Heterogeneity and Temporal Dynamics of Evolution of G1 Human Rotaviruses in a Settled Population

Abstract

A rotavirus sample collection from 19 consecutive years was used to investigate the heterogeneity and the dynamics of evolution of G1 rotavirus strains in a geographically defined population. Phylogenetic analysis of the VP7 gene sequences of G1P[8] human rotavirus strains showed the circulation of a heterogeneous population comprising three lineages and seven sublineages. Increases in the circulation of G1 rotaviruses were apparently associated with the introduction of novel G1 strains that exhibited multiple amino acid changes in antigenic regions involved in rotavirus neutralization compared to the strains circulating in the previous years. The emergence and/or introduction of G1 antigenic variants might be responsible for the continuous circulation of G1 rotaviruses in the local population, with the various lineages and sublineages appearing, disappearing, or cocirculating in an alternate fashion under the influence of immune-pressure mechanisms. Sequence analysis of VP4-encoding genes of the G1 strains revealed that the older strains were associated with a unique VP4 lineage, while a novel VP4 lineage emerged after 1995. The introduction of human rotavirus vaccines might alter the forces and balances that drive rotavirus evolution and determine the spread of novel strains that are antigenically different from those included in the vaccine formulations. The continuous emergence of VP7-VP4 gene combinations in human rotavirus strains should be taken into consideration when devising vaccination strategies.

Rotavirus genotypes in children in the Basque Country (northern Spain) over a 13-year period (July 1996–June 2009)

“…In line with the results of previous studies performed in developed countries in recent years, we observed predominant circulation of G1[P8] strains, the emergence of G9[P8] strains, and scarce detection of Gtype strains other than G1-G4 and G9 [2,9,[13][14][15]. In 14 of the 20 seasons after 1989, the main G-type was G1, a percentage similar to that also observed over a 20-year period (1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) in Palermo, Italy [16]. G1 caused more than half of the infections genotyped and showed significant circulation in all epidemics.…”

“…In contrast, circulation of the remaining genotypes, especially G2, G3 and G4, was intermittent and was undetectable for varying periods (1-3 years). The predominance of G1 strains could be due to the wide genetic and antigenic heterogeneity of the population of strains of this genotype [16].…”

Epidemiology and clinical features of gastroenteritis in hospitalised children: prospective survey during a 2-year period in a Parisian hospital, France

“…The second most frequent norovirus genotype found in this study was GGII.b. Several studies have reported this genotype as a cause of sporadic and outbreak cases of gastroenteritits in children, and some of these studies suggested that GGIIb was closely associated with infections in children [36][37][38][39][40]. In this study, the highest rates of GGIIb detection were observed in January-February 2002 and the fall and winter of [2003][2004].…”

Modeling rotavirus strain dynamics in developed countries to understand the potential impact of vaccination on genotype distributions

“…Evidence argues against such changes occurring. For example, it has been noted that closely related strains can persist over multiple seasons, and that greater genetic diversity can exist among strains belonging to a single G-type circulating in the same year than strains belonging to that same G-type reemerging 12-15 y later (43,54). It seems unlikely that such strains lose then regain some "fitness factor" during the intervening years.…”

“…To better understand the prevaccination cycling of rotavirus genotypes and calibrate our strain-specific model, we analyzed published time series of annual genotype distributions from six developed countries (43)(44)(45)(46)(47)(48)(49). Fourier analysis suggests that the predominant rotavirus strains cycle with periods (T) ranging from 3 to 11 y (Fig.…”