Antibody response to an eight-site intradermal rabies vaccination in patients infected with Human Immunodeficiency Virus

Abstract

Objective To investigate the rabies virus neutralizing antibody response in HIV-1-infected patients with CD4+ cell count ≤200 cells/μL or >200 cells/μL after post-exposure prophylaxis using an eight-site intradermal rabies vaccination regimen. Methods In a prospective cohort study, 27 HIV-1 infected patients were recruited, none of which had a history of rabies vaccination. All patients provided informed consent and were separated into two groups according to their CD4+ cell count (patients with CD4+ counts of ≤200 cells/μL and patients with CD4+ counts of >200 cells/μL). All patients received Purified Chick Embryo Cell rabies Vaccine (PCECV) using a modified eight-site regimen in which 0.1 mL of vaccine was injected intradermally on each of days 0, 3, 7, 14, and 30 (8–8–8–8–8). CD4+ cell counts, HIV-1 viral load and rabies virus neutralizing antibody (RVNAb) concentrations as determined by the Rapid Fluorescent Focus Inhibition Test (RFFIT) were evaluated on blood samples taken on days 0, 3, 7, 14, 30, 90, 180 and 365 after vaccination. Results Of the 27 patients included in the study, 18 patients (67%) had CD4+ cell counts of >200 cells/μL and 9 patients (33%) had CD4+ counts of ≤200 cells/μL. No patients had detectable RVNAb concentrations on day 0. By day 14, all patients had adequate RVNAb concentrations (≥0.5 IU/mL). There was no statistically significant difference in RVNAb concentrations between the two groups on days 3, 7, 14, 30, 90, 180 and 365 after vaccination. Conclusion PCECV is immunogenic in HIV-1-infected patients with CD4+ cell counts below 200 cells/μL when administered in a modified eight-site intradermal PEP regimen.