Detection of antibodies to equine arteritis virus in horse sera using recombinant chimaeric N/G(L) protein

Production of Recombinant N Protein of Infectious Bronchitis Virus Using the Baculovirus Expression System and Its Assessment as a Diagnostic Antigen

The avian coronavirus-infectious bronchitis virus (AvCoV-IBV) is recognized as an important avian pathogen, and new viral variants are a continuous threat to the poultry industry worldwide. Sensitive diagnostics and efficacious vaccines are necessary to combat IBV infections in chickens. The aim of this study was to produce recombinant N protein of IBV in the baculovirus system to use in ELISA diagnostic tests in order to enable the assessment of the sero-prevalence and risk of IBV infections in chickens in Turkey. For this, the gene encoding the N protein of the Beaudette strain of IBV was expressed using a recombinant baculovirus expression system. The recombinant N protein was purified using Ni-NTA affinity chromatography. An estimated 50-kDa recombinant protein corresponding to the expected molecular weight of IBV N including the 6xHis tag was detected using an anti-His monoclonal antibody. Specific immunoreactivity of the recombinant protein was confirmed by Western blot using antiserum obtained from vaccinated and naturally infected chicken from Turkey as well as using a monoclonal antibody raised against the N protein of the IBV Massachusetts strain. The results obtained with the in-house ELISA had high agreement with a commercial ELISA. Immunoreactivity analysis using antisera in Western blotting and the in-house ELISA suggests that the recombinant IBV N protein could be broadly cross-reactive with antisera produced against different IBV strains. We conclude that the recombinant baculovirus expressed IBV N protein could serve as a useful diagnostic antigen for detection of IBV infections in chickens by ELISA.

Evaluation of two enzyme-linked immunosorbent assays for the detection of antibodies against equine arteritis virus

In order to establish an efficient system for serological diagnosis of equine viral arteritis in Japan, we compared enzyme-linked immunosorbent assays (ELISAs) provided by two manufacturers (Nisseiken Co., Ltd., Tokyo, Japan, and VMRD Inc., Pullman, WA, U.S.A.) by testing a series of horse sera. The results revealed that 159 of 160 virus-neutralizing (VN) antibody-positive serum samples were positive in both the Nisseiken-ELISA and VMRD-ELISA. Of the VN-negative sera (n=157), 134 and 154 samples were negative in the Nisseiken-ELISA and VMRD-ELISA, respectively. Sensitivity was 99.4% for both the Nisseiken-ELISA and VMRD-ELISA. The specificity of the VMRD-ELISA (98.1%) was significantly higher than that of the Nisseiken-ELISA (85.4%, P<0.05). The diagnostic performance of the VMRD-ELISA was superior to that of the Nisseiken-ELISA because of this greater specificity.

Aborted fetal sizes of Thoroughbred horses in Hidaka, Japan, between 2005 and 2015

The degree of fetal growth restriction has been unclear in equine reproduction. In this study, 2,195 fetuses from 2,137 abortions during 11 seasons were examined to determine the causes of abortion, and fetal size dimensions (crown rump length and body weight) were measured. In total, 900 cases (42.1%) of abortion were identified as caused by viral infection (215, 10.1%), bacterial infection (156, 7.3%), fungal infection (25, 1.2%), circulation failure (406, 19.0%), multiple causes (66, 3.1%), deformity (13, 0.6%), placental abnormality (12, 0.6%), and other causes (7, 0.3%). All viral infections originated from equine herpes virus. Of all abortions, 94.3% occurred between 181–360 days of pregnancy, and the gestational ages at abortion were different based on the causes. Fetal sizes in viral abortions were considerably larger than those due to other reasons. Compared with viral infection, the crown rump length size dimension of fetuses aborted from multiple and fungal infection was affected. In addition, bacterial infection, circulation failure, and unknown causes of abortions also contributed to growth restriction in terms of body weight. In conclusion, the present study showed details of equine abortion and the relationships between causes of abortion and fetal size. Most of the aborted fetuses showed restrictions in their growth. The manifestations of growth restriction were more related to weight than skeletal length.