Comparative Evaluation of T-Cell Immune Response to BTV Infection in Sheep Vaccinated with Pentavalent BTV Vaccine When Compared to Un-Vaccinated Animals.

Molalegne Bitew,Gaurav Kumar Sharma,Sukdeb Nandi,Chintu Ravishankar,Soumendu Chakravarti

doi:10.1155/2019/8762780

Molalegne Bitew, Gaurav Kumar Sharma + Show 3 more

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https://doi.org/10.1155/2019/8762780

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Abstract

Recent invasion of multiple bluetongue virus serotypes (BTV) in different regions of the world necessitates urgent development of efficient vaccine that is directed against multiple BTV serotypes. In this experimental study, cell mediated immune response and protective efficacy of binary ethylenimine (BEI) inactivated Montanide™ ISA 206 adjuvanted pentavalent (BTV-1, 2, 10, 16 and 23) vaccine was evaluated in sheep and direct challenge with homologous BTV serotypes in their respective group. Significant (P < 0.05) up-regulation of mRNA transcripts of IFN-α, IL-2, IL-6, IL-12, IFN-γ and TNF-α in PBMCs of vaccinated animals as compared to control (un-vaccinated) animals at certain time points was observed. On the other hand, there was a significant increase in mean ± SD percentage of CD8+ T cells after 7 days post challenge (DPC) but, the mean ± SD percentage of CD4+ T-cell population slightly declined at 7 DPC and enhanced after 14 DPC. Significant differences (P < 0.05) of CD8+ and CD4+T cells population was also observed between vaccinated and unvaccinated sheep. The vaccine also significantly (P < 0.05) reduced BTV RNA load in PBMCs of vaccinated animals than unvaccinated animals following challenge. There were no significant difference (P > 0.05) in cytokine induction, BTV RNA load and CD8+ and CD4+cell count among BTV-1, 2, 10, 16 and 23 serotype challenges except significant increase in mean ± SD percentage of CD8+ in BTV-2 group. These findings put forwarded that binary ethylenimine inactivated montanide adjuvanted pentavalent bluetongue vaccine has stimulated cell mediated immune response and most importantly reduced the severity of BTV-1, 2, 10, 16 and 23 infections following challenge in respective group.

Highlights

Bluetongue (BT) is an arthropod-transmitted hemorrhagic disease of wild and domestic ruminants
Conditions. e sense and antisense gene-speci c primer pairs for speci c ampli cation of sheep cytokines IL-2, IL6, IL-12, IFN-α, IFN-γ, TNF-α and housekeeping gene βactin were designed by using Primer Quest Programme of Integrated DNA Technologies (IDT, Coralville, USA) utilizing NCBI GenBank sequence information
Results e pentavalent vaccine formulation of Bluetongue virus (BTV) serotypes 1, 2, 10, 16, and 23 was assured to be free from bacteria, viruses, fungi or mycoplasma contamination by sterility test. e e cacy, especially the T-Cell response to the inactivated pentavalent vaccine formulation prepared in the recommended adjuvant was estimated by in-vivo experiments

Summary

Introduction

Bluetongue (BT) is an arthropod-transmitted hemorrhagic disease of wild and domestic ruminants. E disease is caused by Bluetongue virus (BTV) which is prototype species of the genus Orbivirus in the family Reoviridae [3, 4]. There are 27 recognized serotypes (BTV-1 to -27) with additions of the 25th serotype (“Toggenburg orbivirus”) from Switzerland in goat and. India is endemic with BT with rst report in the year 1968 and 23 out of 27 serotypes are prevailing in the country [9]. Due to wide antigenic heterogeneity among the serotypes, single strain of BTV in the vaccine does not o er cross protection. Systematic vaccination is only e ective tool to prevent clinical disease and virus spread. Modi ed live virus (MLV) and inactivated vaccines have been used to limit the outbreaks of BTV in the world including in India

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