Objective: Mosquito-borne orthoflaviviruses are maintained in cycles involving mosquito and vertebrate hosts. ZIKV persists in nature in a transmission cycle involving NHPs and also infects humans. Its recent emergence in Brazil has indicated the importance of surveying this virus in Brazilian sylvatic environments. The objective of this study was to investigate the presence of flavivirus in free-living neotropical primates in Southern Brazil and to characterize the detected strains. We present histopathological and molecular evidence that free-ranging Alouatta guariba in Southern Brazil were infected by ZIKV closely related to African lineage MR766 (prototype strain, East African). Methods: Eleven NHPs were RT-PCR positive for ZIKV. High throughput sequencing revealed 99.3% identity to ZIKV MR766, 98.7% identity to ZIKV strain ArD157995 (West African), 89.7% identity to ZIKV P6-740 (Asian strain), and a 216-nucleotide deletion in the NS3 coding region. Isolation attempts resulted in low viral titers, which were insufficient for further experiments. Results: The main lesions in affected NHPs were microcephaly, palatoschisis, calcifications in the neuropil, and discrete inflammatory infiltrates in several tissues. Immunohistochemical analysis indicated viral antigen positivity in one placenta. Conclusion: Repeated detection of an African-lineage ZIKV in the same season over three consecutive years in the Americas in NHPs suggested more than one introduction of ZIKV into the Americas.
Almeida et al. (Thu,) studied this question.