Molecular and Serological Investigation of Infectious Bronchitis Virus in the East Shewa, Central Ethiopia

Abstract

Background

Infectious bronchitis (IB) is an economically important disease in poultry with worldwide distribution. The occurrence of IB has been reported both in commercial and backyard poultry in Ethiopia, although comprehensive information lacks available prevalence of the disease and the circulating serotypes.

Methods

A cross-sectional study was conducted from November 2021 to June 2022 in seven commercial farms found in East Shewa, Central Ethiopia. Serological assay using indirect ELISA, virus isolation techniques in embryonated eggs, and molecular techniques such as one-step reverse transcriptase polymerase chain reaction (RT-PCR) and nested polymerase chain reaction (PCR) targeting a 466 bp S1 gene were employed.

Results

A total of 196 blood samples, 7 pools (35) of swab samples, and 5 pools of tracheal samples were investigated. The results of serological analysis revealed that 97.96% (192/196; 95% CI: 94.86–99.44) of the sera samples were found to be positive for antibodies against IBV. Out of the 7 pools of swab and 5 pools of tracheal tissue samples analyzed using RT-PCR 33.3% (4/12) of them gave positive results all from swab samples. The RT-PCR-positive samples were subjected to a nested PCR yielding 295bp and 154bp indicating the circulation of Mass and 793/B (4/91) strains of IBV, respectively. The 12 pools of samples inoculated into embryonated egg showed cytopathic changes such as congestion, bleeding, and deformation only after three passages.

Conclusion

Two serotypes of IBV are circulating in Ethiopian chickens, and molecular identification of the Massachusetts serotype is the first report in Ethiopia. Further epidemiological investigation is needed in order to devise effective control measures.

Keywords:

• chickens
• Central Ethiopia
• IBV
• nested-PCR
• RT-PCR
• serology

Data Sharing Statement

All data generated or analyzed during this study are included in this published article.

Ethics Approval and Consent to Participate

This study design and method have been evaluated and endorsed by the Ethics Committee of Wollega University in compliance with relevant regulations, humane animal care standards, and the research protocol, as evidenced by the certification letter labeled with reference number WUSVMRE022/21. Consent Statement: Informed and written consent was obtained from all animal owners prior to involve in the study for the use of their cattle in this study.

Acknowledgments

We express our sincere gratitude to Addis Ababa University College of Veterinary Medicine and Wollega University School of Veterinary Medicine for their invaluable support, guidance, and assistance in the preparation of this manuscript. We also acknowledge the National Veterinary Institute for their provision of laboratory reagents, kits, and facilities support, without which this work would not have been possible. The authors extend special thanks to all the staff members who provided helpful suggestions and feedback on the manuscript.

Disclosure

The authors declare that they have no conflicts of interest to declare for this work.

Additional information

Funding

Authors declare there is no funding assigned/allocated for this Study.