Monika Olech, Piotr Kubiś, Czesława Lipecka, Andrzej Junkuszew, Tomasz M. Gruszecki and Jacek Kuźmak
The aim of this study was to investigate the presence of proviral DNA and colostral antibodies in lambs born to and fed by ewes infected with small ruminant lentiviruses (SRLV). It was demonstrated that all 20 lambs tested 24 h after colostrum ingestion were serologically positive with high antibody titres. These gradually decreased with time, and at week 12 all lambs were seronegative. Twenty percent of lambs tested at the 2nd week postpartum were provirus positive by qPCR as a result of consumption of infected colostrum or in utero infection. When tested at three months of life, 95% of the lambs were provirus positive, probably as a result of horizontal transmission of the virus. Since these animals could play an important role in the early propagation of SRLV to susceptible herdmates, early removal of provirus-positive animals could help to prevent new infections.
Aneta Pluta, Marzena Rola-Łuszczak, Monika Olech and Jacek Kuźmak
In this study the sequences of the long terminal repeat (LTR) of field isolates of the bovine leukaemia virus (BLV) were analysed. These isolates came from emerging cases of BLV infection in cattle from herds having BLV-free status. We found several sequence variations within regulatory motifs in the LTRs like GRE, DAS and interferon binding site. These mutations can possibly affect transcriptional activity of the virus, leading to its silencing.
Monika Olech, Marzena Rola-Łuszczak, Bożenna Kozaczyńska, Piotr Kubiś, Aneta Pluta, Anna Gil and Jacek Kuźmak
In the study, a 122 bp fragment of gag gene encoding immunodominant epitope on capsid protein of small ruminant lentiviruses (SRLVs) found in sheep was amplified by PCR and analysed by SSCP and sequencing. Out of 30 DNA samples, five showed different migration patterns, demonstrating the individual variations within gag sequences, which were confirmed afterwards by sequence analysis. In two samples nucleotide changes yielded amino acid substitutions highlighting the conservative nature of gag encoded immunoreactive epitope but also potencial insensitivity of a single-strain-based immunoassay.
Czesława Lipecka, Andrej Junkuszew, Jacek Kuźmak, Tomasz M. Gruszeck, Bożena Kozaczyńska, Monika Olech, Wiktor Bojar and Zbigniew Osiński
The study included a sheep flock comprising five genetic groups. The ELISA was applied to perform constant monitoring (every six months) for the infection of ewes with small ruminant lentivirus (SRLV). The research results demonstrated a negative effect of SRLVs infection on lamb rearing that, depending on the genetic group, proved to be lower 1.3%-1.4% compared to the seronegative mothers. At relatively equal fertility (94%-100%) and more differentiated prolificacy (179%-198%) in all the examined groups (except the Suffolk breed), a rearing index was higher in the seronegative animals 6.8%-24.1% compared to the seropositive mothers. The Suffolk breed proved to be the genetic group most susceptible to SRLV infection. A prolificacy of infected ewes was 10% lower, a lamb rearing rate was 13% lower , and a general reproductive performance was 18% lower in comparison to healthy ewes.