Europ. J. Cancer Vol. 12, pp. 433--439. Pergamon Press 1976. Printed in Great Britain Diagnostic Tests of Bovine Leukemia Comparison between an Hematological Test the Serological Diagnosis* and M. MAMMERICKX?~, D. PORTETELLE$§, R. KETTMANN$¶, J. GHYSDAEL$]], A. BURNY+ + and D. DEKEGEL# ~D~partement de Virologic, Institut National de Recherche Vgt~rinaire, 99 Groeselenberg, 1180 Bruxelles, Belgium $Facultd d'Agronomie, 5800 Gembloux, Belgium, and Dgpartement de Biologic Mole'culaire, Universitd Libre de Bruxelles, 67 rue des Chevaux, 1640 Rhode-Saint-Gen~se, Belgium # Laboratoire de Microscopic Electronique, Institut Pasteur du Brabant, 22 rue du Remorqueur, 1140 BruxeUes, Belgium Abstract--The classical hematological test (lymphocytes counts) was applied to 5 herds of cattle where the enzootic form of bovine leukemia was diagnosed. In the same five herds, a search for antibodies directed against bovine leukemia virus (BLV) p 24 was carried out using an agar gel immunodiffusion (AGID) technique. Among the 245 animals screened, 30 reacted positively to both tests, 11 were positive by hematological test only and 15 were positive by serological test only. From these results we would advise to eliminate from so heavily infected herds, all the animals showing abnormal blood pictures and all these reacting positively to the immunological test. INTRODUCTION ENZOOTIC bovine leukemia is a lympho- proliferative disease. Epidemiological and ex- perimental observations lead many investi- gators to consider a virus (or viruses) as prob- able etiological agent(s) of the disease. A major progress towards identification of a viral agent was the observation [1] that leukemic lymphocytes kept in survival cultures release "C-type" particles. This observation was rapidly confirmed by several groups [2-4]. These particles, now called bovine leukemia virus (BLV) contain a high molecular weight RNA-reverse transcriptase complex. 3H-C DNA synthesized in vitro in the disrupted Accepted 16January 1976. *Part of this work was supported by a Research contract with the Caisse G~n6rale d'Epargne et de Retraite (Fonds Canc6rologique). §Assistant of the "Fonds Canc6rologique de la Caisse G6nSrale d'Epargne et de Retraite", Belgium. ¶Aspirant of the "Fonds National de la Recherche Scientifique", Belgium. []Fellow of the "Institut pour l'Encouragement de la Recherche Seientifique darts l'Industrie et l'Agri- culture", Belgium. particles hybridizes only to a very limited extent to normal bovine DNA, but anneals to a maximum extent to bovine tumor DNA [5]. These biochemical results also point to enzootic bovine leukemia being an infectious disease caused by a viral agent, BLV. If this is so, one expects the infected animal to rise antibodies against BLV or some BLV components. It is now known that leukemic animals carry antibodies directed against an ether sensitive antigen and an ether resistant antigen both present in homogenates of cul- tured leukemic lymphocytes [6]. In the present study we screened animals of five herds (total = 245 animals) for the presence of antibodies directed against the ether resistant antigen, a viral protein with a molecular weight: 24.000. The results obtained by the agar gel immuno- diffusion test (AGID test) were compared to these provided by hematological examination of all the animals. Hematological tests, inter- preted here according to the key of G6ttingen, detect cases of persistent lymphocytosis. It might be useful to notice here that persistent lymphocytosis, whilst frequently considered as a pretumoral situation is not necessarily the rule [7, 8]. In that respect, recent results from 433