Evaluation of the natural perinatal transmission of bovine leukaemia virus

Abstract

The perinatal transmission of bovine leukaemia virus (BLV) plays a critical role in the spread and persistence of BLV infection in cattle herds. The purpose of this study was to examine the frequency of perinatal infections in an area in Japan and investigate some risk factors associated with infection. Altogether, 129 calves born to BLV-infected cows in a herd in Japan were tested for infection immediately after birth and again at one month of age using nested PCR. Twenty-four calves (18.6 per cent) were infected with BLV, of which 14 (10.8 per cent) and 10 (7.7 per cent) calves were infected via the transplacental and the birth canal routes, respectively. Maternal viral loads, breed, the presence or absence of assistance during parturition and the number of births per dam were evaluated to investigate risk factors associated with infection. Maternal viral load was significantly correlated with the frequency of perinatal infection, and more than 40 per cent of newborn calves born to dams with high viral loads were infected with BLV. The results of this study could contribute towards developing effective eradication programmes by providing necessary data for replacement of breeding cow in the field.

Stable infection of a bovine mammary epithelial cell line (MAC-T) with bovine leukemia virus (BLV)

“…These results have two major implications. The fact that BLV can infect the bovine epithelial mammary gland supports the possibility of viral transmission through breastfeeding, an issue that nowadays is still controversial (Gutiérrez et al, 2015;Mekata et al, 2015;Nagy et al, 2007;Van Der Maaten et al, 1981). Some studies demonstrate that the virus is present in the milk of infected cattle and others authors ensure that milk maternal antibodies protect against calf infection.…”

In vitro and in vivo antivirus activity of an anti-programmed death-ligand 1 (PD-L1) rat-bovine chimeric antibody against bovine leukemia virus infection

“…As 7-month-old calf was inoculated Boch4G12 at 13 weeks post-inoculation, we confirmed that the disease in the experimentally infected calf developed to the AL stage after the acute infection phase (data not shown). Moreover, the provirus loads in both tested animals were categorized as low risk for transmitting BLV to other cattle [40], indicating that the difference in background of the animals had little effect on the results of this study. Another possible explanation is that 4G12 was destabilized by anti-drug antibodies; whereas, Boch4G12 was not since the 7-month-old calf had a less developed immune system.…”

“…BLV provirus loads were measured as previously described [40] with some modification. Briefly, genomic DNA was extracted from 1–5×10 6 PBMCs of the antibody-inoculated cattle using the Wizard® Genomic DNA Purification Kit (Promega).…”

Enzootic bovine leukosis accompanied by splenomegaly in an 8-month-old calf

“…al., 1975). Additionally, in the case of calves whose mother showed high provirus loads, more than 40% of the infants have been confirmed BLV positive whereas BLV positive rates were only 9.4% in the calves born from mothers with low provirus loads (Mekata et. al., 2015).…”