Detection of Zika virus RNA and neutralizing antibodies in neotropical primates during the epidemic period for the disease in Brazil

Abstract

Purpose: Zika virus (ZIKV) is a mosquito-borne viral disease associated with fetal microcephaly and other central nervous system (CNS) symptomatology. It was first identified in a Rhesus macaque in Uganda and later in humans (Zika fever), in 2015 ZIKV was notified in Northeast Brazil related to CNS alterations and rapid spread. Considering that old-world primates are susceptible to ZIKV, samples from neotropical primates from Ceara state, Northeast of Brazil, were preliminary tested and found to be positive for ZIKV by qPCR. The aim of this study was to extend the sampling of primates by revisiting the localities with positive animals and to study the presence of immune response to the virus. Methods & Materials: A total of 132 samples from six species of neotropical primates captured from June 2015 to December 2016 was tested, out of these, nine (six marmosets – Callithrix jacchus – and 03 capuchin monkeys – Sapajus libidinosus) were positive by quantitative RT-PCR assay. The genetic sequences showed high similarity with the strains circulating in Brazil. Neutralizing antibodies for ZIKV were detected by PRNT in two samples (PRNT50 = 73,7 and 13,2). Results: All the positive samples were obtained from peridomestic animals captured in proximity to humans and captured between the June of 2015 and February of 2016, from March to December of 2016 there were no positive samples. The temporal detection of ZIKV in the primates is in agreement with the reports and confirmations of congenital syndrome related to ZIKV in Ceara, where the majority of reports occurred from November/2015 to March/2016 with significant decrease after this period. The two animals that had neutralizing antibodies for ZIKV as indicated by PRNT were in direct or close contact with animals positive for qRT-PCR and these antibodies may constitute additional evidence for virus circulation. Conclusion: These results demonstrate the occurrence of natural ZIKV infection in neotropical primates and the temporal detection suggests that virus detection in animals accompanied the epidemic period in humans. However since some positive animals were free raging, a continuous surveillance is necessary to exclude the possibility of virus circulation and transmission in wild environments.