Variations in the viral genome and biological properties of bovine leukemia virus wild-type strains.

Bovine leukemia virus (BLV) is the etiological agent of enzootic bovine leukosis (EBL), which causes enormous economic losses in the livestock industry worldwide. To reduce the economic loss caused by BLV infection, it is important to clarify the characters associated with BLV transmissibility and pathogenesis in cattle. In this study, we focused on viral characters and examined spontaneous mutations in the virus and viral properties by analyses of whole genome sequences and BLV molecular clones derived from cows with and without EBL. Genomic analysis indicated that all 28 strains harbored limited genetic variations but no deletion mutations that allowed classification into three groups (A, B, and C), except for one strain. Some nucleotide/amino acid substitutions were specific to a particular group. On the other hand, these genetic variations were not associated with the host bovine leukocyte antigen-DRB3 allele, which is known to be related to BLV pathogenesis. The viral replication activity in vitro was high, moderate, and low in groups A, B, and C, respectively. In addition, the proviral load, which is related to BLV transmissibility and pathogenesis, was high in cows infected with group A strains and low in those infected with group B/C strains. Therefore, these results suggest that limited genetic variations could affect viral properties relating to BLV transmissibility and pathogenesis.

Lunar Cycle Influences Spontaneous Delivery in Cows.

There is a popular belief that the lunar cycle influences spontaneous delivery in both humans and cattle. To assess this relationship, we investigated the synodic distribution of spontaneous deliveries in domestic Holstein cows. We used retrospective data from 428 spontaneous, full-term deliveries within a three-year period derived from the calving records of a private farm in Hokkaido, Japan. Spontaneous birth frequency increased uniformly from the new moon to the full moon phase and decreased until the waning crescent phase. There was a statistically significant peak between the waxing gibbous and full moon phases compared with those between the last quarter and the waning crescent. These changes were clearly observed in deliveries among multiparous cows, whereas they were not evident in deliveries among nulliparous cows. These data suggest the utility of dairy cows as models for bio-meteorological studies, and indicate that monitoring lunar phases may facilitate comprehensive understanding of parturition.

Changes in leukocyte populations of cows with milk fever or displaced abomasum after calving.

Most of the metabolic diseases of dairy cows occur within the first 2 wk after calving, and cows with a metabolic disease are prone to infectious diseases. Although metabolic diseases are generally recognized as a risk factor for infectious diseases owing to the associated decrease in immune function, the difference in immune status between cows with milk fever (MF) or displaced abomasum (DA) during the lactation period has not been clarified. Therefore, the peripheral blood leukocyte populations in 38 multiparous Holstein cows from 1 herd were analyzed after calving. The cows were divided into 3 groups according to health: 21 cows that remained clinically healthy throughout the experimental period (control group), 9 cows that had MF on the day of calving, and 8 cows with an onset of DA within 4 wk after calving. The T- and B-cell numbers were lowest at week 0, and they increased gradually after calving. There was no significant difference between the 3 groups in the number of each subset of leukocytes on the day of calving, but the number of CD8⁺ T-cells was significantly lower in the MF and DA groups than in the control group at week 1. The numbers of CD4⁺, CD8⁺, and WC1⁺ T-cells tended to be lower in the DA group than in control group from weeks 4 to 12, a tendency not observed in the MF group. These data suggest that when cows have DA around the time of calving, their lymphocyte numbers remain lower until 12 wk after calving.

La plupart des maladies métaboliques des vaches laitières se produisent à l'intérieur des 2 premières semaines après le vêlage, et les vaches avec une maladie métabolique sont sujettes aux maladies infectieuses. Bien que les maladies métaboliques soient généralement reconnues comme un facteur de risque pour les maladies infectieuses à cause de la diminution de la fonction immunitaire qui y est associée, la différence dans le statut immunitaire entre des vaches avec une fièvre du lait (MF) ou un déplacement de caillette (DA) durant la période de lactation n'a pas été clarifiée. Ainsi, les populations des leucocytes du sang périphérique de 38 vaches Holstein multipares provenant de un troupeau ont été analysées après le vêlage. Les vaches ont été divisées en trois groupes selon leur état de santé : 21 vaches qui sont demeurées cliniquement saines durant toute la durée de la période expérimentale (groupe témoin), 9 vaches qui ont eu une MF le jour du vêlage, et 8 vaches avec un début de DA dans les 4 sem après le vêlage. Le nombre de cellules T et B étaient à son plus bas la semaine 0, et il a augmenté graduellement après le vêlage. Il n'y avait pas de différence significative entre les trois groupes dans le nombre de chaque sous-groupe de leucocytes le jour du vêlage, mais le nombre de cellules T CD8+ était significativement plus faible dans les groupes MF et DA que dans le groupe témoin à la semaine 1. Le nombre de cellules T CD4+, CD8+ et WC1+ avaient tendance à être plus faible dans le groupe DA que dans le groupe témoin à partir de la semaine 4 jusqu'à la semaine 12, une tendance non observée dans le groupe MF. Ces données suggèrent que lorsque les vaches ont un DA durant la période du vêlage, leurs dénombrements lymphocytaires demeurent faibles jusqu'à 12 sem après la mise-bas.(Traduit par Docteur Serge Messier).

Hormonal differences in peripheral blood and gene profiling in the liver and lymphocytes in Japanese black cattle with growth retardation.

Japanese Black cattle occasionally demonstrate growth retardation despite sufficient nutrient intake. To clarify hormonal and transcriptional characteristics, we investigated differences in blood components, including hormones, and differences in exhaustive gene expressions in the liver and peripheral lymphocytes of six cattle with growth retardation (GR cattle) and eight control cattle of the same age and pedigree with normal growth. Hematocrit values and concentrations of hemoglobin, serum albumin, total cholesterol, insulin-like growth factor 1 (IGF-1), thyroxine and insulin in GR cattle were significantly lower than those in controls. GR cattle also excreted higher levels of GH. We used three GR and three control cattle for a microarray analysis in the liver and found that 279 gene expressions were significantly different. However, gene expressions related to the GH-IGF-1 axis, such as the GH receptor and IGF-1, were not significantly different from those of controls. Immune-related gene expressions were significantly lower. To clarify these gene expression levels, peripheral lymphocytes were used for real-time RT-PCR. The expression rates of genes that were significantly lower in the liver, such as chemokine ligand 8, interferon gamma receptor 1 and immunoglobulin light chain VJ region were also significantly lower in three GR cattle than those in the three control cattle. These results suggest that the cause of growth retardation in the present study was due to other factors, not abnormal gene expressions of factors related to the GH-IGF-1 axis in the liver, and that GR cattle were susceptible to infectious disease.

Effect of progesterone on Th1/Th2/Th17 and regulatory T cell-related genes in peripheral blood mononuclear cells during pregnancy in cows.

T helper (Th) cells play a central role in immune responses and new Th1/Th2/Th17 and regulatory T (Treg)-cell paradigm in pregnancy has developed. Progesterone (P(4)) is essential for the maintenance of pregnancy; however the effect of P(4) on Th1/Th2/Th17 and Treg paradigm is unclear in cows. We evaluated the effect of P(4) on the expression of Th1/Th2/Th17 and Treg-related cytokines, transcription factors, and P(4) receptors in the peripheral blood mononuclear cells (PBMCs) from 8 pregnant (163.1 ± 16.9 days of gestation) and 8 non-pregnant luteal phase cows. PBMCs were stimulated with P(4) at 0, 0.1, 1 or 10 µg/ml, and the mRNA expression of Th1, Th2, Th17 and Treg-related cytokines (IFN-γ, IL-4, IL-17 and TGF-ß), transcription factors (T-bet, GATA-3, RORC and Foxp3) and P(4) receptors (PGR, PGRMC1 and PGRMC2) were analyzed by real time RT-PCR. In both pregnant and non-pregnant cows, P(4) significantly inhibited the expression of IFN-γ and IL-17 dose-dependently, whereas P(4) did not affect the expression of TGF-ß and Foxp3. In addition, P(4) significantly decreased the expression of T-bet and RORC, and enhanced the expression of IL-4 in the pregnant cows, but this reaction was not found in the non-pregnant cows. P(4) tended to increase PGRMC1 in the pregnant cows but not in the non-pregnant cows, indicating that PGRMC1 may be involved in the regulation of the effect of P(4) during bovine pregnancy. These results indicate that P(4) is an important regulator of Th1/Th2/Th17 and Treg immunity, and higher Th2 immunity is characteristic in the pregnant cows.

Effect of progesterone on the in vitro response of peripheral blood mononuclear cells stimulated by Escherichia coli in mares.

Escherichia coli(E. coli) isolated from the uterus of a Thoroughbred mare with bacterial endometritis was used to evaluate the effect of progesterone (P(4)) on the immune response of mares. Peripheral blood mononuclear cells (PBMCs) were collected from 10 nonpregnant clinically healthy adult mares (range, 4-12 years) during diestrus, four Thoroughbreds and six Hokkaido native horses. Cell proliferation and expression of cytokine mRNA, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-10, of PBMCs stimulated with E. coli and P(4) were examined in vitro. P(4) was shown to have significantly inhibited E. coli induced proliferation and expression of IFN-γ in PBMCs. These results indicate that P(4) inhibits the immune response to E. coli in mares.

Healing characteristics of deep digital flexor tenorrhaphy within the digital sheath of horses.

OBJECTIVE: To describe the healing characteristics of deep digital flexor tenorrhaphy within the digital sheath. STUDY DESIGN: Experimental study. ANIMALS: Five mature horses. METHODS: Right thoracic limb, deep digital flexor tenorrhaphy was performed within the digital sheath. Limbs were cast in partial flexion using a short limb cast for 6 weeks. Next, extended heel shoes were used for limb support for 14 weeks. Healing was evaluated by sequential ultrasonographic examinations, and limb use was evaluated by force plate analysis. At 26 weeks, mechanical strength and morphologic characteristics of the repair site were evaluated. RESULTS: Gap (mean, 0.93 cm.) formation was evident in unloaded limbs at 3 weeks. This increased markedly by 6 weeks and was 5 cm at 26 weeks. Demarcation between the deep and superficial flexor tendons decreased as the transected ends adhered to the dorsal surface of the superficial flexor tendon. The intrathecal space was reduced by fibrous tissue. Mean maximum load to failure of the repair tissue was 4,616 +/- 3,556 N, with a mean stress of 12.99 +/- 2.78 MPa. The repair consistently failed at the adhesion between the transected tendon and the superficial flexor tendon. CONCLUSIONS: Intrathecal tenorrhaphy with external coaptation (in partial limb flexion) for 6 weeks resulted in gap healing, fibrous adhesion between the deep and superficial flexor tendons, fibrous tissue reduction of the intrathecal space, and a pasture-sound horse at 26 weeks. CLINICAL RELEVANCE: Without improved methods for immobilizing the deep digital flexor tendon, intrathecal tenorrhaphy is unlikely to result in first intention tendon healing.