A case of chronic lymphocytic leukemia (CLL) with plasmacytic differentiation was detected in a 5-year-old Holstein cow not infected with bovine leukemia virus. Generalized lymph node swelling was due to proliferation of tumor cells, and perivascular tumor cell infiltration or accumulation was observed in various sites of the body. Neoplastic cells were polymorphic, being divided into lymphoid and plasmacytoid cells. These cells were positive for CD20 and CD5, and plasmacytoid cells showed positive reactivity for cytoplasmic immunoglobulin M (cIgM) (μ chain and λ chain). In some parts, cIg-negative large lymphoid cells accumulated into clusters, and this implies a histological shift of CLL to large cell lymphoma (large cell transformation). This lymphoma with CD5 expression and relatively scant cytoplasm in plasmacytoid cells was readily distinguishable from lymphoplasmacytic lymphoma characterized by CD5 negativity and abundant cytoplasm in neoplastic plasma cells.

In 2018, an outbreak of classical swine fever (CSF) was identified in Japan for the first time in 26 years. To prevent the spread of CSF to wild boars, bait vaccination with a commercial vaccine derived from the live attenuated C-strain for wild boars has been introduced in Japan since March 2019. Although conventional and real-time RT-PCR methods are suitable for screening and confirmation of suspected cases of the disease, neither of the methods used in Japan can discriminate between CSF virus field strains and live attenuated vaccines. Currently, Sanger sequencing of PCR products is used to distinguish them. In recent years, nanopore sequencing, which is based on a novel sequencing technology, has been adopted for laboratory diagnosis. To save the time and effort required for Sanger sequencing of PCR products, we aimed to determine whether nanopore sequencing would be applicable to CSF virus strain genotyping. PCR products from twenty-nine wild boar samples were evaluated and nanopore sequencing succeeded in discriminating between vaccine and epidemic strains in 28 of 29 samples in less than 90 minutes of total examination time per test. The comparative studies of the sequencing accuracy between Sanger and nanopore sequencing indicated a concordance of ＞96% suggesting that nanopore sequencing could be a promising method for CSF virus strain genotyping despite the short examination time.

Rectal samples from 39 cattle from 10 farms and 124 swine from 22 farms collected at a slaughterhouse in Nagoya city, between 2018 and 2019, were examined to determine the prevalence of Escherichia albertii (E. albertii ) among livestock in the Tokai region. Screening-positive samples were obtained from 11 (50%) of the swine farms, and E. albertii was isolated from 20 (16.1%) swine from 10 (45.5%) farms. Of the 20 porcine isolates, 17 isolates (85%) were resistant to at least one antimicrobial tested. Pulsed-field gel electrophoresis (PFGE) analysis revealed that 20 isolates were classified into five groups. In an additional examination in 2020, 18 isolates were obtained from 114 swine samples from three farms positive for E. albertii. All the 18 isolates were classified into the same PFGE groups by farm. Thus, E. albertii continued to exist on each farm for a long period of time.