Detection of BHV-1 in a Naturally Infected Bovine Fetus by a Nested PCR assay

Bovine herpesvirus 1 (BHV-1) is frequently associated with abortion in naturally and experimentally infected cattle. Most of the virus isolation and immunofluorescent antibody protocols described in the literature for detecting BHV-1 in bovine foetuses are rather laborious, costly and time-consuming. The detection is described of BHV-1 in the tissues of a naturally aborted bovine foetus by a nested PCR assay with no further hybridization procedures.Optimal results were achieved by filtering the foetal tissues on a chromatography column before DNA extraction, by using two pairs of primers in a nested PCR and by evaluating the amplification products on silver-stained polyacrylamide gels.This nested PCR was faster and easier to perform than the virus isolation test. To our knowledge, this is the first time that BHV-1 has been detected in the tissues of a naturally infected bovine foetus by means of a nested PCR. The test seems to be a practical alternative for rapid detection of BHV-1 in bovine foetus.     

Efficacy of a quadrivalent vaccine against respiratory diseases caused by BHV-1, PI3V, BVDV and BRSV in experimentally infected calves

The efficacy of a quadrivalent vaccine against viral bovine respiratory diseases (BRD) was assessed in four experimental studies. Calves between 2 and 9 months of age were allocated to one of two treatment groups (n=9-15) and then received either the vaccine or sterile saline in two doses approximately 3 weeks apart. Three to 5 weeks after the second injection, animals were challenged experimentally with one of the viruses, bovine herpes-virus-1 (BHV-1), parainfluenza type-3 virus (PI(3)V), bovine viral-diarrhoea virus type 1 (BVDV), or bovine respiratory syncytial virus (BRSV) and were then monitored for at least 2 weeks. The administration of the vaccine was associated with enhanced antibody response to all four viruses post-challenge, with the reduction of the amount or duration (or both) of virus shedding in the BHV-1, PI(3)V, BVDV and BRSV studies and with an improvement of some clinical signs in the BHV-1 (nasal discharge, and rectal temperature) and the PI(3)V studies (abnormal respiration, and depression).     

The food contaminant fumonisin B1 reduces the maturation of porcine CD11R1+ intestinal antigen presenting cells and antigen-specific immune responses, leading to a prolonged intestinal ETEC infection

Consumption of food or feed contaminated with fumonisin B₁ (FB₁), a mycotoxin produced by Fusarium verticillioides, can lead to disease in humans and animals. The present study was conducted to examine the effect of FB₁ intake on the intestinal immune system. Piglets were used as a target and as a model species for humans since their gastro-intestinal tract is very similar. The animals were orally exposed to a low dose of FB₁ (1 mg/kg body weight FB₁) for 10 days which did not result in clinical signs. However, when compared to non-exposed animals, FB₁-exposed animals showed a longer shedding of F4⁺ enterotoxigenic Escherichia coli (ETEC) following infection and a lower induction of the antigen-specific immune response following oral immunization. Further analyses to elucidate the mechanisms behind these observations revealed a reduced intestinal expression of IL-12p40, an impaired function of intestinal antigen presenting cells (APC), with decreased upregulation of Major Histocompatibility Complex Class II molecule (MHC-II) and reduced T cell stimulatory capacity upon stimulation. Taken together, these results indicate an FB₁-mediated reduction of in vivo APC maturation.     

Protective immune responses induced by in ovo immunization with recombinant adenoviruses expressing spike (S1) glycoprotein of infectious bronchitis virus fused/co-administered with granulocyte-macrophage colony stimulating factor

Infectious bronchitis virus (IBV) causes tremendous economic losses associated with production inefficiencies and mortality in poultry industry worldwide. In the present report, the recombinant adenoviruses expressing chicken granulocyte-macrophage colony stimulating factor (GM-CSF) and S1 gene of nephropathogenic IBV were constructed and characterized. Then, the immunological efficacy and protection against homologous IBV challenge were assessed in specific pathogen free (SPF) chickens. The results showed that the chickens vaccinated in ovo with rAd-S1, rAd-GM-S1 (GM-CSF fused with S1 using glycine linkers) and rAd-GM-CSF plus rAd-S1 (co-administered) developed specific anti-IBV HI antibodies. Moreover, the fusion of the GM-CSF markedly increased spleen cell proliferation and IFN-γ production while mild increased in IL-4 production, which demonstrated the enhancement of cell-mediated immune responses. Following challenge with IBV, the chickens in the group vaccinated with rAd-S1 fused or co-administered with GM-CSF had fewer nephropathic lesions and showed 100% protection as compared to that of rAd-S1 alone which showed 70% protection. It indicated that the single dose in ovo vaccination of the GM-CSF fused or co-administered with S1 of IBV could enhance significantly the humoral, cellular immune responses and provide complete protection against nephropathogenic IBV challenge. This finding may provide basic information for effective in ovo vaccines design against IBV.