Shiga toxin-producing Escherichia coli O157:H7 (STEC) cause food-borne illness that may be fatal. STEC strains enumerate two types of potent Shiga toxins (Stx1 and Stx2) that are responsible for causing diseases. It is important to detect the E. coli O157 and Shiga toxins in food to prevent outbreak of diseases. We describe the development of two multi-analyte antibody-based lateral flow immunoassays (LFIA); one for the detection of Stx1 and Stx2 and one for the detection of E. coli O157 that may be used simultaneously to detect pathogenic E. coli O157:H7. The LFIA strips were developed by conjugating nano colloidal gold particles with monoclonal antibodies against Stx1 and Stx2 and anti-lipid A antibodies to capture Shiga toxins and O157 antigen, respectively. Our results indicate that the LFIA for Stx is highly specific and detected Stx1 and Stx2 within three hours of induction of STEC with ciprofloxacin at 37 °C. The limit of detection for E. coli O157 LFIA was found to be 10⁵ CFU/mL in ground beef spiked with the pathogen. The LFIAs are rapid, accurate and easy to use and do not require sophisticated equipment or trained personnel. Following the assay, colored bands on the membrane develop for end-point detection. The LFIAs may be used for screening STEC in food and the environment.

In recent years, the clinical cases of ENTV-2 infection have increased and become prevalent in several provinces of China. In this study, we reported the occurrence of ENTV-2 in one goat farm in Chongqing, southwest China. The complete genome of an emerged ENTV-2 isolate (designated as CQ2) was sequenced with 7468 bp in length. Phylogenetic analysis revealed that ENTV-2 consisted of two main lineages. Lineage 1 was composed of Chinese strains and could be subdivided into five sublineages. CQ2 and the other six recent isolates from China were clustered in sublineage 1.5; however, CQ2 was significantly different from the other six isolates. Furthermore, recombination analysis suggested that CQ2 might be a recombinant variant derived from sublineage 1.5 and sublineage 1.2 strains, with the recombination region in areas of pro and pol genes. In conclusion, we sequenced and analyzed the complete genome of a potential ENTV-2 recombinant, which may contribute to our understanding of the genetic variation and evolution of ENTV-2 in China.

Bovine leukemia virus (BLV), the most prevalent neoplastic disease of cattle worldwide, is the causative agent of enzootic bovine leukosis. Polymorphisms in the bovine leukocyte antigen (BoLA)-DRB3 gene can influence host immune responses to pathogens, including BLV. However, the associations between specific BoLA-DRB3 alleles, BLV proviral load (PVL), a useful index for estimating disease progression and transmission risk, and BLV infection in Chinese cattle remain unknown. In this study, we identified 28 previously reported alleles in 289 Holstein cattle from Shandong Province, China, using polymerase chain reaction sequence-based typing. We further investigated whether BoLA-DRB3 polymorphisms influenced infection status and identified BoLA-DRB3*011:01 as an allele associated with susceptibility to BLV infection. An association analysis of allele frequencies between cattle with high and low PVL demonstrated that BoLA-DRB3*014:01:01 was significantly associated with low PVL. Farms with a higher frequency of cattle carrying BoLA-DRB3*014:01:01 had lower mean PVL values than farms with a lower frequency, indicating that resistant alleles are linked to low PVL levels. To our knowledge, this is the first study to demonstrate that BoLA-DRB3 polymorphisms associate with differential susceptibility to BLV infection and PVL in Holstein cattle in China. These findings may contribute to BLV control and eradication efforts through genetic selection.

Bovine leukemia virus (BLV) is widespread globally and causes economic losses in the cattle industry. Shandong Province plays a significant role in China's livestock industry, with an increasing importance in food of Holstein and Angus cattle. However, BLV prevalence in Holstein and Angus breeds in Shandong Province remains unclear. In particular, there are no reports of BLV prevalence of Angus cattle in field surveys worldwide. In this study, 613 samples from six large‐scale farms (> 1000 heads per farm) in Binzhou and Weifang cities were screened for BLV antibodies (gp51) using an enzyme‐linked immunosorbent assay. The samples included 303 Angus (beef) and 310 Holstein (dairy) cattle. All Angus breeding samples from the three farms were BLV‐negative at both the animal‐ and herd‐level prevalences. In contrast, 62 of 310 Holstein cattle (20.0%) from three dairy farms were positive for BLV antibodies. For example, 35/110 (31.8%), 19/100 (19.0%), and 8/100 (8.0%) samples from the D, E, and F farms, respectively, were BLV‐positive. Notably, the animal‐ and herd‐level prevalences for Holstein cattle exhibited 20% and 100% positivity, respectively. These findings offer significant insights into the BLV status of Holstein and Angus cattle in Shandong Province, China.

Bovine leukaemia virus (BLV) infects cattle, integrates into the host genome as a provirus, and induces a persistent infection that remains asymptomatic but can cause leukaemia/lymphoma. Most BLV‐infected cell clones are created by massive depletion, and a few of these infected cell clones expand through the mitotic cycle, leading to the onset of lymphoma. Bovine lymphocyte antigen (BoLA)‐DRB3 polymorphism is associated with susceptibility to BLV‐induced leukemogenesis. However, whether BoLA‐DRB3 polymorphism affects the clonality of BLV‐infected cells in vivo remains unknown. Here, we investigated whether lymphoma integration sites have specific features in cattle with varying susceptibility to lymphoma. Genomic DNA was extracted from 99 BLV‐infected Holstein cattle with lymphoma in a nationwide survey across Japan, and the integration sites were analysed using BLV proviral DNA‐capture sequencing, which we had previously developed. Among the integration sites identified in 99 animals, no identical sites were confirmed. Comparison of integration sites between cattle with susceptible and resistant BoLA‐DRB3 alleles showed no significant differences in the distribution of integration sites on the chromosome and in the genes and intergenic regions. With respect to the orientation of the proviruses, or proviral structures between individuals with resistance or susceptibility to lymphoma. In contrast, resistant animals showed a significantly higher proportion of monoclonal cell types than susceptible animals. In summary, the BoLA‐DRB3 polymorphism affects BLV clonality; for example, there is massive depletion and clonal expansion of infected cell clones in fully transformed clones obtained from BLV‐infected cattle with lymphoma.