Screening for Japanese Black cattle herds at risk of bovine leukemia virus transmission based on the presence of persistent lymphocytosis.

This study aimed to develop a screening method to identify Japanese Black (JB) cattle farms at high risk of bovine leukemia virus (BLV) transmission. We introduced a recently established lymphocyte count (LC) cut-off to detect cattle with persistent lymphocytosis (PL). To identify high-risk farms, we examined the relationship between the proportion of cattle with PL and the mean blood proviral loads (PVL) per farm.

BoLA-DRB3*15:01 allele is associated with susceptibility to early enzootic bovine leukosis onset in Holstein-Friesian and Japanese Black cattle.

Enzootic bovine leukosis (EBL) is typically observed in cattle older than 3 years, but some cases of onset in cattle younger than 3 years have been reported in Japan. BoLA-DRB3 polymorphisms are associated with susceptibility to EBL onset. However, little is known about the relationship between the polymorphisms and EBL onset in young cattle.

Phylogenetic analysis based on whole genome sequence of bovine leukemia virus in cattle under 3 years old with enzootic bovine leukosis.

Enzootic bovine leukosis (EBL) is one of bovine neoplasms caused by bovine leukemia virus (BLV). Although EBL is typically observed in cattle over 3 years old, several cases of EBL onset in cattle under 3 years old have been reported in Japan. The mechanism for EBL onset in young cattle remains unclear.

Enzootic bovine leukosis in a 21-month-old Japanese Black cow with high susceptibility.

A 21-mo-old Japanese Black beef cow had swollen mandibular and superficial cervical lymph nodes. Fine-needle aspiration cytology of the superficial cervical lymph node revealed large lymphoblasts with mitoses present. The bovine leukemia virus (BLV) proviral load was relatively high, and phylogenetic analysis of the whole BLV genome classified the BLV strain as one with high viral replication activity.

Risk factors associated with the within-farm transmission of bovine viral diarrhea virus and the incidence of persistently infected cattle on dairy farms from Ibaraki prefecture of Japan.

For understanding the factors affecting bovine viral diarrhea virus (BVDV) transmission, this study investigated the distribution of BVDV and the epidemiological features of persistently infected (PI) cattle in Ibaraki Prefecture of Japan, and identified farm-level risk factors associated with BVDV infection, with a focus on within-farm transmission and PI animal detection. Among all 377 dairy farms, forty-four PI cattle were identified on 22 farms. Thirty-eight and six PI cattle were born on their current farms or purchased, respectively.

A hematologic key for bovine leukemia virus screening in Japanese black cattle.

The European Community's leukosis key (EC key) is a well-known hematologic method for detecting bovine leukemia virus (BLV) infection in dairy cattle. The key identifies infected cattle with persistent lymphocytosis via a combination of lymphocyte count (LC) and age. Using the EC key to identify BLV-infected Japanese black (JB) cattle is problematic, however, given the inherently lower LCs of JB cattle compared to dairy cattle.

Spatial transmission of H5N6 highly pathogenic avian influenza viruses among wild birds in Ibaraki Prefecture, Japan, 2016-2017.

From 29 November 2016 to 24 January 2017, sixty-three cases of H5N6 highly pathogenic avian influenza virus (HPAIV) infections were detected in wild birds in Ibaraki Prefecture, Japan. Here, we analyzed the genetic, temporal, and geographic correlations of these 63 HPAIVs to elucidate their dissemination throughout the prefecture. Full-genome sequence analysis of the Ibaraki isolates showed that 7 segments (PB2, PB1, PA, HA, NP, NA, NS) were derived from G1.