Genomic variability among globally distributed isolates of equine arteritis virus.

Equine arteritis virus (EAV), a non-arthropod borne togavirus, has been shown to have a global distribution. To date, no major antigenic variation has been demonstrated between EAV isolates from different geographic origins. In this study, the genomic RNA of EAV isolates obtained from horses of different breeds in various countries around the world was oligonucleotide fingerprinted. Comparisons of these fingerprints were used to determine the extent of genomic variation among such isolates. Comparisons among isolates from North American horses revealed, for the most part, oligonucleotide homologies of less than 60%. Only 29 of the 98 comparisons revealed greater than 60% oligonucleotide homology. Nonetheless, several comparisons indicated a close epidemiologic relationship between isolates from horses of different breeds located in different states. Though all European isolates were of Standardbred origin and were from horses located in northern European countries, the majority had oligonucleotide homologies of less than 60%. Where oligonucleotide homology was apparent, it was, with one exception, greater than 70%. The two isolates from New Zealand had 93.2% oligonucleotide homology. This is indicative of an extremely close epidemiologic relationship. Comparisons between EAV isolates from around the world revealed oligonucleotide homologies between viruses from North America, Europe and New Zealand. In several instances, this homology was greater than 70% and in one case greater than 80%. No oligonucleotide homology was evident in comparisons involving the virus from South Africa. The high level of genomic conservation between certain EAV isolates of disparate geographic origins may reflect dissemination of the virus associated with the international movement of horses. The extent of genomic variation demonstrated between most of the EAV isolates used in this study confirms the need for further investigation of genomic heterogeneity among strains of this virus before techniques that rely upon nucleic acid hybridization can be effectively applied as diagnostic procedures.

[Immunologic response in bursectomized and non-bursectomized chickens inoculated with Newcastle disease virus (NDV) after administration of sheep erythrocytes (SRBC) or bovine serum albumin (BSA)]. / Odpowiedz immunologiczna kurczat bursektomowanych i niebursektomowanych szczepionych wirusem choroby Newcastle (NDV) po podaniu erytrocytów owcy (SRBC) lub albuminy surowicy bydlecej (BSA).

Astra S hybrid chickens, bursectomized within 48 hours of life, were administered the following antigens: virus of Newcastle disease (NDV) in the fourth week of life and sheep red blood cells (SRBC) or bovine serum albumin (BSA) 10-12 days later. Level of antibodies to the antigens was determined in the sixth week of the birds' life. Administration of SRBC to non-bursectomized chickens inoculated with NDV brought about, in comparison with the chickens not administered SRBC, several-time increase in the titre of anti-NDV antibodies, the anti-SRBC antibodies in chickens inoculated and not inoculated with NDV stayed at the same level. Now, administration of BSA to non-bursectomized chickens inoculated with NDV, in comparison with those not stimulated with BSA, brought about a slight decrease in the titre of anti-NDV antibodies. Bursectomized chickens appeared to exhibit much weaker reaction to the three antigens than the non-bursectomized ones. Administration of SRBC to bursectomized chickens inoculated with NDV exerted no influence on the level of anti-NDV antibodies but, in comparison with those not inoculated with NDV, the titre of anti-SRBC antibodies in them increased twice. Inoculation of bursectomized chickens with NDV followed by administration of BSA brought about, in comparison with those not administered BSA, an increase in the titre of anti-NDV antibodies. At the same time bursectomized chickens inoculated with NDV exhibited a lower level of anti-BSA agglutinins in comparison with the not inoculated ones.