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.
To analyze the co-occurrence of virulence genes among bovine and human commensal E. coli strains and visualize it in the network interface, we constructed a pairwise co-occurrence matrix for each gene (Supplemental Table S8). Only one co-occurrence
S evere fever with thrombocytopenia syndrome (SFTS) is caused by the species Dabie bandavirus (family Phenuiviridae, genus Bandavirus), generally called severe fever with thrombocytopenia syndrome virus (SFTSV) (1,2). Cases of SFTS were identified in patients in China during 2009 (3) and subsequently in Japan and South Korea (2,4). Clinical signs include high fever, fatigue, gastrointestinal symptoms, neurologic symptoms, thrombocytopenia, leukocytopenia, and multiorgan failure (5). SFTS is potentially fatal, and mortality rates have reached 27% in Japan (6). Although the clinical information regarding SFTS in most animals is unclear, cats show fatal symptoms similar to those in humans (7). Enzootic SFTSV transmission is primarily tickborne; tick bites can also spread the virus to humans (8) and animals (9). Human-to-human transmission occurs rarely through contact with infected blood, body fluids, or mucus (10) and possibly by aerosols (11). In this study, we provide evidence for the direct cat-to-human transmission of the virus, leading to a nosocomial outbreak of SFTSV infection. The Study Confirmatory testing of veterinary personnel samples was performed at the Laboratory of Microbiology, Miyazaki Prefecture Institute for the Public Health and Environment, Miyazaki, Japan. Cat sample analysis was performed at the Center for Animal Disease Control, University of Miyazaki. A 1-year-old male domestic cat was hospitalized on August 15, 2018, with jaundice, poor appetite, vomiting, and a rectal temperature of 40.4°C. Hematologic examination showed leukocytopenia (1,080 cells/µL, reference range 4-30 × 10 3 cells/µL), thrombocytopenia (19,000 cells/µL, reference range 9-90 × 10 4 cells/µL), and an increased level of total bilirubin (3.1 mg/dL, reference range 0-0.5 mg/dL) (12) (Table). The cat died 3 days after hospitalization. Serum samples, saliva samples, and anal swab specimens (sampled on the first day of hospitalization) were sent to the Center for Animal Disease Control, University of Miyazaki, for molecular test targeting the small segment RNA of SFTSV by reverse transcription PCR (RT-PCR) and real-time RT-PCR (3). The amounts of SFTSV RNA were quantified as RNA copies per milliliter of serum. We detected a viral load of 1.5 × 10 11 copies/mL (Table). During hospitalization, the cat came into contact with a veterinarian (44-year-old woman) and a veterinary technician (20-year-old woman). During contact, both veterinary personnel wore protective clothing (gloves and surgical masks), but their eyes remained unprotected; they were not bitten or scratched by the cat. In addition, neither was bitten by ticks. After the death of the cat, symptoms consistent with SFTS developed in both veterinary personnel (Figure 1). Ten days after the death of the cat, on August 27, the veterinarian (patient 1) was hospitalized with a high fever (body temperature 39.2°C),
The bovine MHC (BoLA) class II DRB3 alleles are associated with polyclonal expansion of lymphocytes caused by bovine leukemia virus (BLV) infection in cattle. To examine whether the DRB3*0902 allele, one of the resistance-associated alleles, is associated with the proviral load, we measured BLV proviral load of BLV-infected cattle and clarified their DRB3 alleles. Fifty-seven animals with DRB3*0902 were identified out of 835 BLV-infected cattle and had significantly lower proviral load (P<0.000001) compared with the rest of the infected animals, in both Japanese Black and Holstein cattle. This result strongly indicates that the BoLA class II DRA/DRB3*0902 molecule plays an important immunological role in suppressing viral replication, resulting in resistance to the disease progression.
A key virulence factor of enterohaemorrhagic Escherichia coli (EHEC) is the bacteriophage-encoded Shiga toxin (Stx). Stxs are classified into two types, Stx1 and Stx2, and Stx2-producing strains are thought to cause more severe infections than strains producing only Stx1. Although O26 : H11 is the second most prevalent EHEC following O157 : H7, the majority of O26 : H11 strains produce Stx1 alone. However, Stx2-producing O26 strains have increasingly been detected worldwide. Through a large-scale genome analysis, we present a global phylogenetic overview and evolutionary timescale for E. coli O26 : H11. The origin of O26 has been estimated to be 415 years ago. Sequence type 21C1 (ST21C1), one of the two sublineages of ST21, the most predominant O26 : H11 lineage worldwide, emerged 213 years ago from one of the three ST29 sublineages (ST29C2). The other ST21 lineage (ST21C2) emerged 95 years ago from ST21C1. Increases in population size occurred in the late 20th century for all of the O26 lineages, but most remarkably for ST21C2. Analysis of the distribution of stx2-positive strains revealed the recent and repeated acquisition of the stx2 gene in multiple lineages of O26, both in ST21 and ST29. Other major EHEC virulence genes, such as type III secretion system effector genes and plasmid-encoded virulence genes, were well conserved in ST21 compared to ST29. In addition, more antimicrobial-resistance genes have accumulated in the ST21C1 lineage. Although current attention is focused on several highly virulent ST29 clones that have acquired the stx2 gene, there is also a considerable risk that the ST21 lineage could yield highly virulent clones.
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