Experimental Infection With Murray Valley Encephalitis Virus. Pigs, Cattle, Sheep, Dogs, Rabbits, Macropods and Chickens

Abstract

Summary A tool of 142 young animals including 10 domestic and 14 feral pigs, 12 Hereford calves, 12 crossbred and 24 Merino lambs, 11 dogs, 8 domestic and 16 feral rabbits, 14 Grey kangaroos, 9 Agile wallabies and 12 chickens was exposed to infection with 4 strains of Murray Valley encephalitis virus (MVE), mainly using orally infected Culex annulirostris mosquitoes. In terms of their viraemic response, the animals were grouped into high (Grey kangaroos, rabbits), moderate (pigs, dogs, chickens) and low (calves, lambs, Agile wallabies). Recipient Cx annulirostris induced to bite these animals 1–7 d post‐inoculation exhibited infection rates up to 95% but usually were much lower. Some animals in which virus was not detected by intracerebral inoculation of suckling mice were capable of infecting up to 5% Cx annulirostris. Haemagglutination‐inhibiting antibody (HI) was of high titre and persistent in rabbits und Grey kangaroos but moderated in others, e.g., cattle, sheep, Agile wallabies to be transient and of low titre. Cattle and Merino lambs were often completely non‐responsive. This study increases the range of vertebrates that could be considered as maintenance or amplifying hosts of MVE and, on the basis of their HI antibody responses, evaluates them as potential sentinels of infection in Australia.

Investigation of neuropathogenesis and control of an equine-pathogenic Australian West Nile virus isolate in an established CD1 Swiss white mouse and a novel rabbit model

“…Rabbits may be a promising alternative model for studying the pathogenesis and immune response to WNV challenge, since previous experimental studies using cottontail rabbits have found a moderate acute viraemia, but with no morbidity or mortality [211]. Similar findings were observed when New Zealand White rabbits (NZWRs) were infected with a closely related flavivirus, MVEV [212]. Other possible alternatives for investigation include guinea pigs and ferrets, which have been used as small animal models for immunologic investigation with JEV [213] and other infectious agents such as influenza [214].…”

“…Interestingly, the viraemia peaks observed in our study were lower than those reported in previous flavivirus infection studies in rabbits (peak ~10 1−3 TCID 50 equivalent or PFU/mL, as compared to ~10 4−5 CID 50 /mL or SMIC LD 50 /mL) [211,212]. This may be explained by the different experimental conditions involved, such as the use of different WNV strains [211], route of inoculation [212], trapping region for CTRs (e.g., Iowa…”

“…[211]), virus isolation methods (CID 50 for [211] and SMIC LD 50 for [212]), and a potentially different adult to weaner ratio in recruited wild rabbit groups. Characterisation of the effects of the mentioned methodological differences is beyond the scope of the current study, but will be an important aspect for future refinement of the rabbit model.…”

Experimental Infection With Murray Valley Encephalitis Virus: Galahs, Sulphur‐crested Cockatoos, Corellas, Black Ducks and Wild Mice

“…No agent was isolated from organs of these mice when inoculated into litters of suckling mice. In order to get enough blood for testing, the mice were sacrificed at 7 d. DISCUSSION This paper on the response of animals to MVE infection complements that of Kay et al (1985). The animal species were selected on the basis of their abundance, distribution, habits and attractiveness to the major vector Cx annulirostris.…”

“…Our data on the persistence of HI antibodies in the 3 psittaciforms and the anseriform species tested are comparable with that of Rufous night herons. Little egrets and with most other animal species tested (Kay et al, 1985). However, it now seems apparent that within any species poor immunological responders do occur.…”