Bovine leukemia virus (BLV) is a retrovirus that causes lymphoma in cattle worldwide and has also been associated with breast cancer in humans. The mechanism of BLV infection in humans and its implication as a primary cause of cancer in women are not known yet. BLV infection in humans may be caused by the consumption of milk and milk-products or meat from infected animals. Breast cancer incidence rates in Brazil are high, corresponding to 29.5% a year of cancer cases among women. In 2020, an estimated 66,280 new cases of breast cancer are expected, whereas in 2018 breast cancer has led to 17,572 deaths, the highest incidence and lethality among cancers in women in this country that year. BLV infection occurrence ranges from 60 to 95% in dairy herds. In addition, there are some regions, such as the Minas Gerais State, southeastern Brazil, where the population traditionally consume unpasteurized dairy products. Taken together, this study aimed to verify if there is a higher association between breast cancer and the presence of BLV genome in breast tissue samples within this population that consumes raw milk from animals with high rates of BLV infection. A molecular study of two BLV genes was carried out in 88 breast parenchyma samples, between tumors and controls. The amplified fragment was subjected to BLV proviral sequencing and its identity was confirmed using GenBank. BLV proviral genes were amplified from tumor breast parenchyma samples and healthy tissue control samples from women, revealing a 95.9% (47/49) and 59% (23/39) positivity, respectively. Our results show the highest correlation of BLV and human breast cancer found in the world to date within the population of Minas Gerais, Brazil.
Molecular detection of bovine immunodeficiency virus (BIV) in bovines from the state of Minas Gerais, Brazil [Detecção molecular do vírus da imunodeficiência bovina (BIV) em bovinos do estado de Minas Gerais, Brasil]
Reproductive performance of dairy cows has a direct impact on herd productivity. Infectious agents, such as Bluetongue Virus (BTV) and Bovine Leukemia Virus (BLV), are associated with reproductive failure. However, it remains unknown if these viruses are present in the uterus and cause gestational loss. This study used molecular methods to assess if BTV and BLV can be detected in the uterus of serologically positive dairy cows with a record of abortions, stillbirths and repeat breeding (n=23) and without a record of reproductive problems (n =23). The cows came from three dairy herds of the state of Minas Gerais, Brazil. BTV was not detected in any of the uterine biopsies. Proviral DNA of BLV was detected in 54.5 % of the seropositive cows, but positivity for BLV in the uterus was not associated with the existence of reproductive problems. In conclusion, this study shows that BLV, but not BTV, is present in the uterus of seropositive cows, regardless of reproductive performance. Key words: Bovines. Reproduction. Uterus. BTV. BLV. associados à ocorrência de falhas reprodutivas. Entretanto, não se sabe se estes vírus poderiam estar presentes no útero resultando nas perdas gestacionais. Este estudo utilizou métodos moleculares para investigar se os vírus BTV e BLV estão presentes no úterio de vacas leiteiras sorologicamente positivas com histórico de abortos, natimortos e repetição de cio (n=23) e em vacas sem histórico de problema reprodutivos (n =23) provenientes de três rebanhos leiteiros localizados no estado de Minas Gerais, Brasil. Não foi detectado BTV em nenhuma amostra de biópsia uterina. Por outro lado, o DNA proviral de BLV foi detectado no útero de 54.5 % das vacas soropositivas, independentemente da ocorrência de problemas reprodutivos. Conclui-se que o vírus BLV, ao contrário do BTV está presente no útero de vacas soropositivas, entretanto, sem associação com o desempenho reprodutivo. Palavras-chave: Bovinos. Reprodução. Útero. BTV. BLV.
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