Isolation of a novel orthobunyavirus (Brazoran virus) with a 1.7 kb S segment that encodes a unique nucleocapsid protein possessing two putative functional domains

Abstract

In July, 2012 three isolations were made from mosquitoes collected in Brazoria, Orange and Montgomery counties, Texas, USA. Data from immunofluorescence testing suggested that these isolates are members of the genus Orthobunyavirus. Expanded analyses confirmed that these isolates comprise three independent isolations of the same virus; a novel orthobunyavirus. The genetic organization of the M and L segments of this virus is similar to that of other orthobunyaviruses. However, the S segment (~1.7 kb) is nearly twice the length of known orthobunyavirus S segments, encoding a significantly larger nucleocapsid, N (~50 kDa) and putative non-structural NSs (~20 kDa) proteins in a novel strategy by which the NSs ORF precedes the N ORF. The N protein appears to consist of two functional domains; an amino portion that possesses motifs similar to other orthobunyavirus N proteins and a carboxyl portion that possesses a glutamine-rich domain with no known homologue among Bunyaviridae.

Keywords: Arbovirus; Mosquito; Nucleocapsid; Orthobunyavirus; Phylogeny.