Immunogenicity and Efficacy Evaluation of Vero Cell-Adapted Infectious Bursal Disease Virus LC-75 Vaccine Strain

Wakjira Kebede; Molalegne Bitew; Fufa Dawo Bari; Bedaso Mammo Edao; Hawa Mohammed; Martha Yami; Belayneh Getachew; Takele Abayneh; Esayas Gelaye

doi:10.2147/VMRR.S326479

Immunogenicity and Efficacy Evaluation of Vero Cell-Adapted Infectious Bursal Disease Virus LC-75 Vaccine Strain

Vet Med (Auckl). 2021 Oct 1:12:261-270. doi: 10.2147/VMRR.S326479. eCollection 2021.

Authors

Wakjira Kebede¹, Molalegne Bitew², Fufa Dawo Bari³, Bedaso Mammo Edao³, Hawa Mohammed¹, Martha Yami¹, Belayneh Getachew¹, Takele Abayneh¹, Esayas Gelaye¹

Affiliations

¹ National Veterinary Institute, Bishoftu, Ethiopia.
² Ethiopian Biotechnology Institute, Addis Ababa, Ethiopia.
³ College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, Ethiopia.

Abstract

Introduction: Infectious bursal disease virus (IBDV) is an avian viral pathogen that causes infectious bursal disease (IBD) of chickens. The disease has been endemic in Ethiopia since 2002, and vaccination has been practiced as the major means of disease prevention and control. An IBD vaccine is produced in Ethiopia using primary chicken embryo fibroblast (CEF) cell, which is time-consuming, laborious, and uneconomical. The present study was carried out to develop cell-based IBDV LC-75 vaccine using Vero cells and to evaluate the safety, immunogenicity and protection level.

Methods: Identity of the vaccine seed was confirmed with gene-specific primers using reverse transcription polymerase chain reaction (RT-PCR). Confluent monolayer of Vero cells was infected with vaccine virus and serial passage continued till passage 10. A characteristic virus-induced cytopathic effect (CPE) was observed starting from passage 2 on the third day post-infection. The infectious titer of adapted virus showed a linear increment along the passage level. The virus-induced specific antibody was determined using indirect ELISA after vaccination of chicks through ocular route.

Results: The antibody titer measured from Vero cells vaccinated chicks revealed similar level with the currently available CEF cell-based vaccine, hence no significant difference. Chicks vaccinated with Vero cell adapted virus showed complete protection against very virulent IBDV, while unvaccinated group had 60% morbidity and 25% mortality.

Conclusion: It is concluded that the IBDV vaccine strain well adapted on Vero cells and found to be immunogenic induces antibody development and successfully protects chicks against challenge with the circulating field IBDV isolate. Hence, it is recommended to produce IBD vaccine using Vero cell culture at the industrial scale to conquer the limitations caused by using CEF cells and thus to vaccinate chicks population to protect against the circulating IBDV infection.

Keywords: IBD vaccine; Vero cell; antibody; chicks; immunogenicity; protection.

Grants and funding

The research was funded by the National Veterinary Institute (NVI) by providing the laboratory facilities, reagents, consumables and animal experiment rooms. The Ministry of Innovation and Technology (MInT) of Ethiopia financially supported the research activities through the project “Development of a novel immuno prophylaxis for Infectious Bursal Disease and Fowl cholera from local isolates”. The funding bodies had no role in the design of the study, sample collection, statistical analysis and interpretation and writing of the manuscript.