Bovine Leukaemia‐virus Infection in Costa Rica

Abstract

Summary The geographical distribution of bovine leukaemia‐virus (BLV)‐infected herds in Costa Rica and the isolation of BLV from cases of enzootic bovine leukosis are presented. It was found that BLV is prevalent throughout the country, affecting mostly dairy cattle (Bos taurus) located in the highlands around the central valley of Costa Rica. By contrast, beef cattle (Bos indicus) raised in the lowlands were affected to a lesser extent. One out of four isolates of BLV obtained from local cattle with lymphosarcomatous tumours was analysed and had similar physical, serological and biological characteristics to a reference strain of BLV isolated in the USA. However, different patterns of recognition of BLV‐protein p24 were observed among naturally infected cattle using the western‐blotting technique.

An Outbreak of Enzootic Bovine Leukosis in Upper Egypt: Clinical, Laboratory and Molecular–Epidemiological Studies

“…The total prevalence found in the herd agrees with that at reported by Jimenez et al. (1995) who recorded a total prevalence of 51%, when they tested 1876 herds in Costa Rica and found high prevalences in Holstein and Jersey breeds (65.7%).…”

A region on bovine chromosome 15 influences beef longissimus tenderness in steers.

“…Development of interspecies composites exhibiting desirable characteristics of Bos indicus and Bos taurus cattle without undesirable attributes could be accelerated using marker-assisted selection. Advantages of Bos indicus germplasm relative to Bos taurus are greater heat tolerance (Carvalho et al, 1995;Hammond et al, 1996), greater resistance to parasites (Fourie and Kok, 1995;Bock et al, 1997) and viral infections (Jimenez et al, 1995;Soeharsono et al, 1995), and improved maternal calving ease (Olson et al, 1993). Bos indicus × Bos taurus crosses express greater heterosis effects for direct and maternal traits (Peacock et al, 1982) and neonatal survival (Peacock and Koger, 1980) than do crosses within species.…”

Lymphoproliferation Assays in Cattle Naturally Infected with Bovine Leukaemia Virus (BLV) and Bovine Immunodeficiency-Like Virus (BIV)

“…Dual infections are frequent in dairy herds of the central valley in Costa Rica (HIDALGO et al, 1995) and elsewhere (AMBORSKY et al, 1989;MARTIN et al, 1991;COCKERELL et al, 1992), and single-infected animals are difficult to find. BLV infections in Costa Rica have been studied for many years (RODRIGUEZ and ALVARADO, 1980;DUCREAUX et al, 1987;MORENO et al, 1992;JIMENEZ et al, 1995), and there is now a clear picture of the virus distribution. For BIV more studies are needed (HIDALGO et al, 1995).…”

“…Cattle A sample of 30 animals (Holstein, 4 to 6 years) were selected from five different dairy farms of the central valley of Costa Rica, where infectivity for BLV has been shown to be above 30 % (MORENO et al, 1992;JIMENEZ et al, 1995), 18 animals were BLV-positive by ELISA, 12 seronegative cows from two farms where BLV eradication programmes were in progress, were used as controls. All animals were seronegative for bovine viral diarrhoea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV), screened by serum neutralization.…”

“…Because the cattle industry is one of the main sources of income in Costa Rica, BLV infections have been studied for more than 10 years (RODRIGUEZ and ALVARADO, 1980; DUCREAUX et a]., 1987; MORENO et al, 1992;JIMENEZ et al, 1995). Recently, the serological detection and isolation of BIV (BIVCRI) in Costa Rica has been reported (HIDALGO et al, 1995).…”