Detection and molecular characterization of bovine leukemia virus in beef cattle presented for slaughter in Egypt

Abstract

Bovine leukemia virus (BLV) is the etiological agent of enzootic bovine leukosis, the most common neoplastic disease of cattle worldwide and a serious problem for the cattle industry. Previous studies have shown the molecular prevalence of BLV and the coexistence of BLV genotype-1 and-4 in Egyptian dairy cattle; however, the molecular characteristics of BLV in Egyptian beef cattle are unknown. Therefore, we collected blood samples of 168 beef cattle from slaughterhouses in three governorates in Egypt. Based on BLV-CoCoMo-qPCR-2 targeting long terminal repeats and nested PCR targeting the env-gp51 gene, the BLV provirus infection rates were found to be 47/168 (28.0%) and 42/168 (25.0%), respectively. Phylogenetic analysis based on 501 bp of the BLV env-gp51 gene from 42 BLV isolates revealed that at least six distinctive strains (b, e, f, g, x, and z) were prevalent in cattle across the examined regions. Furthermore, phylogenetic analysis of the 420 bp sequence of the BLV env-gp51 region of the six strains against 11 known genotypes showed that the strains b, e, f, and g were clustered into genotype-1, and strains x and z were clustered into genotype-4. Our results also indicated that strains b and x exist in both dairy and beef cattle in Egypt. The present study is the first to detect and genotype BLV among beef cattle in Egypt.

Development of Dry and Liquid Duplex Reagent Mix-Based Polymerase Chain Reaction Assays as Novel Tools for the Rapid and Easy Quantification of Bovine Leukemia Virus (BLV) Proviral Loads

“…Thus, we compared two commercial qPCR master mixes, the TBIRD qPCR master mix and the GeneAce qPCR master mix, for the Dual-CoCoMo assay. The TBIRD qPCR master mix, which has high sensitivity, specificity, and cost-effectiveness, is usually used for the Single-CoCoMo assay [10,11,29,31,33,34,[41][42][43][44][45]. In addition, the TBIRD qPCR master mix has been used in several multiplex qPCR assays [46].…”

“…BLV is highly prevalent in most regions, except for some European countries and Oceania [2]. For example, the proportion of BLV-positive cattle ranges from 28.0 to 40.9% in Japan [3], 40.0 to 48.0% in Korea [4], 31.0 to 41.9% in China [5,6], 11.0 to 100% in Thailand [7], 4.8 to 9.7% in the Philippines [8], 21.5 to 28.0% in Egypt [9,10], 37.04% in Myanmar [11], more than 40.0% in the USA [12], and 88.4% of dairy herds in Canada [13]. BLV infects cattle worldwide and has a severe economic impact on the cattle industry [14][15][16].…”

BoLA-DRB3 Polymorphism Associated with Bovine Leukemia Virus Infection and Proviral Load in Holstein Cattle in Egypt

“…Several serological studies have detected BLV infections among dairy cattle in Egypt from different regions, such as Kafr El Sheikh, Alexandria, and Menofia, with infection rates of 15.83% [52], and 20.8% in cows in Kafr El Sheikh, Qalyubia, and Menofia [53]. Our recent investigation of the distribution of BLV provirus revealed a 25-28% BLV infection rate for healthy male beef cattle in three slaughterhouses located in the central and southern regions of Egypt [54] and 21.5% for dairy cattle in five provinces located in the northern, central, and southern regions of Egypt [55]. According to our earlier reports, phylogenetic analysis of the partial env-gp51 sequence of the isolated BLV strains showed that BLV genotypes 1 and 4 coexist in dairy and beef cattle in Egypt from the 12 globally detected genotypes [54,55].…”

“…Our recent investigation of the distribution of BLV provirus revealed a 25-28% BLV infection rate for healthy male beef cattle in three slaughterhouses located in the central and southern regions of Egypt [54] and 21.5% for dairy cattle in five provinces located in the northern, central, and southern regions of Egypt [55]. According to our earlier reports, phylogenetic analysis of the partial env-gp51 sequence of the isolated BLV strains showed that BLV genotypes 1 and 4 coexist in dairy and beef cattle in Egypt from the 12 globally detected genotypes [54,55]. Estimation of BLV PVL among dairy cattle in five provinces in Egypt [55] demonstrated that the BLV PVL level varied among different regions of Egypt with PVL ranging from 7 to 98,725 copies/10 5 cells as calculated by the BLV-CoCoMo quantitative polymerase chain reaction (qPCR)-2 method for the quantitative measurement of PVL [17,56].…”

Anti-BLV antibodies in whey correlate with bovine leukemia virus disease progression and BoLA-DRB3 polymorphism

“…However, owing to the lack of readily available effective treatments and vaccines, BLV infections have spread worldwide (7,8). Currently, 40.9% of the dairy cows over 6 months of age and 28.7% of breeding cattle in Japan (9), 94.2% of dairy herds in the USA (10), 36.7% of the cattle and 78.3% of the herds in Canada (11), over 81.8% of the cattle and 99.1% of the herds in Taiwan (12), over 50% of the cattle and 86.8% of the herds in Korea (13), ∼31-41.9% of the cattle in China (14,15), 4.8-9.7% of the cattle in the Philippines (16), 21.5-28.0% of the cattle in Egypt (17,18), and 9.1-37.04 % of the cattle in Myanmar (19,20) are BLV positive.…”