Update of Rotavirus Strains Circulating in Africa From 2007 Through 2011

Abstract

There is high genetic diversity of rotavirus strains circulating in the subcontinent. Understanding the strain diversity pre- and postvaccine introduction are important in Africa to understand the broader impact of the rotavirus vaccines on regionally circulating strains.

Safety and immunogenicity of a parenterally administered rotavirus VP8 subunit vaccine in healthy adults

“…The less robust responses to the P [4] strains and meager responses to the P [6] strains raise the question of whether a multivalent vaccine, including subunits from these other strains would be necessary for a vaccine to be efficacious in diverse geographic areas. Although P [8] strains constitute the majority of strains identified globally, strains expressing P [4] constitute an appreciable proportion of strains identified in both Africa and Asia (up to 20%), while P [6] strains represent as much as 30% of clinical isolates in Africa [30][31][32].…”

Whole-genome analyses of DS-1-like human G2P[4] and G8P[4] rotavirus strains from Eastern, Western and Southern Africa

“…G8P[4] strains are considered medically important in Kenya in association with diarrhoeal diseases and have previously been detected in Kenya using RT-PCR assays that target the genes encoding the two RVA outer capsid proteins, VP7 and VP4 [15, 29]. In contrast, to the best of our knowledge, no G8P[4] complete genomes have been previously reported from Zimbabwe, Uganda, Zambia or Tanzania, even though the RVA G and P types from these countries are reported annually as part of the ongoing African rotavirus surveillance network [30, 31]. …”

Multiplexed one-step RT-PCR VP7 and VP4 genotyping assays for rotaviruses using updated primers

“…In 1992, the complimentary P genotyping multiplexed hemi-nested RT-PCR based assay was developed by Gentsch et al (1992), and in 2009 Simmonds et al established an alternative set of VP4 consensus primers (VP4F/VP4R) (Simmonds et al, 2008) for typing the P genotypes missed with the previously described Con3/Con2 consensus primers (Gentsch et al, 1992). These genotyping assays, some of which are more than 20 years old, have generated enormous amounts of useful epidemiological data which has highlighted RVA genetic diversity on a global level (Bányai et al, 2012; Gentsch et al, 2005; Matthijnssens et al, 2009; Seheri et al, 2014). Consequently, expanding genetic diversity, and genetic drift with the accumulation of point mutations at primer binding sites, have all been observed and linked to mistyping or failure of genotype-specific primers to correctly identify strains (Banyai et al, 2005; Cunliffe et al, 2001; Esona et al, 2010b; Mitui et al, 2012; Rahman et al, 2005; Solberg et al, 2009).…”

“…Ongoing failures of these decade-old assays to correctly characterize RVA strains have contributed to an estimated 10–30% of strains being classified as non-typeable, a definite hindrance to RVA research, worldwide (Esona et al, 2010a; Gentsch et al, 2005). With rapid changes in the epidemiology of RVA, and the emergence of genotypes G9 and G12 in many parts of the world (Banyai et al, 2012; Esona et al, 2013; Iturriza-Gomara et al, 2011; Seheri et al, 2014), it is imperative to be able to efficiently determine the VP7 and VP4 genotypes of RVA strains in clinical samples collected in the pre- and post-vaccine introduction eras. Vaccine effectiveness must be accessed against common VP7 and VP4 genotypes components of the vaccines, as well as those not included, and this is dependent on the accuracy and sensitivity of typing methods for RVA strains.…”

“…These genotyping assays have been invaluable in defining the importance of individual RVA G and P-types. They have been used to genotype approximately 110,000 strains, and also have highlighted RVA genetic diversity (Bányai et al, 2012; Gentsch et al, 2005; Matthijnssens et al, 2009; Seheri et al, 2014). On a global level, however, recent issues with the effectiveness of these typing assays have been identified.…”