Molecular epidemiology of genogroup II-genotype 4 noroviruses in the United States between 1994 and 2006.
Human noroviruses (NoVs) of genogroup II, genotype 4 (GII.4) are the most common strains detected in outbreaks of acute gastroenteritis worldwide. To gain insight into the epidemiology and genetic variation of GII.4 strains, we analyzed 773 NoV outbreaks reported to the CDC from 1994 to 2006. Of these NoV outbreaks, 629 (81.4%) were caused by GII viruses and 342 (44.2%) were caused by GII.4 strains. The proportion of GII.4 outbreaks increased from 5% in 1994 to 85% in 2006, but distinct annual differences were noted, including sharp increases in 1996, 2003, and 2006 each associated with newly emerging GII.4 strains. Sequence analysis of the full-length VP1 gene of GII.4 strains identified in this study and from GenBank segregated these viruses into at least 9 distinct subclusters which had 1.3 to 3.2% amino acid variation between strains in different subclusters. We propose that GII.4 subclusters be defined as having >5% sequence variation between strains. Our data confirm other studies on the rapid emergence and displacement of highly virulent GII.4 strains.
Gastroenteritis and Respiratory Viruses Laboratory Branch, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Du-Ping
DP
Zheng
Marc-Alain
MA
Widdowson
Roger I
RI
Glass
Jan
J
Vinjé
D017250:Caliciviridae Infections / Q000453:epidemiology* / Q000821:virology*; D036022:Capsid Proteins / Q000235:genetics; D016000:Cluster Analysis; D004196:Disease Outbreaks; D005759:Gastroenteritis / Q000453:epidemiology* / Q000821:virology*; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D029322:Norovirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014481:United States / Q000453:epidemiology
D036022:Capsid Proteins