Human Papillomavirus Vaccine immune responses in an Olive baboon model is not compromised by chronic Schistosoma mansoni infections.

Human papillomavirus (HPV) vaccines elicit specific serum antibodies that confer long-lasting protection and may reduce HPV-related cancers. However, helminthic infections such as chronic schistosomiasis infection at the time of HPV vaccination are known to alter immune responses. This study investigated the impact of chronic S. mansoni infection on immune responses to the HPV vaccine in olive baboons. Baboons were assigned to three groups: (1) untreated S. mansoni-infected, (2) S. mansoni-infected and treated with Praziquantel, and (3) uninfected controls. All received two doses of the Cervarix HPV vaccine four weeks apart. Immune responses were measured using flow cytometry and ELISA. Gardasil® quadrivalent HPV vaccine antigen was used in both ELISA and PBMC stimulation for cytokine ELISA supernatants. HPV-specific whole IgG levels significantly increased in all groups except for the untreated S. mansoni-infected group, whose increase was significant after the second dose. Similarly, IgG1 levels increased only after the second dose. There was no significant difference between the treated and untreated infected groups. These findings emphasize the importance of a booster dose for strong antibody production and suggest that a delayed HPV-specific whole IgG response in untreated S. mansoni-infected individuals reinforces the need for booster HPV vaccination in endemic regions. The results affirm the vaccine's effectiveness in S. mansoni endemic areas.