Genomic and phylogenetic characterization of Merino Walk virus, a novel arenavirus isolated in South Africa

Abstract

Merino Walk virus (MWV), a proposed novel tentative species of the family Arenaviridae, was isolated from a rodent, Myotomys unisulcatus, collected at Merino Walk, Eastern Cape, South Africa, in 1985. Full-length genomic sequence confirmed MWV as an arenavirus related distantly to Mobala, Mopeia and Ippy viruses, all members of the Old World arenavirus complex. We propose MWV as a tentative novel species in the Lassa-lymphocytic choriomeningitis virus complex, based on its isolation from a novel rodent species and its genetic and serological characteristics.

Fig. 1.

MWV as observed at the plasma membrane of an infected Vero cell in an ultrathin section. Bar, 100 nm.

Fig. 2.

Phylogenetic analyses of MWV were inferred based on primary nucleotide alignments of (a) GPC and (b) L sequences. Maximum clade credibility trees generated from analysis of arenavirus GPC or L sequences are shown. Posterior probabilities are listed below the branches for supported nodes.

Fig. 3.

Phylogenetic analysis of MWV based on secondary structure alignments of G1 sequences. Receptors reported to interact with the G1 glycoprotein moiety are shown, where • represents NW arenaviruses using TfR1, ▪ represents viruses using host TfR1, but not human receptors, and ○ indicates OW and clade C NW arenaviruses that use α-DG.

Fig. 4.

Predicted secondary structures of the (a) S and (b) L segments. The S segment (a) is predicted to form a single, highly stable stem–loop structure, whereas the L segment (b) is assumed to form a complex folding structure.

Fig. 5.

Known geographical distribution of arenaviruses in Africa based on isolation. MOBV, MOPV and IPPYV, which have not been associated with disease in humans, are shown by ⧫. LASV (⧫) and LUJV (◊) are associated with haemorrhagic fever. The arrow indicates the approximate location where MWV was recovered (•).