Browsing by Author "Mwape, Innocent"
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- ItemCharacterisation of rotavirus strains responsible for breakthrough diarrhoeal disease among Zambian children using whole genome sequencing(Stellenbosch : Stellenbosch University, 2024-01) Mwape, Innocent; De Beer, Corena; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology. Medical Virology.ENGLISH ABSTRACT: Background Genetically altered viruses or variants have the potential to increase their virulence, pathogenicity, transmission, and ability to evade both natural and vaccine-induced immune responses leading to diarrhoeal disease in under five-year-old children who have received all recommended doses of Rotavirus (RV) vaccines, also known as breakthrough infections. Studies characterising RV strains responsible for breakthrough infections are rare in resource-limited countries like Zambia where RV-associated diarrhoeal disease is endemic. We aimed to characterise RV strains detected in fully vaccinated under five-year-old children residing in Zambia using next generation sequencing. Methods This was a case study nested under an open label randomised controlled RV vaccine clinical trial that evaluated safety and immune boosting effects of a third dose of Rotarix compared to a two-dose schedule. The Rotaclone kit was used to screen for RV in stool. We performed VP7 and VP4 genotyping on RV positive stool using Sanger sequencing. Whole genome sequencing was done on the Illumina Miseq platform. Genome assembly was done using Geneious software and multiple sequence alignment using Muscle in MEGA version 6. Results A total of 76 diarrhoeal stool specimens were collected and screened for RV of which 4/76 (5.2%) were positive. Genotypes of three of the four cases were identified as G1P[4], G12P[4] and G12P[8] using Sanger sequencing. Whole genome analysis revealed that the RVA/Human-wt/ZMB/CIDRZRV2088/2020/G1P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 and RVA/Human-wt/ZMB/CIDRZ-RV2106/ 2020/G12P[4]-I1-R2-C2-M2-A2-N1-T2-E1-H2 strains were mostly DS-1-like with mono and multiple reassortant respectively, whilst the RVA/Human-wt/ZMB/CIDRZ-RV2150/2020/G12P[8]-I1-R1-C1- M1-A1-N1-T1-E1-H1 was a typical Wa-like strain. Comparison of VP7 antigenic epitope of strains causing breakthrough infections and Rotarix vaccine strains revealed several amino acid differences like G96P and M217E. Comparison of P[4] strains with VP4 of the Rotarix vaccine strain demonstrated two amino acids differences (P114Q and V115T) were P114Q is an immune escape mutation. Discussion and Conclusion Differences observed in amino acids in antigenic epitope suggested its role in the immune evasion of neutralising antibodies elicited by the vaccine. Findings from this study have potential to inform national RV vaccination strategies and the design of highly efficacious universal RV vaccines. Furthermore, there might be need to monitor strains that have escaped vaccine-induced immunity to prevent diarrheal diseases in children under five years of age.