Antibody responses to rabbit haemorrhagic disease virus in predators, scavengers, and hares in New Zealand during epidemics in sympatric rabbit populations.
OBJECTIVE
To test for antibodies to rabbit haemorrhagic disease (RHD) virus (RHDV) in sera from mammals and birds associated with rabbit populations infected with RHDV.


METHODS
Sera from feral and domestic cats, feral ferrets, stoats, hedgehogs, hares, harrier hawks, and black-backed gulls were taken (apart from some of the hares) from areas in New Zealand where RHD was active among rabbit populations. The presence of antibodies to RHD was investigated using a competition enzyme-linked immunosorbent assay (ELISA).


RESULTS
Some individual animals of all species were seropositive. Thirty eight of 71 feral cats, but only 1/80 domestic cats were seropositive at a 1:40 dilution. The latter had not been exposed to RHDV. Also reactive in the ELISA were 2/8 stoats; 11/115 ferrets, with significantly more females having antibodies than males; 4/73 hedgehogs; 2/18 hawks, and 1/30 gulls. Three of 66 hares, comprising 3/14 from one population, were seropositive.


CONCLUSIONS
Apart from the hares, all these species are known to prey upon rabbits or scavenge their carcasses, a possible means of exposure to RHDV. The possibility that the positive test reactions were due to cross-reactions with other caliciviruses cannot be ruled out, especially for the hares. Nor could the study differentiate whether the positive results were due to an antigenic reaction to ingestion of RHDV, as suggested by overseas work, or to infection of new species by RHDV. These possibilities are being investigated further.
Parkes
J P
JP
Landcare Research, PO Box 69, Lincoln 8152, New Zealand. parkesj@landcareresearch.co.nz
Heyward
R P
RP
Henning
J
J
Motha
M X J
MX