Isolation of Murray Valley Encephalitis Virus and Other Arboviruses in the Ord River Valley 1972–1976

Abstract

Summary This paper summarizes the isolation of arboviruses from mosquitoes collected in the Ord Valley between 1972 and 1976. A total of one hundred and ninety five strains of at least fifteen antigenically distinct viruses have been isolated. Seven of these isolates appear to be ‘new’ antigenic types, and several are undergoing further testing. These are three new rhabdoviruses (Kununurra [OR194], a virus provisionally named Kimberley [OR250] and OR189 [provisionally named Parry's Creek]), three ungrouped, non‐haemagglutinating viruses (OR379, OR512, OR869) and a virus (OR540) which reacts to Poly Anopheles A world grouping fluid. The remaining viruses have been previously identified in Australia. These include Murray Valley encephalitis (MVE), Kunjin, Kokobera, Sindbis, Koongol, Wongal, Wongorr and a virus in the Corriparta serological group. The most important finding of these studies is that MVE displays an annually recurrent pattern of activity with a peak seasonal transmission rate at the end of the wet monsoon. This is the first definition of a probable endemic focus of MVE activity in Australia. The major vector for the majority of the viruses isolated was, by inference, Culex annulirostris. However, Aedeomyia catasticta was implicated as a major vector of the Corriparta group virus.

A Preliminary Investigation of the Ecology of Arboviruses in the Derby Area of the Kimberley Region, Western Australia

“…Serological studies (Stanley and Choo, 1961; showed wide-Spread prevalence of neutralizing antibodies among residents throughout the Kimberley, and studies in the Ord Valley have defined a recurrent annual pattern of MVE transmission (Liehne et al. 1976a;Liehne et al, 1981). The isolation of a further four strains of MVE from Derby in this study augments this data and adds to the evidence for MVE being endemic throughout the Kimberley region.…”

“…The predominance of viruses of the Koongol group among the isolates (7 of 13) is very similar to results from the Ord (Liehne et al, 1981). These Koongol group viruses consisted of two strains of Wongal and five nonhaemagglutinaling strains which have yet to be fully characterized (Liehne et al, 1981).…”

“…These isolations form a viral flora which, although reduced slightly in diversity, closely matches the defined virus flora in the Ord Valley (Liehne et al, 1981). This relationship is examined in Table 4.…”

“…These Koongol group viruses consisted of two strains of Wongal and five nonhaemagglutinaling strains which have yet to be fully characterized (Liehne et al, 1981). The remaining virus was a single strain of a virus (WK60) which reacted with polyvalent world grouping sera for the Anopheles A and B groups.…”

“…isolation of virus and characterization of isolates during the Ord River arbovirus programme were maintained in this study (Liehne et al, 1976a;Liehne et al, 1981). All mosquito pools and subsequent isolates were given a WK.…”