Genetic and phenotypic differences between isolates of Murray Valley encephalitis virus in Western Australia, 1972–2003

Abstract

Murray Valley encephalitis virus (MVEV) is a medically important mosquito-borne flavivirus found in Australia and Papua New Guinea (PNG). Partial envelope gene nucleotide sequences of 28 isolates of MVEV from Western Australia (WA) between 1972 and 2003 were aligned and compared phylogenetically with the prototype MVE-1-51 from Victoria in 1951 and isolates from northern Queensland and PNG. Monoclonal antibody-binding patterns were also investigated. Results showed that the majority of isolates of MVEV from widely disparate locations in WA were genetically and phenotypically homogeneous. Furthermore, isolates of MVEV from WA and northern Queensland were almost identical, confirming results from earlier studies. Recent isolates of MVEV from Western Province in PNG were more similar to Australian isolates of MVEV than to isolates from PNG in 1956 and 1966, providing further evidence for the movement of flaviviruses between PNG and Australia. Additional representatives of a unique variant of MVEV (OR156) from Kununurra in the northeast Kimberley region of WA were also detected. This suggests that the OR156 lineage is still intermittently active but may be restricted to a small geographic area in northern WA, possibly due to altered biological characteristics.

Complete Genome Sequences of the Prototype Isolates of Genotypes 2, 3, and 4 of Murray Valley Encephalitis Virus

“…It is enzootic in northern Australia and Papua New Guinea (PNG) and is occasionally epizootic in southeastern Australia (4). Four genotypes (G1 to G4) of MVEV have been recognized (5–8). G1 is the dominant genotype circulating in mainland Australia.…”

“…G1 is the dominant genotype circulating in mainland Australia. Recent isolates from PNG also belong to G1 (6). G2 is a minority genotype and consists of mosquito isolates from the Kimberley region of Western Australia (6).…”

Molecular characterization and phylogenetic analysis ofMurray Valley encephalitis virusandWest Nile virus(Kunjin subtype) from an arbovirus disease outbreak in horses in Victoria, Australia, in 2011

“…36 MVEV is predominantly found in northern Australia and Papua New Guinea but has also been detected farther south when environmental conditions are conducive. 22 The distribution of WNV KUN is broader than MVEV; WNV KUN is enzootic across tropical northern Queensland, the Northern Territory, and Western Australia, and is regularly detected in southeastern Australia. 32 There is considerable anecdotal evidence that, in years where MVEV outbreaks have occurred in human beings, there is also an increased incidence of neurological disease in horses.…”

Influence of Hosts on the Ecology of Arboviral Transmission: Potential Mechanisms Influencing Dengue, Murray Valley Encephalitis, and Ross River Virus in Australia

“…Murray valley encephalitis virus exists in northern Australia, Papua New Guinea, and Indonesia, but is occasionally recorded in southern Australia (Johansen et al 2007, Marshall 1988, Marshall et al 1982c. Culex annulirostris is the major vector in Australia, feeding on a variety of vertebrate species (Kay et al 1985a, van den Hurk et al 2003.…”

“…Research examining the migratory pathways of MVEV hosts is needed to provide further support to dispersal hypotheses. Molecular evidence indicates Australian MVEV reflects frequent circulation from a constrained enzootic focus in northern Australia and is not known to result from human dispersal (Johansen et al 2007, Lobigs et al 1986, Mackenzie et al 1996.…”