taminating a trial batch of attenuated Marek’s Disease vaccine was submitted for identification by Mr Choi Chung, University of Sydney Veterinary School, Camden, as coverslip preparations following 5 passages in C E F cultures and 1 passage in duck embryonic fibroblast cultures. This virus has also been identified by the IFA test and designated as REV/NSW/1/77. A reference chicken serum containing antibodies to REV was kindly supplied to this laboratory by Dr R. L. Witter, and has been used in the IFA test to compare the antigenic relationship of strains of REV isolated in Australia and the U.S.A. Staining with the reference serum produced moderate fluorescence to a dilution of 11640 in coverslips of CEF cells infected with either REV@/ 1/73 or REV/VIC/ 1/76, corresponding exactly to the homologous IFA titre given for this serum with American strains of REV (R. L. Witter, personal communication). Work is in progress with REV/NSW/ 1/77 and this reference serum. Antibody to REV has recently been detected in unvaccinated Australian poultry flocks and in serums from the pwlt- - flock from which the substrates for contaminatecl avian vaccines were derived (R. L. Witter, personal communication through P. T. Gilchrist). Also, a retrospective survey of 586 commercial poultry serums collected during 1973 to 1975, prior to the use of avian vaccines known to be contaminated with REV, has been made for REV infection using the IFA test

at this laboratory. Antibody to REV was detected in 2 of 14 breeder-layer flocks examined in New South Wales, and 1 of 30 broiler flocks as well as a closed flock of turkeys in Queensland. It is therefore evident that REV occurs as a natural infection of Australian poultry flocks. We are studying the epizootiology of REV in Australian poultry, but these investigations are complicated by the recent widespread use of avian vaccines accidentally contaminated with REV. The possible danger of contamination by REV of avian vaccines in Australia was predicted by Grimes and Purchase (1973) and it is now apparent that poultry flocks intended for production of avian vaccines must be known to be free of infection by this virus. T. J. BAGUST, D. P. DENNETT, CSIRO Division of Animal Health, Animal Health Research Laboratory, Private Bag No. I , P.O., Parkville, Victoria, 3052 16 August 1977 References Grimes, T. M. and Purchase, H. G. (1973)-Aust. vet. J. 49: 466. Koyama, H., Suzuki, Y., Ohwada, Y. and Saito, Y. Dis. 2 0 429. (1976)-Avian Purchase, H. G. and Witter, R. L. ( 1 9 7 5 t C u r r . Top. Microbiol. Immunol. 71: 103.

ISOLATION OF LEPTOSPIRA INTERROGANS, SEROTYPE BA LCANlCA FROM A BRUSH-TAILED OPOSSUM (TRICHOSURUS VULPECULA) We would like to report the isolation of Leptospira interrogans, serogroup Hebdomadis, serotype balcanica, from a brush-tailed opossum (Trichosurus vulpecula) in Victoria. L. balcanica has been isolated from cattle and swine in the USSR (Semenova et a1 1965) and from brushtailed opossums in New Zealand (S. Hathaway, personal communication). We believe that this is the first report of this serotype from Australia. The isolate was obtained from a healthy mature male opossum trapped in a rural environment 40 km north west of Melbourne, Victoria. The opossum had a micro-agglutination (MA) antibody titre of 128 against L. hardjo antigen. The opossum was given hydrocortisone acetate intramuscularly at the rate of 1 mg/kg on 11 occasions over a 16day period before euthanasia. Darkfield examination of urine sediment during the 14-day period revealed leptospira-like structures on 2 occasions. The opossum was killed and portions of both kidneys were homogenised in sterile buffered saline in a glass tissue grinder and 1 ml of the resulting suspension was inoculated intraperitoneally into each of 2 weanling guinea pigs. Blood samples were collected by cardiac puncture from each guinea pig daily for 5 days and inoculated into EMJH leptospira media*. On post-mortem examination the opossum was found to be in good body condition with no gross lesions evident. A few scattered foci of chronic interstitial nephritis were seen on histologic examination of the kidneys. The isolate was identified as L. balcanica by the Regional FAO/WHO Leptospirosis Laboratory, BrisDifco Laboratories. Detroit, Michigan

508

bane, Queensland. Absorption tests performed at this same laboratory with a recent isolate of L. balcanica from a New Zealand opossum indicated both strains to be identical (N. D. Stallman, personal communication 1977). We had found many opossums in the area in which this opossum was trapped with positive MA titres to L. hardjo and were attempting to demonstrate L. hardjo in these animals. However, as both L. hardjo and L. balcanica are members of the Hebdomadis serogroup, antibodies against them almost completely cross-react in the MA test. Thus, opossums with positive serologic titres to L. kardjo antigen could be infected with L . hardjo, L. balcanica, or some other number of the Hebdomadis serogroup. Serologic evidence accumulated by us suggests that Hebdomadis infection in opossums is widespread in Victoria. Whether or not L. balcanica also infects cattle in Victoria is unknown at present. However, if it does, and is as non-pathogenic for that species as it appears to be for opossums, it may well explain some of the inconsistencies associated with bovine “ L . hardjo infection” in this area. P. T. DURFEE, P. J. A. PRESIDENTE. University of Melbourne, Department of Veterinary Paraclinical Sciences, Veterinary Clinical Centre, Werribee, Victoria, 3030 25 July 1977 Reference Semenova, L. P., Soloshenko, I. 2. and Anan’in, V. V. ( 1 9 6 5 b Z h . Mikrobiol. Epidem. Immunobiol. 4k 61. Australian Veterinary Journal, Vol. 53, October, 1977