Failure to induce mucosal disease in cattle persistently infected with bovine viral diarrhea virus by treatment with adrenocorticotropic hormone

Recent research has shown that cattle that develop mucosal disease (MD) often, if not always, have been persistently infected with bovine viral diarrhea virus (BVDV) since birth. The purpose of the present study was to determine whether MD could be induced by immunosuppression of persistently BVDV-infected cattle. For that purpose, adrenocorticotropic hormone (ACTH) was injected intramuscularly, twice daily for 5 consecutive days in 4 persistently BVDV-infected cattle and in 3 control cattle. Before the ACTH treatment, the numbers of leukocytes, neutrophils and mononuclear cells (MNC) per litre of blood in BVDV-infected cattle were in the same range as in the controls. Similarly, the proportions of B cells, T cells, monocytes and Fcγ⁺ cells (cells with receptor for the Fc part of IgG) were the same in the 2 groups of animals. On the other hand, the proliferative response to mitogen stimulation of MNC obtained from the control animals was twice as high as the corresponding value of the persistently BVDV-infected cattle.In all animals, ACTH treatment caused increased Cortisol concentrations, leukocytosis, neutrophilia and decreased mitogen-induced lymphocyte stimulation. However, the MNC count and the proportions of B cells, T cells, Fcγ⁺ cells and monocytes remained unaltered. In spite of the immunosuppression, indicated by the decrease in mitogen-induced lymphocyte stimulation. ACTH treatment did not provoke any clinical signs of MD in the persistently BVDV-infected cattle.     

Genetic association between GHSR1a 5′UTR‐microsatellite and nt‐7(C>A) loci and growth and carcass traits in Japanese Black cattle

We carried out a genetic association study between five nucleotide polymorphisms (5′UTR microsatellite ((TG)_n), nt‐7(C>A), L24V, DelR242 and Intron 1 microsatellite) of the GHSR1a gene and growth and carcass traits in 1285 steers sired by 117 Japanese Black bulls in a progeny testing program. We report herein, a significant association between the 5′UTR microsatellite and nt‐7(C>A) loci and growth and carcass traits. We also propose a translational hypothesis that the association is due to differences in the secondary structure of GHSR1b mRNA (the non‐spliced type with the 5′UTR microsatellite) among the GHSR1a gene haplotypes. Furthermore, we predicted the potential increase in profitability due to increased carcass weight in cow‐calf fattening enterprises through planned matings based on DNA testing of the 5′UTR microsatellite. Statistical analysis revealed that the 5′UTR microsatellite locus had a significant additive effect on carcass weight (CW) and average daily gain (ADG), but not on beef marbling score (BMS). One of the four major microsatellite alleles (19‐TG allele) with an allele frequency of 0.145, had a significantly (P < 0.0007) desirable effect on CW and ADG. We concluded that the 19‐TG allele could potentially be economically useful nucleotide markers for growth and carcass traits in Japanese Black cattle.     

Survey on vertical infection of bovine viral diarrhea virus from fetal bovine sera in the field

Bovine viral diarrhea virus (BVDV) isolation and antibody survey were performed using 2,758 fetal bovine sera (FBS) collected from slaughterhouses in New Zealand, Australia and the Dominican Republic, and then sent to Japan to manufacture commercial serum for cell culture use. FBS in the Dominican Republic were pooled for each several individuals, and those collected in other countries were separated according to each individual and subjected to the tests. BVDV was isolated from 25 (0.91%) FBS, and the BVDV antibody was detected in 44 (1.60%) FBS. The survey on 139 sets of paired sera of a dam and her fetus revealed that neither the BVDV antibody nor BVDV was detected in all FBS from BVDV antibody-positive dams.     

Endemic infections of bovine viral diarrhea virus genotypes 1b and 2a isolated from cattle in Japan between 2014 and 2020

Bovine viral diarrhea virus (BVDV) is a causative agent of bovine viral diarrhea. In Japan, a previous study reported that subgenotype 1b viruses were predominant until 2014. Because there is little information regarding the recent epidemiological status of BVDV circulating in Japan, we performed genetic characterization of 909 BVDV isolates obtained between 2014 and 2020. We found that 657 and 252 isolates were classified as BVDV-1 and BVDV-2, respectively, and that they were further subdivided into 1a (35 isolates, 3.9%), 1b (588, 64.7%), 1c (34, 3.7%), and 2a (252, 27.7%). Phylogenetic analysis using entire E2 coding sequence revealed that a major domestic cluster in Japan among BVDV-1b and 2a viruses were unchanged from a previous study conducted from 2006 to 2014. These results provide updated information concerning the epidemic strain of BVDV in Japan, which would be helpful for appropriate vaccine selection.