Establishment of a rhesus macaque model for coxsackievirus A6 infection: Pilot study to evaluate infection initiated through the respiratory or digestive track.

Coxsackievirus A6 (CVA6) is a primary pathogen associated with hand, foot, and mouth disease (HFMD) and is typified by fever, rashes or herpetic lesions at distinct locations. Although HFMD patients exhibit mild symptoms, a subset of patients may develop severe complications, such as viral encephalitis, myocarditis, pneumonia, and neurological disorders. However, in addition to rodent models, such as the CVA6-infected mouse model, no definitive nonhuman primate animal model or related research or analysis tool is available, which makes the development of suitable nonhuman primate animal models particularly crucial. In this study, 3- to 4-month-old rhesus monkeys were infected via the respiratory or digestive tract, and the pathogenic, pathological, and immunological alterations following CVA6 infection were investigated. The results revealed that the infected rhesus monkeys exhibited symptoms similar to those of patients, including signs of HFMD, blood cell changes, viremia, viral excretion, and inflammatory reactions during the acute phase (1-11 days). Pathological observations revealed inflammatory reactions in the intestinal and lymph node tissues. Notably, the acute symptoms gradually waned in the recovery phase (12-120 days), and a high level of neutralizing antibodies was sustained. Intriguingly, no significant disparity was observed between the infections initiated via the respiratory or digestive tract in terms of clinical symptoms, hemogram results or virus shedding. Overall, this study yielded a comprehensive dataset regarding the physiological, pathological, and immunological outcomes of CVA6 infection in a primate host, enhancing our comprehension of the mechanism of CVA6 infection and providing essential data for related vaccine and drug development.