Influenza A Infection

Infection with the influenza A virus is very common in humans. Influenza A viruses undergo frequent changes in antigenic determinants (shifts and drifts) causing regular global epidemics in humans. Experimental infection of chimpanzees with human influenza isolates has been successful in a few trials; however, the chimpanzees remained relatively asymptomatic and it took a high concentration of viral inoculums delivered directly to the lung bronchii to establish infection. Many facilities with captive great apes work under the assumption that their human caretakers can infect the apes with human influenza A. However, no natural infection with influenza A has been documented in a captive or wild ape by antibody screening and viral isolation. One possible explanation is that the sialic acid target for human influenza in the upper airways (alpha2-6-linked sialic acid) in not present in the chimpanzee airway cells. As for the limited symptomatic response to experimental infection, this could be due to the more limited T cell reactivity to the infection.