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Isolation of Bovine leukemia virus from cows with persistent lymphocytosis in Iraq.

ABSTRACT: This is the first study to report on the isolation of bovine leukemia virus (BLV) from peripheral blood mononuclear cells of two cross bred cows in Iraq. The cattle were seropositive by ELISA when selected while being surveyed for the detection of BLV. Among six cows, two were cases of persistent lymphocytosis (PL). Cytopathology was characterized by the formation of multinucleated giant cells (syncytia) and cytoplasmic vacuoles. Moreover, the viruses produced clear plaques on the monolayer of the primary fetal calf kidney (FCK) cells. Inhibition of plaque formation by BLV-antisera suggested a diagnosis of BLV, which was further confirmed by PCR. Cells infected with the isolates were positive to a monoclonal antibody against the viral gp51 trans-membrane glycoprotein by immunocytochemistry. Both isolates replicated and induced cytopathic effects in bovine and human cell line cultures. Phylogenetic analysis based on partial gp51 env gene sequences revealed that Iraqi strain highly homogenous with Turkey strain (100%) and had 1% distance value with other world strains. In conclusion, this present study found that BLV-infected cattle with PL can be a source for viral isolation, and the cytopathological features of the virus infection are arranged and differ depending on the cell type. This is the first study to report on the isolation of the EBL virus in Iraq, and it provides the basis for further studies about a BLV Iraqi strain that can help control this disease.

SUBMITTER: Khudhair YI

PROVIDER: S-EPMC8426556 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background and aimBovine trichomoniasis, caused by Tritrichomonas foetus, is a venereal disease that is distributed in many countries, including Iraq. Compared with other abortive infectious diseases, prevalence of T. foetus is expected to be relatively low in the field by veterinarians. This study aimed to estimate the prevalence of T. foetus in aborted cows by conventional polymerase chain reaction (PCR) and phylogenetic analysis of local T. foetus isolates was documented in the National Center for Biotechnology Information as the first sequenced isolates from Iraq.Materials and methodsVaginal fluids were collected from 62 aborted cows and examined by PCR. Data were reported for the following parameters: Vital signs (body temperature and respiratory and pulse rates), age (<4, 4-8, and >8 years), reproductive health status (premature calving, embryonic death, pyometra, and healthy newborn), breed (pure or crossbred), type of breeding (natural or artificial), bull-to-cow ratio (1:<10, 1:10-20, and 1:>20), contact of cow with bull(s) from other farmers (yes or no), and contact with stray animals (dogs and cats).ResultsA total of 20.97% of aborted cows were positive for T. foetus. Phylogenetic analysis for 10 positive local T. foetus isolates demonstrated high identity with the Thai (MN560972.2) and Chinese (MH115435.1) isolates, with an identity range of 98.8%-99.5% and 98.6%-99.3%, respectively. Clinical data showed that the vital signs differed insignificantly between cows positive and negative for T. foetus. Prevalence and risk of infection increased significantly in <4-year-old, early calving, embryonic death, crossbred, and naturally inseminated cows that had direct contact with bulls from other farmers, and contact with stray animals. Fetal pneumonia and death of premature calves were significant among positive aborted fetuses.ConclusionTritrichomonas foetus is highly prevalent in aborted cows in Iraq and phylogenetic analysis demonstrated an identity between the local and global isolates, that is, Thai and Chinese, of cats.

Project description:Bovine leukemia virus (BLV) is widespread in global cattle populations, but the effects of its infection on milk quantity and quality have not been clearly elucidated in animal models. In this study, 30 healthy first-lactation cows were selected from ≈2,988 cows in a BLV-free farm with the same criteria of parity, age, lactation number, as well as milk yield, SCS, and composition (fat, protein, and lactose). Subsequently, these cows were randomly assigned to the intervention (n = 15) or control (n = 15) group, and reared in different cowsheds. Cows in the intervention group were inoculated with 1 × phosphate-buffered solution (PBS) resuspended in peripheral blood mononuclear cells (PBMC) from a BLV-positive cow, while the controls were inoculated with the inactivated PBMC from the same individual. From June 2016 to July 2021, milk weight (kg) was automatically recorded by milk sensors, and milk SCS and composition were originated from monthly performed dairy herd improvement (DHI) testing. Fluorescence resonance energy transfer (FRET)-qPCR and ELISA showed that cows in the intervention group were successfully infected with BLV, while cows in the control group were free of BLV for the entire period. At 45 days post-inoculation (DPI), the numbers of whole blood cells (WBCs) (P = 0.010), lymphocytes (LYMs) (P = 0.002), and monocytes (MNCs) (P = 0.001) and the expression levels of IFN-γ (P = 0.013), IL-10 (P = 0.031), and IL-12p70 (P = 0.008) increased significantly in the BLV infected cows compared to the non-infected. In lactation numbers 2-4, the intervention group had significantly higher overall milk yield (P < 0.001), fat (P = 0.031), and protein (P = 0.050) than the control group, while milk SCS (P = 0.038) and lactose (P = 0.036) decreased significantly. Further analysis indicated that BLV infection was associated with increased milk yield at each lactation stage in lactation numbers 3-4 (P = 0.021 or P < 0.001), but not with SCS and milk composition. Together, this 4-year longitudinal study revealed that artificial inoculation of BLV increased the milk yield in cows in this BLV challenge model.

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Isolation of Bovine leukemia virus from cows with persistent lymphocytosis in Iraq.

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