Serological response in cattle immunized with inactivated oil and Algel adjuvant vaccines against infectious bovine rhinotracheitis.

Infectious bovine rhinotracheitis (IBR) virus was grown in Madin Darby bovine kidney (MDBK) cell line using a roller culture system for its large-scale production. Optimum multiplicity of infection (MOI) of 1:750 was found to give consistent virus yield. To determine the appropriate payload, three batches of antigen with virus titres ranging from 10(8.37) to 10(6.37) TCID50 per ml were used to prepare experimental inactivated IBR oil adjuvant vaccine. Beta-propiolactone (BPL) was used as inactivant. The vaccine formulation using inactivated BHV-1 virus antigen with a pre-inactivation titer of 10(8.37) TCID50 per dose elicited better sero-conversion in cattle calves as evidenced from the mean log SN titre of 1.02. To choose the appropriate adjuvant, two batches of vaccine each containing aluminum hydroxide gel (Algel) and Montanide oil respectively were tested in calves. Two groups of 16 calves each were inoculated with Algel and oil adjuvant vaccine respectively twice at four weeks to test the immunogenicity. Adequate titres of vaccine induced anti BHV-1 antibodies could be demonstrated both by ELISA and MNT up to 180 days post vaccination in both the groups.

Clonotype selection and composition of human CD8 T cells specific for persistent herpes viruses varies with differentiation but is stable over time.

Protection from reactivation of persistent herpes virus infection is mediated by Ag-specific CD8 T cell responses, which are highly regulated by still poorly understood mechanisms. In this study, we analyzed differentiation and clonotypic dynamics of EBV- and CMV-specific T cells from healthy adults. Although these T lymphocytes included all subsets, from early-differentiated (EM/CD28(pos)) to late-differentiated (EMRA/CD28(neg)) stages, they varied in the sizes/proportions of these subsets. In-depth clonal composition analyses revealed TCR repertoires, which were highly restricted for CMV- and relatively diverse for EBV-specific cells. Virtually all virus-specific clonotypes identified in the EMRA/CD28(neg) subset were also found within the pool of less differentiated "memory" cells. However, striking differences in the patterns of dominance were observed among these subsets, because some clonotypes were selected with differentiation while others were not. Late-differentiated CMV-specific clonotypes were mostly characterized by TCR with lower dependency on CD8 coreceptor interaction. Yet all clonotypes displayed similar functional avidities, suggesting a compensatory role of CD8 in the clonotypes of lower TCR avidity. Importantly, clonotype selection and composition of each virus-specific subset upon differentiation was highly preserved over time, with the presence of the same dominant clonotypes at specific differentiation stages within a period of 4 years. Remarkably, clonotypic distribution was stable not only in late-differentiated but also in less-differentiated T cell subsets. Thus, T cell clonotypes segregate with differentiation, but the clonal composition once established is kept constant for at least several years. These findings reveal novel features of the highly sophisticated control of steady state protective T cell activity in healthy adults.

Sheep-associated malignant catarrhal fever virus: prospects for vaccine development.

Sheep-associated malignant catarrhal fever is emerging as a significant problem for several ruminant species worldwide. The inability to propagate the causative agent, ovine herpesvirus 2, in vitro has seriously hindered research efforts in the development of effective programs for control of the disease in clinically susceptible hosts. Recent molecular technologic advances have provided powerful tools for investigating this difficult-to-study virus. Identification of the infectious virus source, establishment of experimental animal models and completion of sequencing the genome for ovine herpesvirus 2 have put us in a position to pursue the development of vaccines for control of the disease. In this review, the authors briefly describe the current understanding of ovine herpesvirus 2 and prospectively discuss vaccine development against the virus.