1.A.100 The Rhabdoviridae Putative Viroporin, U5 (RV-U5) Family
Viruses belonging to the family Rhabdoviridae infect a variety of different hosts including insects, vertebrates and plants. There are over 200 rhabdoviruses isolated around the world. The complete genome sequence and predicted transcription strategy of Wongabel virus (WONV), a rhabdovirus isolated from biting midges (Culicoides austropalpalis) is available. The 13,196 nucleotide genome encodes five typical rhabdovirus genes N, P, M, G and L, plus three genes located between the P and M genes (U1, U2, U3) and two overlapping the N and G genes (U4, U5). The U5 gene product has characteristics typical of viroporins with structural similarities with the alpha-1 protein (putative viroporin) of viruses in the genus Ephemerovirus, and similarity with the avian-associated Flanders virus has been noted (Gubala et al. 2008).
Viroporins are viral ion channel proteins usually with 50-120 amino acids. They play important roles in regulating virus replication, including virus entry, assembly and release. They may also modulate the electrochemical balance in subcellular compartments of the host cells. Wang et al. 2011 summarized advances concerning viroporins, including PBCV-1 KcV, influenza M2, HIV-1 Vpu, HCV p7, picornavirus 2B, and the coronavirus E and 3a viroporins with emphasis on their functions and mechanisms.