Pathogenic Differences between Nipah Virus Bangladesh and Malaysia Strains in Primates: Implications for Antibody Therapy

Nipah virus (NiV) is a paramyxovirus that causes severe disease in humans and animals. There are two distinct strains of NiV, Malaysia (NiV M) and Bangladesh (NiV B). Differences in transmission patterns and mortality rates suggest that NiV B may be more pathogenic than NiV M. To investigate pathogenic differences between strains, 4 African green monkeys (AGM) were exposed to NiV M and 4 AGMs were exposed to NiV B. While NiV B was uniformly lethal, only 50% of NiV M -infected animals succumbed to infection. Histopathology of lungs and spleens from NiV B -infected AGMs was significantly more severe than NiV M -infected animals. Importantly, a second study utilizing 11 AGMs showed that the therapeutic window for human monoclonal antibody m102.4, previously shown to rescue AGMs from NiV M infection, was much shorter in NiV B -infected AGMs. Together, these data show that NiV B is more pathogenic in AGMs under identical experimental conditions and suggests that postexposure treatments may need to be NiV strain specific for optimal efficacy.