Molecular Characterization of Human Papillomavirus Infections and Associated Cell-Mediated Immune Responses among Fishermen Co-Infected With HIV and HSV-2 in Kisumu, Kenya

Abstract

Persistent HPV infection is associated with cervical, vulvar, anal and penile cancers. High incidence rates of these cancers are observed in Africa compared to other parts of the world, with HIV co-infection exacerbating the natural course of HPV infections, and HSV-2 infection linked to HIV acquisition. Although, these three viral infections are highly prevalent in the fishing communities, there is limited data on the incidence of HPV, HIV and HSV-2 among fishermen in Kisumu, Kenya. Additionally, HPV genotypic interactions (type competition) and associated cell-mediated immune responses have not been evaluated among fishermen. This study sought to carry out molecular characterization of genotypic HPV infections, cytokine immune responses against HPV infection, HIV/HSV-2 co-infections, and the associated risk factors among fishermen around Lake Victoria in Kisumu, Kenya. Three hundred fishermen were followed-up every three months for 12 months. Socio-demographic data was collected using a structured questionnaire. Genital swabs for HPV testing as well as blood for immune response assays and HIV/HSV-2 serology were collected. HPV infection was determined using PCR, cell-mediated cytokine responses evaluated by Luminex assay and statistical analyses performed using Stata version 12. Baseline HPV prevalence was 49.7% and incidence was 53.5%. Factors associated with HPV prevalence were: lack of circumcision aOR=2.38 (95% CI: 1.18 – 4.77), history of STI (aOR=3.25; 95% CI: 1.63–6.14) and HIV infection (aOR=2.43; 95% CI: 1.10–5.37). Consistent condom use and being single were protective. Factors associated with HPV incidence were: baseline HPV infection (aRR=9.35; 95% CI: 3.03–28.90) and multiple partners (aRR=14.50; 95% CI: 1.70–31.58). Condom use was protective. HPV persisted in 86% of fishermen and factors associated with HPV persistence were: marital status (married); aOR=3.00 (95% CI: 1.15–7.83) and baseline HIV infection (aOR=4.30; 95% CI: 1.83–10.11). Baseline HIV prevalence was 23.3% (95% CI: 18.5 – 28.1) and risk factors were: older age (aOR=2.13; 95% CI: 1.25–5.07), history of STI (aOR=4.21; 95% CI: 2.07–9.34), baseline HPV infection (aOR=2.13; 95% CI: 1.05–4.77), number of lifetime sexual partners (>5) aOR=5.76 (95% CI: 1.41–13.57) and transactional sex (aOR=10.98; 95% CI: 1.86–19.34). Consistent condom use was protective. HIV incidence was 4.2 (95% CI: 1.3–7.1) per 100 person-years (pyr) and being single (aIRR=8.32; 95% CI: 1.27–54.67) was a risk factor while consistent condom use was protective. Baseline HSV-2 prevalence was 56.3% (95% CI: 50.7–62.0) and associated factors were: older age (aOR=1.96; 95% CI: 1.16–2.85), history of STI (aOR=2.12; 95% CI: 1.19–3.91), HIV (aOR=2.22; 95% CI: 1.17–4.22), ever married (aOR=3.80; 95% CI: 1.42–11.90), most recent sexual act with sex worker/casual partner (OR=3.56; 95% CI: 1.49–8.62) and inconsistent condom use (aOR=6.34; 95% CI: 2.24–13.04). HSV-2 incidence was 23.6 (95% CI: 15.4–31.8) /100 pyr and risk factors were: persistent high-risk (HR) HPV (aIRR=3.35; 95% CI: 1.21–11.37), multiple partners (aIRR=4.77; 95% CI: 1.12–11.38) and inconsistent condom use (OR= 3.03; 95% CI: 1.17 – 8.58). Molecular characterization assessment revealed a total of 19 genotypic associations, of which two were negative. HPV-70 was negatively associated with HPV-52 (p=0.018) and HPV-58 (p=0.011). Men infected with multiple HPV genotypes were at increased odds of being detected with a vaccine relevant HPV genotype compared to men with single HPV genotype infection (OR=8.17; 95% CI: 3.77–18.01). T-helper type-1 (Th1) cytokines IFN-γ (5.1-fold; mean fold increase) and IL-2 (4.2-fold) were significantly (p<0.0001) upregulated among men with HPV clearance and not in men with HPV persistence, compared to HPV uninfected men. In the three groups of men, there were no significant changes in Th1 cytokine TNF-α, and Th2 cytokines IL-4, IL-6, IL-10 and IL-13. In conclusion, Fishermen in Kisumu, Kenya had a high burden of HPV, HIV and HSV-2 infections and were at increased risk for incident infection with these three viruses. Key risk factors included: unsafe sex, history of STI, age and marital status. These three viruses were co-factors to each other forming a triad of viral infections. Negative associations between HPV genotypes were rare among fishermen, suggesting lack of HPV genotype competition and potential for type replacement among men. Th1 cytokine response was associated with HPV clearance among these men.