Evolutionary changes between pre- and post-vaccine South African group A G2P[4] rotavirus strains, 2003-2017.

The transient upsurge of G2P[4] group A rotavirus (RVA) after Rotarix vaccine introduction in several countries has been a matter of concern. To gain insight into the diversity and evolution of G2P[4] strains in South Africa pre- and post-RVA vaccination introduction, whole-genome sequencing was performed for RVA positive faecal specimens collected between 2003 and 2017 and samples previously sequenced were obtained from GenBank (n=103; 56 pre- and 47 post-vaccine). Pre-vaccine G2 sequences predominantly clustered within sub-lineage IVa-1. In contrast, post-vaccine G2 sequences clustered mainly within sub-lineage IVa-3, whereby a radical amino acid (AA) substitution, S15F, was observed between the two sub-lineages. Pre-vaccine P[4] sequences predominantly segregated within sub-lineage IVa while post-vaccine sequences clustered mostly within sub-lineage IVb, with a radical AA substitution R162G. Both S15F and R162G occurred outside recognised antigenic sites. The AA residue at position 15 is found within the signal sequence domain of Viral Protein 7 (VP7) involved in translocation of VP7 into endoplasmic reticulum during infection process. The 162 AA residue lies within the hemagglutination domain of Viral Protein 4 (VP4) engaged in interaction with sialic acid-containing structure during attachment to the target cell. Free energy change analysis on VP7 indicated accumulation of stable point mutations in both antigenic and non-antigenic regions. The segregation of South African G2P[4] strains into pre- and post-vaccination sub-lineages is likely due to erstwhile hypothesized stepwise lineage/sub-lineage evolution of G2P[4] strains rather than RVA vaccine introduction. Our findings reinforce the need for continuous whole-genome RVA surveillance and investigation of contribution of AA substitutions in understanding the dynamic G2P[4] epidemiology.

Novel human rotavirus genotype G5P[7] from child with diarrhea, Cameroon.

We report characterization of a genotype G5P[7] human rotavirus (HRV) from a child in Cameroon who had diarrhea. Sequencing of all 11 gene segments showed similarities to > or =5 genes each from porcine and human rotaviruses. This G5P[7] strain exemplifies the importance of heterologous animal rotaviruses in generating HRV genetic diversity through reassortment.

Isolation and identification of adenovirus recovered from the stool of children with diarrhoea in Lagos, Nigeria.

In order to establish the role of adenovirus in gastroenteritis in Nigerian children, stool samples were collected from 138 young children with gastroenteritis and 29 other age-matched controls. The samples were inoculated into 6 different tissue culture cell lines and isolates with characteristic CPE were subjected to CFT confirmation of the presence of adenovirus antigen. All the samples were screened for adenovirus by a commercially available enzyme immunoassay (Biotrin Adenovirus Antigen EIA) for the presence of the group antigen. Of the 138 stool samples from children with diarrhoea screened by EIA, only 23 (16.7%) were positive, while 4 (13.8%) of the 29 controls were also found positive. A greater proportion of the adenovirus-positive cases were aged between 13 and 24 months. There was no difference in the prevalence of the infection between male and female. The fastidious, enteric adenoviruses of subgroup F were sought utilizing a second EIA (AdenoClone), and occurred in 3.6% of the samples from diarrhoeic children and was not detected in the control group. There was no significant difference between the clinical symptoms of children infected with adenovirus and those not infected with adenovirus. However, the source of drinking water had a significant effect on the frequency of stool per day. The infection occurred all year round except for April and there was no significant correlation with the climatic factors. This study implies that the fastidious adenovirus is important in the aetiology of diarrhoeal illness in Nigerian children.