Introduction:Rotavirus remains a major cause of severe gastroenteritis among children under five years of age worldwide, including in Ethiopia. Despite the introduction of vaccines, the virus continues to evolve through frequent mutation and genetic reassortment, resulting in substantial genetic diversity and raising concerns about potential vaccine escape. This study aimed to assess the prevalence, genotype distribution, and genetic characteristics of rotavirus A (RVA) strains circulating among children with diarrhea in central Ethiopia, and to compare these strains with the Rotarix® vaccine strain.
Methods: A cross-sectional study was conducted between April 2022 and December 2023 in health centers located in Debre Birhan and Addis Ababa. Stool samples were collected from children under five years presenting with diarrhea. RVA detection was performed using quantitative real-time PCR (qPCR), and genotyping was carried out through Sanger sequencing of the VP7 and VP4 genes. Amino acid sequences were analyzed to identify substitutions within key antigenic epitopes in comparison with the Rotarix® vaccine strain.
Results: RVA was detected in 30 out of 247 samples (12.14%), with 28 successfully genotyped. G9 was the predominant G genotype (50%), followed by G12, G2, G1, and G3, while a proportion remained untyped. Among P genotypes, P[4] was most common, followed by P[6] and P[8]. The dominant G/P combination was G9P[4]. Notably, multiple amino acid substitutions were observed in both VP7 and VP4 antigenic regions compared to the Rotarix® strain. Conclusion: These findings suggest ongoing viral evolution and highlight the need for continuous surveillance and evaluation of vaccine effectiveness.

Co-authors: Haileeyesus Adamu, Julia Bergholm, Johanna Lindahl, Anne-Lie Blomstrom, Mikael Berg, Tesfaye Sisay Tessema