Research Note EFFECT OF LEVAMISOLE ON THE COURSE OF MALIGNANT CATARRHAL FEVER VIRUS INFECTION IN RABBITS E. Z. MUSHI1, F . R. RURANGIRWA1 a n d L. KARSTAD2
x Veterinary Research Department, Kenya Agricultural Research Institute, PO Box 32, Kikuyu, Kenya; s Veterinary Research Laboratories, PC) Kabete, Kenya
The herpesvirus of malignant catarrhal fever (MCF) produces a highly fatal lympho-proliferative disease in cattle and rabbits. The immune mechanism of MCF virus infected rabbits is probably compromised because these rabbits do not recover. We report on the effect of levamisole, a potent anthelmintic which restores T-cell function in compromised hosts on the course of MCF virus infection in rabbits. MCF virus infected rabbits were inoculated subcutaneously with levamisole (NilvermS). Four rabbits were inoculated on alternate days from day 7 post-infection; 2 rabbits received 10 mg/kg and the rest 50 mg/kg. Another 4 rabbits were inoculated daily from the 1st day of pyrexia (>40°C). Serum was obtained twice a week and tested for virus neutralising antibodies in microtitre plates (Mushi and Plowright, 1979). Total white blood cell counts were carried out twice a week. Levamisole did not alter the course of MCF virus infection of 8 rabbits inoculated with the drug. The terminal blood leucocyte changes were the same as those described by Plowright (1953) and no particular change could be attributed to the levamisole inoculation. Virus neutralising antibodies were first detected a few days before the onset of pyrexia and persisted until death and levamisole treatment did not influence the time of appearance of virus neutralising antibodies. Recently Weisner (1979) reported successful treatment of MCF in the gaur (Bos fiontalis gaurus) prophylactically inoculated with levamisole. The causes for the different responses to levamisole inoculation in MCF infected gaur or rabbits may be manifold: differences in the 2 types of MCF under consideration--the gaur most likely were infected with sheep-associated MCF whilst the rabbits were infected with wildebeest-derived MCF virus; timing of the treatment has also been shown to play a role; species of animals involved; and perhaps levamisole has no effect on the course of wildebeest-derived MCF virus infection in rabbits. ACKNOWLEDGEMENTS
This paper is published with the permission of the Director, Veterinary Research Department, Muguga. Dr L. Karstad was supported by the Canadian International Development Research Centre. Accepted for publication March 1980 REFERENCES
Mvsm, E. Z. & Ih.OWRIGHT,W. (1979). Research in Veterinary Science, 27, 230-232. PLOWmOHT, W. (1953). Journal of Comparative Pathology, 63, 318-334. W]~[SN~, H. (1979). Veterinary Bulletin, 49, 584.