Rhipicephalus appendiculatus serpin-3 (RAS-3), R. appendiculatus serpin-4 (RAS-4) and a 36kDa immuno-dominant protein of R. appendiculatus (RIM36) were reported as candidate antigens for the anti-tick vaccine to control ixodid ticks. In the present study, we generated recombinant proteins of RAS-3 (rRAS-3), RAS-4 (rRAS-4) and RIM36 (rRIM36), and assessed their potency as an anti-tick cocktail vaccine in cattle model. RT-PCR analysis showed that RAS-3, RAS-4 and RIM136 transcripts were detected in both adult male and female ticks during feeding. Immunization of cattle with the combination of rRAS-3, rRAS-4 and rRIM36 had raised antibodies against all recombinants and anti-sera had reacted with the molecules from the tick salivary gland extract. Tick infestation challenge demonstrated protective immunity against female ticks, resulting in mortality rates of 39.5 and 12.8 % for the vaccinated and control groups, respectively. Moreover, the mortality rate of Theileria parva-infected female ticks was 48.5 and 10.8 % in the vaccinated and control group, respectively. In order to evaluate the levels of pathogen transmission capacity by T. parva-infected ticks fed on immunized cattle, the occurrence of T. parva in the bovine parotid lymph node and peripheral blood was also determined and quantified by real-time PCR. Although the infection with T. parva could not be protected by the vaccine, the occurrence of pathogen in peripheral blood was delayed 1 to 2 days after the infestation challenge in vaccinated group. These results suggest that this cocktail vaccine plays a role in the prevention of tick infestation.

In their quest for a blood meal, hematophagous arthropods must first defeat the host's hemostatic defense. Following injury as it occurs when hematophagous arthropods insert their proboscis into host skin to feed, the host will attempt to stop excessive blood loss through its hemostatic defense mechanism involving platelet aggregation, blood clotting and vasoconstriction. To acquire a full blood meal hematophagous arthropods inject an arsenal of bioactive enzymes which ultimately overpower the host's hemostatic defense. We have looked at a selected number of studies on the molecular biology of arthropod anti-hemostatic proteins and developed commentaries on the suitability of these molecules as target tick vaccine antigens.

Test vaccines comprised of inactivated water-in-oil emulsions containing various antigen levels were prepared using a non-pathogenic H5N1 avian influenza (AI) virus, A/duck/Hokkaido/Vac-1/04 (H5N1). The potencies of these test vaccines were evaluated by two experiments. In the first experiment, the triangular relationship among the antigen levels of test vaccines, the hemagglutination inhibition (HI) antibody response, and the protective effect against challenge with a highly pathogenic avian influenza (HPAI) virus, A/chicken/Yamaguchi/7/04 (H5N1), was confirmed. Then lasting immunity of chickens after a single-shot vaccination was confirmed in the second experiment. As a result, complete protection after the challenge was observed in chickens immunized by test vaccines with an antigen level of 160 HA units/dose or higher. Thus, it was ascertained that the minimum antigen level in the AI vaccine was 160 HA units/dose, and the minimum HI antibody titer that could protect chickens from HPAI virus infection-related death was considered to be 1:16. Dose-dependent HI antibody responses were observed in chickens after the vaccination. Thus, 640 HA units/dose were thought to be similar to the optimal antigen level. Alternatively, the HI antibody titers of chickens, injected with the vaccine containing 640 HA units/dose, were maintained at 1:181 or higher for 100 weeks after the single-shot vaccination.

To establish vaccine strains of H5 and H7 influenza viruses, A/duck/Hokkaido/Vac-1/04 (H5N1) [Vac-1/04 (H5N1)], A/duck/Hokhaido/Vac-3/07 (H5N1) [Vac-3/07 (H5N1)], and A/duck/Hokkaido/Vac-2/04 (H7N7) [Vac-2/04 (H7N7)] were generated from non-pathogenic avian influenza viruses isolated from migratory ducks. Vac-1/04 (H5N1) and Vac-3/07 (H5N1) were generated by genetic reassortment between H5N2 or H5N3 virus as an HA gene provider and H7N1 or H6N1 virus as an NA gene provider. Vac-2/04 (H7N7) was a genetic reassortant obtained using H7N7 and H9N2 viruses to give high growth character of the H9N2 virus in chicken embryonated eggs. The results of sequence analyses and experimental infections revealed that these H5N1 and H7N7 reassortant viruses were non-pathogenic in chickens and embryos, and had good growth potential in embryonated eggs. These viruses should be useful to develop vaccines against H5 and H7 highly pathogenic avian influenza viruses.

Puumala virus (PUUV), a causative agent of hemorrhagic fever with renal syndrome (HFRS), is prevalent in Europe and European Russia. No vaccine has been developed for PUUV-associated HFRS, primarily because of the low viral yield in cultured cells. A PUUV strain known as DTK/Ufa-97 was isolated in Russia and adapted for growth in Vero E6 cells maintained in serum-free medium. The DTK/Ufa-97 strain produced a higher viral titer in serum-free medium, suggesting that it may prove useful in the development of an HFRS vaccine. When PUUV-infected Vero E6 cells were grown in serum-free medium, the DTK/Ufa-97 strain yielded more copies of intracellular viral RNA and a higher viral titer in the culture fluid than did the Sotkamo strain. Phylogenetic analysis revealed that PUUVs can be classified into multiple lineages according to geographical origin, and that the DTK/Ufa-97 strain is a member of the Bashkiria-Saratov lineage. The deduced amino acid sequences of the small, medium, and large segments of the DTK/Ufa-97 strain were 99.2% to 100%, 99.3% to 99.8%, and 99.8% identical, respectively, to those of the Bashkirian PUUV strains and 96.9%, 92.6%, and 97.4% identical, respectively, to those of the Sotkamo strain, indicating that the PUUVs are genetically diverse. However, DTK/Ufa-97 and other strains of PUUV exhibited similar patterns of binding to a panel of monoclonal antibodies against Hantaan virus. In addition, diluted antisera (i.e., ranging from 1:160 to 1:640) specific to three strains of PUUV neutralized both homologous and heterologous viruses. These results suggest that the DTK/Ufa-97 strain is capable of extensive growth and is antigenically similar to genetically distant strains of PUUV.