Abstract
BackgroundSchistosoma mansoni is one of the most common helminth infections affecting a large population of people in sub-Saharan Africa. This helminth infection is known to cause immunomodulation which has affected the efficacy of a number of vaccines. This study examined whether a chronic schistosoma infection has an effect on the immunogenicity of HPV vaccine which is currently administered to girls and women aged 9 to 24. Little is known about the immune responses of the HPV vaccine in individuals with chronic schistosomiasis.MethodsThis study was carried out at the Institute of Primate Research (IPR) and involved an Olive baboon model. The experimental animals were randomly placed into three groups (n = 3–4); Two groups were infected with S. mansoni cercaria, and allowed to reach chronic stage (week 12 onwards), at week 13 and 14 post-infection, one group was treated with 80mg/kg of praziquantel (PZQ). Sixty four weeks post schistosoma infection, all groups received 2 doses of the Cervarix HPV vaccine a month apart. Specific immune responses to the HPV and parasite specific antigens were evaluated.ResultsAnimals with chronic S. mansoni infection elicited significantly reduced levels of HPV specific IgG antibodies 8 weeks after vaccination compared the PZQ treated and uninfected groups. There was no significant difference in cellular proliferation nor IL-4 and IFN-γ production in all groups.ConclusionChronic S. mansoni infection results in reduction of protective HPV specific IgG antibodies in a Nonhuman Primate model, suggesting a compromised effect of the vaccine. Treatment of schistosomiasis infection with PZQ prior to HPV vaccination, however, reversed this effect supporting anti-helminthic treatment before vaccination.
Highlights
Human Papillomavirus (HPV) remains one of the most common sexually transmitted viruses in the world and is responsible for cervical cancer
This study examined whether a chronic schistosoma infection has an effect on the immunogenicity of HPV vaccine which is currently administered to girls and women aged 9 to 24
Chronic S. mansoni infection results in reduction of protective HPV specific IgG antibodies in a Nonhuman Primate model, suggesting a compromised effect of the vaccine
Summary
Human Papillomavirus (HPV) remains one of the most common sexually transmitted viruses in the world and is responsible for cervical cancer. Three licensed vaccines against HPV are available; the quadrivalent vaccine Gardasil which provides protection against HPV 6,11,16, 18, bivalent vaccine Cervarix which confers protection against the 2 variants, HPV 16 and HPV 18 [7] and a nanovalent vaccine Gardasil which protects against HPV 16, 18, 31, 33, 45, 52 and 58 subtypes [8,9] These vaccines contain virus-like-particles (VLPs) consisting of the L1 capsid protein. These proteins are highly immunogenic resulting in high levels of serum antibody immune responses once injected intramuscularly [10]. This helminth infection is known to cause immunomodulation which has affected the efficacy of a number of vaccines. Little is known about the immune responses of the HPV vaccine in individuals with chronic schistosomiasis
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