Diversity of Rotavirus VP7 and VP4 Genotypes Associated with Severe Childhood Diarrhea in North West Cameroon: Detection of Unusual Strains G1P[6], G2P[6], G2P[8] and G3P[6]

Aims: To determine rotavirus genotypes and distribution among children 0 - 5 years old with severe acute diarrhea in the North West Region (NWR) of Cameroon.
Study Design: Cross sectional.
Place and Duration of Study: Hospitals and health centers in the NWR served as sample collection centers between January and December 2004.
Methodology: Fifty-six Enzyme Immunoassay (EIA) and Polyacrylamide gel electrophoresis (PAGE) - positive rotavirus stool specimens were analyzed for VP7 and VP4 genotypes by reverse transcriptase polymerase chain reaction (RT-PCR).
Results: A total of 51 (91.1%) samples genotyped as G and P types while the remaining five samples (8.9%) were partially characterized. Four VP7 genotypes (G1, G2, G3 and G9) and two VP4 genotypes, P[6] and P[8] were detected. The predominant G and P types were; G3 (34%) and P[8] (41.1%). Genotypes G1-G3 accounted for 85.8% of isolates while G9 represented 3.6% of isolates. Genotype P[6] represented 30.4% of all VP4 genotypes and was the most widespread strain occurring in all age groups. Twelve single G and P-type combinations were identified. Genotype G1P[8] (19.6%) predominated, followed by G3P[6] (17.9%). Unusual strains detected were G1P[6], G2P[6], G2P[8] and G3P[6] accounting for 32% of cases. Mixed infections were detected from 15 (27%) isolates comprising G1/G3P[6], G2/G9P[6], G2P[6]/P[8] and G1/G3/G8 P[6]/P[8]. Twenty isolates (35.7%) had unusual genotype / electropherotypes combinations. All G9 strains, mixed G genotypes and strains with atypical electrpherotypes occurred in children hospitalized with severe gastroenteritis.
Conclusion: There is high incidence of unusual rotavirus strains circulating in the NWR of Cameroon that could have an impact on rotavirus vaccine performance. Future studies will investigate post vaccine prevalence and characterization of non-typeable strains by other methods.