An investigation into the role of chronic Schistosoma mansoni infection on Human Papillomavirus (HPV) vaccine induced protective responses

Abstract

Background Schistosoma 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. Methods This 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. Results Animals 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.

Schistosoma mansoni infection induces plasmablast and plasma cell death in the bone marrow and accelerates the decline of host vaccine responses

“…Indeed, PZQ has also been shown to improve mice immune responses to the HIV vaccines [35,43] and the hepatitis B virus vaccine [37]. In Olive baboons, PZQ treatment in the chronic stage of S. mansoni infection significantly reversed S. mansoni associated reductions of HPV specific IgG antibodies [36]. Together, our present findings point at a beneficial effect of PZQ on vaccine responses in schistosomiasis-diseased animals and children.…”

“…´rin (BCG) vaccine [34] and HIV specific vaccines [35]. In another study, an association between S. mansoni infection and reductions of serologic IgG antibodies mounted by the Human Papillomavirus vaccine in non-human primates was described [36]. Highlighting the immunosuppressive nature of different Schistosoma spp.…”

Effects of schistosomes on host anti-viral immune response and the acquisition, virulence, and prevention of viral infections: A systematic review

“…Two studies have investigated the effect of schistosome infection on HPV vaccination. A small number of S. mansoni-infected baboons had lower HPV IgG antibody titers than baboons without schistosome infection, though praziquantel treatment prior to vaccination eliminated these differences [121]. However, a large study reported no difference in anti-HPV antibody titers seven and 12 months after HPV vaccination in 298 girls and women aged 10-25 with versus without S. mansoni infection [122].…”

Elucidation of Cellular Responses in Non-human Primates With Chronic Schistosomiasis Followed by Praziquantel Treatment

“…It is wellestablished that helminths modulate the immune response, but little is known about how this modulation affects vaccine efficacy. Evidence suggests that chronic helminth infections during vaccine administration might impair the protective immunity elicited by the vaccine (Gent et al, 2019), especially schistosomiasis which can impair the long-term response to certain vaccines that require predominant Th1 responses (Riner et al, 2016;Wajja et al, 2017). Likewise, PZQ treatment has been shown to alter the polarization of schistosome-specific cytokine responses and could potentially contribute to the development of resistance to reinfection (Bourke et al, 2013).…”