Characterisation of divergent flavivirus NS3 and NS5 protein sequences detected in Rhipicephalus microplus ticks from Brazil

Abstract

Transcripts similar to those that encode the nonstructural (NS) proteins NS3 and NS5 from flaviviruses were found in a salivary gland (SG) complementary DNA (cDNA) library from the cattle tick Rhipicephalus microplus. Tick extracts were cultured with cells to enable the isolation of viruses capable of replicating in cultured invertebrate and vertebrate cells. Deep sequencing of the viral RNA isolated from culture supernatants provided the complete coding sequences for the NS3 and NS5 proteins and their molecular characterisation confirmed similarity with the NS3 and NS5 sequences from other flaviviruses. Despite this similarity, phylogenetic analyses revealed that this potentially novel virus may be a highly divergent member of the genus Flavivirus. Interestingly, we detected the divergent NS3 and NS5 sequences in ticks collected from several dairy farms widely distributed throughout three regions of Brazil. This is the first report of flavivirus-like transcripts in R. microplus ticks. This novel virus is a potential arbovirus because it replicated in arthropod and mammalian cells; furthermore, it was detected in a cDNA library from tick SGs and therefore may be present in tick saliva. It is important to determine whether and by what means this potential virus is transmissible and to monitor the virus as a potential emerging tick-borne zoonotic pathogen.

A Multicomponent Animal Virus Isolated from Mosquitoes

“…A draft genome (Ladner et al, 2014) was obtained with 70.6% to 98.1% coverage for each of the four genome segments that have been described for JMTV (Shi et al, 2015). RC27 exhibited high similarity to isolates from ticks: 88–92.6% nt identity across all four segments compared to SY84 from China (Qin et al, 2014) and MGTV from Brazil (Maruyama et al, 2014). In species-level phylogenetic analyses, the Chinese isolates (Qin et al, 2014) formed a distinct clade compared to the isolates from Uganda and Brazil (Figure S6).…”

“…These viruses have tentatively been coined Jingmenviruses (Shi et al, 2015). JMTV and Mogiana tick virus (MGTV) are two highly similar (88–90% identical, nt-level), segmented viruses that have been isolated from cattle ticks ( Rhipicephalus microplus ) in China (Qin et al, 2014) and Brazil (Maruyama et al, 2014), respectively. Here we report an additional virus with high similarity to JMTV, which we detected in the blood of a non-human primate in Uganda.…”

“…Although MGTV was not initially recognized as being segmented, we used the published Illumina dataset [SRR525284 (Maruyama et al, 2014)] to assemble nearly full length contigs with sequence homology to all four segments of JMTV (see Supplemental Experimental Procedures). Similarly, while Webster et al (2015) only reported one segment (encoding the putative RdRp) for the three Jingmenviruses they sequenced, we identified several additional contigs in their dataset with significant sequence homology to segments 1–4 from GCXV (see Supplemental Experimental Procedures).…”

Nhumirim virus, a novel flavivirus isolated from mosquitoes from the Pantanal, Brazil

“…In 1997, a flavivirus was isolated from Amblyomma cajennense specimens collected from a morbid capybara in the state of São Paulo, Southeast Brazil, but this virus has not been characterized further [32]. In 2006, a potential novel flavivirus was isolated from Rhipicephalus microplus collected in dairy cattle, also from São Paulo [10]. …”

“…Outbreaks caused by other flaviviruses, including Rocio virus (ROCV), as well as isolated human cases of infection with Saint Louis encephalitis virus (SLEV), Cacipacore virus (CPCV) and Ilheus virus (ILHV) have also been reported in the country [4–7]. Flaviviruses of eleven species have been isolated in Brazil, including Naranjal-like virus from a marsupial, Culex flavivirus from Culex mosquitoes, and a potential novel flavivirus recently isolated from ticks [8–10]. In 2011, West Nile virus (WNV) was reported in Brazil for the first time based solely on serological evidence in healthy horses sampled in 2009 and 2010 in the Pantanal wetland region of west-central Brazil [11].…”