Genetic analysis of the pX region of bovine leukemia virus genotype 1 in Holstein Friesian cattle with different stages of infection
Por:
Montero Machuca, Neli, Tortora Perez, Jorge Luis, Gonzalez Mendez, Ana Silvia, Garcia-Camacho, Angelica Lucia, Marin Flamand, Ernesto, Ramirez Alvarez, Hugo
Publicada:
1 ene 2022
Resumen:
The pX genetic region of bovine leukemia virus (BLV) includes four genes
with overlapping reading frames that code for the Tax, Rex, R3, and G4
proteins. These proteins are involved in the regulation of
transcriptional and post-transcriptional viral expression, as well as
having oncogenic potential. Our goal was to investigate the
pathogenicity of the pX region of BLV genotype 1 in terms of
lymphocytosis, lymphomas, and proviral DNA load. We screened 724
serological samples from mixed-age Holstein Friesian cattle from six
states in Mexico. Peripheral blood leukocytes (PBLs) were isolated from
whole blood with anticoagulant, and genomic DNA was extracted from the
PBLs using a commercial kit. Then, a set of primers that hybridize in
conserved regions of the BLV pX region were used, which allowed for PCR
standardization to detect proviral DNA in infected cells. Positive
amplicons were sequenced using the Sanger method, resulting in
1156-nucleotide-long final sequences that included the four pX region
genes. The experimental group consisted of 30 animals. Twelve of these
had lymphocytosis, six had lymphoma, and 12 were apparently healthy
cattle without any signs of lymphocytosis or lymphoma. The presence of
lymphoma was detected in six bovine tumor tissues using histopathology,
and the presence of BLV was detected by in situ hybridization.
Phylogenetic analysis demonstrated that the 30 sequences were associated
with genotype 1, and the genetic distance between the sequences ranged
from 0.2% to 2.09%. We identified two sequences in the G4 gene: one
with a three-nucleotide deletion resulting in the loss of a leucine
(AGU_7488L, in a cow with lymphocytosis), and one with a
nine-nucleotide deletion resulting in the loss of leucine, proline, and
leucine (AGU_18A, in a cow without lymphocytosis). Analysis of the PX
region indicated that positive selection had occurred in the G4, rex,
and R3 genes, and we found no difference in proviral DNA load between
the studied groups. We were unable to establish an association between
variations in the pX region and the development of lymphocytosis,
lymphoma, asymptomatic status, or proviral DNA load in BLV-infected
cattle.
Filiaciones:
Montero Machuca, Neli:
Univ Nacl Autonoma Mexico, Virol Genet & Mol Biol Lab, Fac Higher Educ Cuautitlan Vet Med, FES Cuautitlan, Campus 4, Cuautitlan 54714, Estado De Mexic, Mexico
Tortora Perez, Jorge Luis:
Univ Nacl Autonoma Mexico, Dept Biol Sci, Fac Higher Educ, Cuautitlan, Izcalli, Mexico
Gonzalez Mendez, Ana Silvia:
Univ Nacl Autonoma Mexico, Virol Genet & Mol Biol Lab, Fac Higher Educ Cuautitlan Vet Med, FES Cuautitlan, Campus 4, Cuautitlan 54714, Estado De Mexic, Mexico
Garcia-Camacho, Angelica Lucia:
Univ Nacl Autonoma Mexico, Dept Biol Sci, Fac Higher Educ, Cuautitlan, Izcalli, Mexico
Marin Flamand, Ernesto:
Univ Nacl Autonoma Mexico, Dept Biol Sci, Fac Higher Educ, Cuautitlan, Izcalli, Mexico
Ramirez Alvarez, Hugo:
Univ Nacl Autonoma Mexico, Virol Genet & Mol Biol Lab, Fac Higher Educ Cuautitlan Vet Med, FES Cuautitlan, Campus 4, Cuautitlan 54714, Estado De Mexic, Mexico
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