Role of rotavirus vaccination on G9P[8] rotavirus strain during a seasonal outbreak in Japan.

Although two live oral rotavirus (RV) vaccines, Rotarix and RotaTeq, play a critical role toward reducing disease severity, hospitalization, and death rate in RV infections, regular monitoring of vaccine effectiveness (VE) is yet necessary because the segmented genome structure and reassortment capability of RVs pose considerable threats toward waning VE. In this study, we examined the VE by a test-negative study design against G9P[8]I2 strain during a seasonal outbreak in February-May, 2018, in an outpatient clinic in Kyoto Prefecture, Japan. It remains important because G9P[8]I2 strain remains partially heterotypic to these vaccines and predominating in post-vaccination era.

Emergence of intragenotype recombinant sapovirus in Japan.

Sapovirus is an important causative agent of sporadic cases as well as of outbreaks of acute gastroenteritis in humans worldwide. A total of 603 fecal specimens collected from July 2005 to June 2006 from children with acute gastroenteritis in five localities in Japan (Maizuru, Tokyo, Sapporo, Saga, and Osaka) were screened for sapovirus by RT-PCR. It was found that 17 specimens were positive for sapovirus and it represented 2.

Detection and genetic characterization of group A rotavirus strains circulating among children with acute gastroenteritis in Japan.

A total of 603 fecal specimens collected from July 2005 to June 2006 from children with acute gastroenteritis, encompassing five different localities in Japan, were screened for group A rotavirus by reverse transcription-PCR. It was found that 117 fecal specimens (19.4%) were positive for group A rotavirus.

Genetic characterization of group A rotavirus strains circulating among children with acute gastroenteritis in Japan in 2004-2005.

A total of 752 fecal specimens collected from July 2004 to June 2005 from children with acute gastroenteritis in four localities in Japan (Maizuru, Tokyo, Sapporo, and Osaka) were screened for group A rotavirus by RT-PCR. It was found that 82 (10.9%) specimens were positive for group A rotavirus.

Novel intragenotype recombination in sapovirus.

Based on the genetic analysis, a novel, naturally occurring recombination between two distinct sapovirus subtypes (subtype a and subtype b) within genogroup I genotype 1 was identified. Breakpoint analysis of recombinant sapovirus showed that the recombination site was at the polymerase-capsid junction. This is the first report of the existence of acute gastroenteritis caused by intragenotype recombinant sapovirus.