Characterization of experimental equine glanders.

Considerable advances in understanding of the disease caused by Burkholderia mallei have been made employing a combination of tools including genetic techniques and animal infection models. The development of small animal models has allowed us to assess the role of a number of putative virulence determinants in the pathogenesis of disease due to B. mallei. Due to the difficulties in performing active immunization studies in small animals, and due to the fact that the horse is the target mammalian species for glanders, we have initiated experimental studies on glanders in horses. Intratracheal deposition of B. mallei produced clinical glanders with organisms being recovered from tissues of infected horses. The model should prove to be of considerable value in our ongoing studies on the pathogenesis and vaccine development for glanders.

Use of a Japanese quail fibrosarcoma cell line (QT-35) in serologic assays to determine the antigenic relationship of avian metapneumoviruses.

The ability of a Japanese quail fibrosarcoma cell line (QT-35) to support the replication of avian metapneumoviruses belonging to the 3 subgroups A (14/1 virus), B (Colorado virus), and C (Hungary virus) enabled the development of assays for the detection and evaluation of virus-specific antibodies. On the basis of the results of enzyme-linked immunosorbent assay (ELISA), plaque reduction neutralization assay (PRNA), immunofluorescent assay (IFA), and Western blot analysis, some degree of antigenic cross-reactivity was observed between prototype viruses belonging to each of the 3 subgroups A, B, and C. The antigen produced in QT-35 cells was found to be superior with respect to its reactivity with virus-specific antibodies, as determined when used in ELISA and IFA. Standardization of both the input virus and the virus-specific antibodies in PRNA enabled a more detailed analysis of the antigenic relationship between these viruses. Specifically, it was observed that 14/1 virus shared more neutralizing regions with Hungary and Colorado viruses than did either of these viruses with 14/1 virus. In addition, Hungary virus shared comparatively fewer neutralizing epitopes with the Colorado virus than did 14/1 virus. Western blot analysis of the reactivity patterns of virus antigen, produced in QT-35 cells, with subgroup-specific antibodies identified a cross-reactive protein migrating at approximately 18 kD. These assays and the information from the Western blot will enable further analysis of avian metapneumovirus isolates to determine antigenic relationships.