Interactions of bovine and caprine herpesviruses with the natural and the foreign hosts.

Bovine herpesvirus 1 (BHV1) and caprine herpesvirus 1 (CapHV1) are useful models to study virus-host interactions, as well as pathogenicity and latency, when comparing the outcome of infection in the natural and the foreign hosts. Molecular seroepidemiological analyses revealed that cross-reacting antibodies were mainly induced by glycoprotein gI (gB analogue), by the major capsid protein and by nonstructural proteins, whereas the most virus-specific antibodies were elicited by glycoproteins gIII and gIV. These glycoproteins, especially gIII (gC analogue), might therefore play an important role in the virus-host-interactions. As a basis for further studies, we re-evaluated observations concerning experimental infections with BHV1 and CapHV1 in the natural and the foreign hosts. All parameters indicated that both viruses were able to infect either host, but that the pathogenicity was restricted to the natural host. Latent virus could be reactivated exclusively from cows infected with BHV1. It was possible neither to reactivate BHV1 from goats, nor to reactivate CapHV1 from either species. The experiments indicated that the outcome of infection in the natural and the foreign host is dependent on host and viral factors, whereby gIII is only one important virus component involved. Further investigations in the host and host cell range of BHV1 and CapHV1 will help to clarify the role of factors responsible for virus-host-interactions.

A casual finding of primary splenic Hodgkin's disease in a case of traumatic rupture of the spleen.

A case of 15-year-old male with traumatic rupture of the spleen is reported. Patterns of Hodgkin's lymphoma were found in sections of the spleen. Lymph nodes were not involved. Ten years after the splenectomy the patient is alive and well.

Reduction of the number of mice used for potency testing of human and animal rabies vaccines.

Eight different rabies vaccines were tested for their potency in the standard mouse potency test using 3-, 5- and 7-week-old mice. 5-week-old mice seem to be best suited for this purpose, variability from test to test could be reduced considerably. An ELISA was used in parallel for the evaluation of the rabies glycoprotein content of rabies vaccines. Results of the mouse potency test correlated well with those of the ELISA if highly purified human vaccines were tested. Unspecific reactions in the ELISA caused by adjuvanted veterinary vaccines could not be blocked. Further experiments will be needed in order to evaluate the potency of inactivated veterinary rabies vaccines by a in vitro test.

[Potency testing of veterinary vaccines, rabies vaccines as an example]

Vaccines which are produced commercially should be controlled with respect to their efficacy (potency) and their "harmlessness" to the recipient animal. The basis for any potency test is the protection test in the target animal species. When a vaccine has been shown to be capable of protecting a particular species from a certain disease, alternative methods for potency testing often can be developed. The justification of the latter is that experiments which analyze the protection are cost-intensive, require a large number of animals and give only a moderate degree of reproducibility. Methods such as protection experiments in laboratory animals, the induction of the substances responsible for protection (such as antibodies) in target or laboratory animals as well as with in vitro tissue culture systems, or the quantitative determination of the immunogens (the components of a vaccine which should be responsible for protection) may be used only if their results correlate with those obtained from protection experiments in the target animal species. Rabies glycoprotein has been implicated as the main agent responsible for the induction of protection against rabies. The higher the content of glycoprotein in a rabies vaccine, the greater will be the potential of the vaccine to induce protection against the disease. Analyses of the rabies glycoprotein content in vaccines can make use of a number of methods which have proven acceptable (the immunodiffusion test, the antibody binding assay and the ELISA). However, in veterinary medicine most vaccines are associated with an adjuvant - a substance which should amplify the immune response of an animal against a vaccine. Since the adjuvants and vaccines in such preparations are inseparable, the presence of an adjuvant in a vaccine reduces the applicability of many in vitro methods. Thus, the above mentioned methods and possibilities for their adaptation to the analysis of adjuvanted vaccines will be discussed.