Detección molecular y serológica del virus de la leucosis bovina en una población de vacas Holstein, de Colombia

Abstract

La leucosis bovina enzoótica (LBE) es una enfermedad maligna, sistémica, de alta morbilidad (70 %) y baja mortalidad, ocasionada por la infección con el virus de la leucosis bovina (BLV). La LBE afecta principalmente los bovinos de leche, disminuyendo la producción de leche de 2.5 a 5 % respecto al hato; además, causa inmunosupresión, permitiendo que otros patógenos afecten la producción y reproducción de los animales. El objetivo fue determinar la presencia o ausencia del BLV a través de dos metodologías de diagnóstico: una técnica serológica (ELISA) y una técnica molecular (PCR). Se tomaron 1,000 muestras de sangre de vacas Holstein distribuidas en 10 municipios lecheros del Departamento de Antioquia. Se realizó una PCR para obtener un producto de PCR de 444 pb correspondiente a una región altamente conservada del gen env viral, que codifica para la proteína de envoltura gp51. Se realizó un ELISA indirecta contra la proteína gp51 para estos mismos animales. La PCR detectó un número menor de muestras positivas (474) que la prueba ELISA (546). La sensibilidad de la PCR fue de 74.91 % y su especificidad fue de 85.68 % respecto al ELISA. El grado de concordancia entre pruebas fue moderado (kappa=0.59). El municipio con la mayor prevalencia molecular fue Rionegro (73.91 %), mientras que la mayor seroprevalencia se registró en el municipio de El Retiro (85.19 %). El BLV ha aumentado su presencia en la región; la detección de este patógeno no solo permitirá determinar la prevalencia, sino también usar los datos obtenidos en programas de prevención y control de la enfermedad.

Masked Genotype 6 of Bovine Leukemia Virus Is Found in Colombian Cattle

“…Molecular epidemiology studies of BLV worldwide an in this case in Colombia, makes it possible to identify circulating strains in specific regions to propose and build public policies aimed to control and, in the future, eradicate this virus which has been seen to produce problems not only in cattle but also has been reported as a possible risk factor involved in humans pathologies [32][33][34][35]. In the other hand, variability of genotypes as well as results of structural and functional properties of its envelope proteins [36] provide useful information for research focused on vaccines production with specific strains, that in the case of Colombia, will be appropriate to include conserved epitopes shared between genotypes 1, 6 and 3 according to the results obtained in this study and previously reported [31]. In addition, phylogenetic studies are important to understand the geographical distribution of the virus and thus, identify conserved and hypervariable regions including specific mutations that could be related with different levels of virulence or pathogenicity [6,[37][38][39][40][41].…”

“…However, topology of some trees shows different clusters in the same genotype, leading to the question if the amplification of the 444 bp segment of env region could efficiently identify all the current genotypes or instead, it mimics the presence of other circulating genotypes. Now, considering the current situation of BLV in Colombia, even if it was determined the seroprevalence earlier [1], there are few studies [31] in which the molecular epidemiology of the virus has been determined. The aim of this study was to identify the circulating genotype of BLV along the country in order to deep in the knowledge of the current situation of BLV and to reveal the possibility of masked genotypes, unable to identify with the primers suggested by OIE.…”

Risk factors associated with enzootic bovine leukosis in Boyacá and Cundinamarca municipalities, Colombia

“…In Colombia, percentages of antibodies against BLV have been determined in 13.5% of cattle from Toca (Boyacá) using Göttingen hematological keys and ELISA ( Pulido-Medellín et al , 2017 ), in 21.8% of individuals from the department of Santander ( Vargas-Niño et al , 2018 ), in 79.17%, 53.74%, and 46.67% in the Oriente, Norte, and Valle de Aburrá subregions (Antioquia), respectively ( Úsuga-Monroy et al , 2018a ), 31.1% in Sotaquirá (Boyacá) ( Bulla-Castañeda et al , 2021 ), 14.64% in Puerto Boyacá ( Naranjo et al , 2022 ), and 31.1% of the animals sampled in Paipa (Boyacá) ( Jiménez Sánchez et al , 2022 ). Variations occur due to the number of animals sampled, management practices, and production intensification, as well as the geographical location of the farms since it has been reported that there is a greater tendency to seropositivity to the disease in farms with temperate climate and higher altitude, that is mainly associated with sanitary and management practices such as re-use of needles, rectal palpation gloves, natural matting, among others ( Vásconez-Hernández et al , 2017 ).…”

Bovine leukaemia virus DNA in fresh milk and raw beef for human consumption

“…This retrovirus is closely related to the types of human lymphotropic T-cell leukaemia virus (HTLV-1 and -2) [3]. BLV integrates its genome in target bovine cells, so that all infected animals are persistently infected and become carriers of the virus during the course of their lives, thereby having a negative impact on the animals' immune system and, consequently, induces losses in milk production, poorer yield regarding weight and induced abortions in the animals [1,4,5].…”