL were diagnosed as baseline in 19% and 3% of women; 46% and 3% of men had an LSIL and HSIL diagnosis at baseline visit. Male participants had, on average, a longer period of follow-up and more study visits than women (mean number of visits: 5.1 vs. 2.9; mean length of follow-up: 2.5 years vs. one year).

Table 2.

Baseline characteristics of study participants.

	Senegalese women (n = 169)	American MSM (n = 333)
Number of study visits, mean (SD)	2.9 (2.3)	5.1 (1.6)
Age, mean (SD)	32.1 (7.7)	39.5 (7.8)
Hormonal contraceptive use, number (%)	12 (7.1)	–
ART status, number (%)
On ART at study enrollment	0 (0)	95 (28.5)
Initiated ART during observation period	0 (0)	169 (50.8)
Never on ART during observation period	169 (100.0)	69 (20.7)
CD4 count, mean (SD)	301.3 (251.4)	439.4 (265.5)
Detectable HIV RNA, number (%)
In blood plasma	165 (98.8)	247 (73.3)
In anogenital specimens	135 (79.9)	107 (32.5)
Log HIV RNA viral load, median copies/ml (IQR)
In blood plasma	5.1 (4.3, 5.7)	3.5 (0, 4.5)
In anogenital specimens	2.3 (0.5, 3.2)	0.6 (0, 0.8)
Detection of HPV DNA, by risk type
None detected	53 (35.3)	23 (7.4)
Low-risk type(s) (only)	30 (20.0)	36 (11.7)
High-risk type(s), excluding types 16/18	36 (24.0)	67 (21.7)
Types 16/18, including other types	31 (20.7)	183 (59.2)
Pap smear results, number (%)
Normal	91 (55.8)	127 (40.7)
ASCUS	37 (22.7)	33 (10.6)
LSIL	31 (19.0)	142 (45.5)
HSIL	4 (2.5)	10 (3.2)

Crude association between HPV, intraepithelial lesions and HIV shedding at baseline

Figures 1(a) and (b) display the distribution of log HIV viral load in anogenital specimens by the number of HPV types detected in each study population. In MSM, but not Senegalese women, significant differences existed in the distribution of the log HIV viral load across HPV exposure categories. The percent with detectable HIV viral load in anogenital specimens was 19%, 21% and 40% for men with no HPV, a single HPV type, and multiple HPV types, respectively, (p = 0.001). In women, the percent of participants with detectable HIV viral load in CVF specimens was 77%, 83% and 86% for women with no HPV, a single HPV type, and multiple HPV types, respectively, but these differences were not significantly different (p = 0.613).

Figures 2(a) and (b) display the distribution of log HIV viral load in anogenital specimens in the presence and absence of intraepithelial lesions in each study population. In both samples, a smaller proportion of participants with intraepithelial lesions, compared to those with normal or ASCUS Pap smear results, had an undetectable HIV viral load in their anogenital specimen (women: 7% vs. 23%, p = .06; men = 61% vs. 76%, p = 0.005).

Figure 2.

Association between intraepithelial lesions and log HIV viral load in anogenital specimens at baseline visit. (a) HIV viral load in cervicovaginal fluids, by cervical Pap result: Senegalese women at baseline visit. (b) HIV viral load in anorectal specimens, by anal Pap result: American MSM at baseline visit.

Adjusted association between HPV, intraepithelial lesions and HIV shedding

For the sample of Senegalese women, HPV was assessed in multivariate models as a dichotomous variable, a three-level variable indicating the number of HPV types present and a four-level variable indicating HPV risk type. Regardless of how HPV exposure was defined, it was not independently associated with detection of HIV in CVF specimens (dichotomous outcome) or HIV viral load in CVF (continuous outcome) in multivariate models (see Table 3). Cervical lesions, however, were significantly associated with having detectable HIV RNA in CVF (aRR_LSIL = 1.17, 95% CI = 1.05, 1.31; aRR_HSIL = 1.21, 95% CI = 1.06, 1.37). Women with cervical lesions, on average, had a greater HIV log₁₀ viral load than women without lesions (β_LSIL = 0.54, 95% CI = 0.07, 1.02; β_HSIL =1.01, 95% CI = 0.13, 1.89; see Figure 1).

Table 3.

Association between HPV, cervical lesions and cervicovaginal HIV shedding among ART-naive women in Senegal.

	Percent shedding at baseline	aRR (95% CI)	Adjusted β (95% CI)
Any HPV infection
No HPV	77.4	1.00	–
HPV infection	83.5	0.90 (0.77, 1.06)	−0.31 (−.78, 0.16)
Number of HPV types
0	77.4	1.00	–
1	82.6	0.90 (0.75, 1.08)	−0.28 (−0.82, 0.25)
2+	85.7	0.91 (0.77, 1.07)	−0.18 (−0.80, 0.45)
HPV risk type
Negative – no HPV infection	77.4	1.00	–
Low-risk types	80.0	0.85 (0.68, 1.06)	−0.46 (−1.12, 0.20)
High-risk (non 16/18)	75.0	0.89 (0.75, 1.06)	−0.38 (−0.96, 0.19)
Types 16/18	96.8	1.03 (0.90, 1.19)	0.03 (−0.52, 0.58)
Pap smear results
Normal	73.3	1.00	–
ASCUS	96.0	1.05 (0.85, 1.30)	0.17 (−0.44, 0.78)
LSIL	91.7	1.17 (1.05, 1.31)	0.54 (0.07, 1.02)
HSIL	100.0	1.21 (1.06, 1.37)	1.01 (0.13, 1.89)

Note: All analyses adjusted for age, plasma viral load, CD4 count; HPV analyses also controlled for herpes, genital ulcers, and cervical discharge.

For the sample of American MSM, there were a couple of signals that HPV may be independently associated with anal HIV shedding (see Table 4). Having an incident HPV infection (vs. no HPV infection at current or prior visit) was associated with a greater mean HIV viral load in anogenital specimens (β = 0.19, 95% CI = 0.01, 0.36). Having multiple HPV types (vs. no HPV infection) was associated with a greater likelihood of anal HIV shedding (RR = 1.05, 95% CI = 1.01, 1.09) and greater mean HIV viral load in anogenital specimens (β = 0.11, 95% CI = 0.01, 0.21). Having a high-risk (non 16/18) HPV type was associated with a greater mean HIV viral load in anogenital specimens (β = 0.15, 95% CI = 0.04, 0.26). Anal intraepithelial lesions, however, were not significantly associated with anal HIV shedding.

Table 4.

The association between HPV, anal lesions and anal HIV shedding among men who have sex with men in Seattle.

			All visits	Only visits with detectable plasma viral load (n = 1320)
	Percent shedding at baseline	aRR (95% CI)	Adjusted β (95% CI)	Adjusted β (95% CI)
Any HPV infection
No HPV	21.7	1.00	–	–
HPV infection	31.3	1.03 (0.99, 1.06)	0.08 (−0.01, 0.17)	0.13 (−0.05, 0.31)
HPV over time	N/A
No HPV at current or prior visit		1.00	–	–
HPV at prior but not current visit		1.00 (0.95, 1.06)	−0.09 (−0.20, 0.02)	−0.21 (−0.43, 0.01)
HPV at prior and current visit		1.03 (0.98, 1.08)	0.05 (−0.07, 0.17)	0.02 (−0.24, 0.28)
New infection at current visit		1.06 (0.99, 1.14)	0.19 (0.01, 0.36)	0.31 (−0.03, 0.65)
Number of HPV types
0	19.1	1.00	–	–
1	21.4	1.00 (0.97, 1.03)	0.04 (−0.06, 0.14)	0.07 (−0.13, 0.27)
2+	39.7	1.05 (1.01, 1.09)	0.11 (0.01, 0.21)	0.17 (−0.03, 0.37)
HPV Risk Type
Negative – no HPV infection	21.7	1.00	–	–
Low-risk types	27.8	1.02 (0.98, 1.06)	0.16 (−0.07, 0.39)	0.25 (−0.12, 0.63)
High-risk (non 16/18)	25.4	1.04 (0.99, 1.08)	0.15 (0.04, 0.26)	0.24 (0.02, 0.47)
Types 16/18	36.1	1.02 (0.98, 1.06)	0.04 (−0.06, 0.14)	0.08 (−0.11, 0.27)
Anal Pap smear results
Normal	21.4	1.00	–	–
ASCUS	33.3	1.00 (0.95, 1.04)	−0.05 (−0.13, 0.06)	−0.04 (−0.21, 0.14)
LSIL	37.8	1.01 (0.97, 1.05)	0.02 (−0.07, 0.10)	0.04 (−0.09, 0.17)
HSIL	45.5	1.00 (0.96, 1.05)	0.09 (−0.09, 0.26)	0.22 (−0.10, 0.54)

Note: All analyses adjusted for age, plasma viral load, CD4 count, HAART status; HPV analyses also controlled for clinically documented presence of anal fissures, hemorrhoids and anal mass.

Discussion

In these two samples of ART-naïve Senegalese women and American MSM with varying exposure to ART, HPV and intraepithelial lesions appeared associated with anogenital HIV shedding in crude analyses. When adjusted for plasma viral load and other factors, the association with anogenital HIV shedding was greatly attenuated. In women, HPV detection was not independently associated with cervicovaginal HIV shedding, though cervical lesions were moderately associated with cervicovaginal HIV shedding. In MSM, incident detection of HPV, high-risk HPV types (non 16/18), and having multiple HPV types were slightly associated with anal HIV shedding; anal lesions were not associated with anal HIV shedding.

The MSM study was better powered to detect associations of small magnitude, which might partially explain why some of the HPV analyses were significant for MSM but not for the Senegalese women. While significant, the signals of association between HPV and HIV shedding were of small magnitude and would not have been significant had we adjusted our analyses for multiple comparisons. It is noteworthy that only more severe categorisations of HPV were associated with anal HIV shedding, which might be indicative of reverse causality: inadequate HIV control may impair the immunological response to HPV.

The findings from the Senegalese data are consistent with existing literature, which has described a relationship between cervical lesions and HIV shedding¹⁰ and yet a lack of association between non-type-specific HPV and HIV shedding in crude¹³ and adjusted⁸ analyses. The greater tendency of cervical lesions (relative to HPV) to elicit a local inflammatory response^9,13,19,20 lends biological plausibility to our observation that cervical lesions, but not HPV infection more generally, were associated with local HIV shedding. However, reverse causation might also underlie the observed relationship: women with poorer control of HIV (as evidenced by local HIV shedding) might be more likely to develop cervical lesions.

While the Senegalese data provide evidence that the prevention of cervical lesions through HPV vaccination might theoretically affect local HIV shedding in HIV-positive women, there are several reasons to give pause. First, the effect size corresponding to LSIL was modest; and while the effect size was larger for HSIL, less than 3% of the sample was diagnosed with HSIL. Second, no association was observed between anal lesions and HIV shedding in the MSM sample, which was comprised of much healthier individuals. It is plausible that the observed association between intraepithelial lesions and anogenital shedding might only exist among patients in extremely poor health.

There are limitations to this analysis. Both studies were conducted in the late-1990s/early-2000s, an era of limited/no ART availability and high morbidity and mortality, which might limit the generalisability of our results to current PLWH populations. Laboratory-confirmed sexually transmitted infections could not be evaluated as potential confounders, as data on these co-morbidities were incomplete. Instead we controlled for symptoms of genital infection in the multivariate analyses of Senegal data and anal abnormalities in the American MSM data. In this exploratory analysis, we evaluated multiple statistical tests inflating the risk of Type 1 error. CVF fluids (Senegal study) versus anal swabs suspended in STM (American study) were evaluated for HPV DNA and HIV RNA; this protocol difference might have detrimentally affected the cross-study comparisons. Our reliance on Pap smears, a screening approach known to have low sensitivity, to evaluate the presence of cervical and anal lesions might have resulted in non-differential misclassification of lesion status, which would attenuate the estimates of association in our study. Finally, both studies imperfectly addressed the issue of blood contamination of anogenital specimens: the number of CVF samples that were excluded due to the presence of blood is unknown (Senegal study), and anorectal specimens were not evaluated for the presence of blood (MSM study). It is unclear whether, if at all, these sources of bias impacted the results of this analysis.

In these two samples of Senegalese women and American MSM, we did not observe a strong independent association with local HIV shedding. Though cervical lesions were associated with local HIV shedding in ART-naive women, anal lesions were unassociated with HIV shedding in healthier, ART-experienced MSM, perhaps indicative of the far-reaching effects of ART. Our data suggest that the prevention of HPV through vaccination is unlikely to substantially affect HIV infectiousness among PLWH. Prevention of intraepithelial lesions through HPV vaccination (or other means) may only affect HIV transmission in settings where ART is not widely utilised by PLWH. The potential of HPV vaccination to prevent HIV acquisition remains unclear and warrants further investigation.

Footnotes

Acknowledgements

We thank Jane Kuypers, Diouana Ba and Haby Agne for their work in the laboratories in Senegal and Seattle, and John Lin and Alison Starling for questionnaire development and data management. We also thank Tom Lampinen for study coordination and Paul Nelson for patient care in the MAH study cohort in Seattle. Finally, we thank the women who participated in this research in Senegal and the men who participated in the MAH study in Seattle.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Supported by grants from the National Institutes of Health (AI37466, CA62801).

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