Anticancer vaccines.

With the tools of molecular biology and a greater understanding of mechanisms to harness the immune system, effective tumor immunotherapy is becoming a reality. This new class of therapeutics offers a more targeted, and therefore precise, approach to the treatment of cancer. The recent conditional licensure of a xenogeneic DNA vaccine for advanced canine malignant melanoma strongly suggests that immunotherapy can play an extremely important role alongside the classic cancer treatment triad components of surgery, radiation therapy, and chemotherapy.     

Psittacine vaccines.

Vaccines for Pachecho's disease and Psittacine pox are described. Clinical trials of these vaccines are discussed, and vaccination recommendations are included.     

Thermostable Newcastle disease vaccines in Tanzania.

The V4 thermostable Newcastle disease vaccine was tested under village conditions in Central Tanzania. The vaccination regimes were four vaccinations by eye drop (eye drop group), one vaccination by eye drop followed by three vaccinations by drinking water (drinking water group), one vaccination by eye drop followed by three vaccinations with vaccine supplied on boiled sorghum (food vaccine group) and no vaccine (control group). Antibody responses in the eye drop and drinking water groups suggested that at least 70% of the chickens would be protected against challenge with virulent virus. In both groups, eight of the 11 chickens survived laboratory challenge. Only three of the 11 chickens in the food vaccine group resisted challenge, and none of the 10 control chickens.     

Evolution of bovine viral diarrhea virus vaccines.

Control of bovine viral diarrhea virus (BVDV) infection is economically important to the cattle industry because the virus causes a variety of clinical diseases that adversely affect essentially all stages of the production cycle. Production losses primarily stem from reproductive failure and from immunosuppression during acute BVDV infection, which predisposes calves to respiratory or enteric diseases. Control is achieved by implementing herd health pro-grams focused on limiting exposure by avoiding persistently infected (PI) carrier cattle and by optimizing protective immunity through immunization. Vaccination cannot be relied upon solely to protect against fetal infection and losses due to BVD. This is because no single BVDV vaccine has been shown to give complete fetal protection. In addition to strategic use of vaccines, herd management practices should also be implemented to identify and eliminate PI carrier cattle and to avoid exposure to BVDV infection.     

Evaluation of inactivated infectious bovine rhinotracheitis vaccines.

Sixty-five calves of approximately three months of age and of mixed sex were vaccinated twice at four week intervals with either attenuated or inactivated infectious bovine rhinotracheitis vaccines. Following initial vaccination there was no demonstrable serum infectious bovine rhinotracheitis titer in any of the calves receiving the inactivated vaccine with 20.7% of the calves receiving the attenuated vaccines having demonstrable titers. Following a second administration of vaccine at eight weeks post-initial vaccination 63.9% of the calves receiving the inactivated vaccine had no demonstrable titer with 72.4% of the calves receiving the attenuated vaccine exhibiting a blood titer of four or greater.     

Riems foot-and-mouth disease oil emulsion vaccines for swine. 2. Use of foot-and-mouth 2-component oil emulsion vaccines in practice

Riems FMD two-component oil emulsion vaccine was subcutaneously applied (5 ml) under field conditions to 855 store pigs of different age groups (trivalent--O1, A5, C). It produced early onset of lasting strong immunity against the three above FMD virus types. General condition of the animals and their body weight development were not adversely affected. Pea-size to walnut-size vaccination granulomas were recorded on slaughter as locally delimited reactions in 15 to 20 percent of vaccinated animals and were found to be morphologically correlated to adjuvant action. They were easily removed from the carcasses by excision of the vaccination point, with only minor loss of slaughter substance.     

Chlamydial vaccines

With few exceptions, immunity from chlamydiosis availed by current vaccines is limited and can even be detrimental. Possible reasons for failure include immunotype or strain differences, ill-defined virulence variation, presentation of deleterious antigens, and incorrect presentation of critical antigens to the body. Antigens that stimulate neutralizing antibodies active at 2 steps of infection have been identified. A third step, prevention of phagolysosomal fusion, needs to be further studied, and causal antigens need to be identified. A fourth possible stage for antibody participation is in antibody-dependent cell-mediated cytotoxicity. If chlamydial antigens are expressed on the surface of infected cells, this mechanism of destruction of infected cells and the antigens that elicit it will need to be more fully examined. Cell-mediated immune responses participating in eliminating chlamydial infections need to be further clarified. Activated macrophages are the best characterized effector mechanism of cell-mediated immunity thus far, regardless of the stimulatory cytokines involved. It is important to determine how sensitized lymphocytes recognize antigen(s) that cause them to release macrophage-activating cytokines. It must be determined whether chlamydial antigens are expressed on the surface of infected cells and then recognized by potential cytokine-releasing lymphocytes in context with major histocompatibility antigens (surface expression) or whether they are recognized on antigen-presenting cells functioning in more of a scavenging capacity. Membrane expression of antigen is also important in that it also defines whether cytotoxic T cells and antibody-dependent cell-mediated cytotoxicity have roles in resistance to chlamydial infection. Also, it is important to realize the possible limitation of these mechanisms to systemic sites of the body. If membrane expression does occur, it must be determined how it functions at mucosal sites, whether it occurs at the luminal surface of mucosal epithelial cells only, or whether there is expression of antigens at abluminal membrane surfaces perhaps more accessible to such immune effector mechanisms. Delivery of critical antigens to the individual is the final component in establishing effective vaccines. Carrier systems capable of stimulating long-lasting mucosal and systemic immunity are available and need to be further studied as protective immunogens become available.     

Further development of P. multocida vaccines for swine

149 strains with antigen fractions of both A and D type could be found out of 446 P. multocida field strains of porcine origin. Most of them are producing the dermonecrotizing toxin. These A/D strains proved to be virulent in mice and piglets as well. In mice, the vaccination with one of the most virulent and immunogenic A/D strains, inactivated and A1(OH)3 adsorbed caused an immunity against challenge infections with P. multocida of types A, D and A/D. This effect could be confirmed on SPF piglets.