Experimental infection of rhesus macaques with Streptococcus pneumoniae: a possible model for vaccine assessment

Background We explored the possibility of using normal adult rhesus macaques for the preclinical assessment of safety, immunogenicity, and efficacy of newly developed vaccines against Streptococcus pneumoniae infection of the lung. Methods Our primary objective was to determine whether an intra‐bronchial inoculum of at least 106S. pneumoniae colony‐forming units, or one as high as 108–109 organisms, could detectably survive in rhesus macaques for a period longer than 1–2 weeks. If so, we hypothesized, it would be possible to observe signs of pneumonia commonly observed in humans, and discriminate between vaccinated/protected animals and controls. Infection was detectable in bronchoalveolar lavage fluids 3–5 weeks post‐inoculation. Results The clinical course of disease mimicked aspects of that of human pneumococcal pneumonia. Signs of inflammation typical of the disease in humans, such as elevated concentrations of neutrophils and of pro‐inflammatory cytokines in bronchoalveolar lavage fluids were also observed. Conclusions These findings underscore the utility of this model to assess the safety, immunogenicity, and efficacy of newly developed S. pneumoniae vaccines.