Mutated G4P[8] Rotavirus Associated with a Nationwide Outbreak of Gastroenteritis in Nicaragua in 2005

Abstract

Rotavirus is the single most important etiologic agent of acute diarrhea mainly affecting children under the age of 5 (32). Each year human rotavirus (HRV) causes approximately 2 million hospitalizations and approximately 440,000 deaths, with the majority of the mortality in children from less industrialized countries (32).It is estimated that all children will be infected at least once by the age of 5 years (5), which leads to protective immunity later in life. In adults rotavirus infections are usually asymptomatic, but there are reports of disease in elderly and immunocompromised patients (1,4,26,28,33).Reports from different countries suggest an epidemiological shift of HRV strains over the years (20,30). It seems that one specific variant or lineage within the serotypes might be responsible for outbreaks in well-defined geographic regions; for instance, the lineage Ic of the strain G4P[8] increased in prevalence in some cities of Argentina in 1998 and 1 year later in Paraguay (7, 9). The lineage Ic of the G4P[8] strain was also found to circulate in Italy in 1999 and 2000 (3), and during the rotavirus season in 1997 the emergence of a G4P[6] strain with a different RNA profile was observed in South Africa (34). Furthermore, in Nicaragua the uncommon strain G4P[6] was observed to circulate at very low frequency in 2001 and 2002 (12). The emergence of these novel strains and new lineages is due to different evolutionary mechanisms including gene rearrangements, accumulation of point mutations, and reassortment of genome segments (18).During February and March 2005, one of the largest recorded outbreaks of severe acute gastroenteritis occurred in Nicaragua, affecting Ն64,000 individuals and causing at least 56 deaths, with children Ͻ5 years of age being most affected. We have carried out a molecular epidemiology study to investigate properties of the rotavirus strains associated with this unique and large epidemic outbreak. Our main observation was that the outbreak was associated with a mutated G4P [8] virus not previously detected in Nicaragua and most likely introduced from South America. The knowledge from this study may have implications for rotavirus prevention including vaccine introduction in Nicaragua. MATERIALS AND METHODSGeographic distribution of collected stool samples. During February and March 2005, a total of 108 stool samples were collected through a laboratorybased survey of acute diarrhea cases, defined as three or more liquid stools over a 24-h period (12-14). The surveillance was performed in the main hospital of every city included in this study; therefore, most of the samples (55/108; 76.4%) came from moderate to severe cases. A portion of the samples (17/72; 23.6%) was collected in the laboratory of the Department of Microbiology of the National Autonomous University of Nicaragua-Leon serving mainly outpatients.The stool specimens were stored at 4°C until transported to the Department of Microbiology of the National Autonomous University of Nicaragua-Leon. A suspension of 10% (vol/vol)...

Novel Light-Upon-Extension Real-Time PCR Assay for Simultaneous Detection, Quantification, and Genogrouping of Group A Rotavirus

“…The 22 specimens positive in the VP7-PCR were assigned to genogroup II, while 2 specimens were assigned to genogroup I, using the LUX real-time PCR assay. The genogroup I-positive specimens were determined to be G2P [4] (Table 3). From the 34 specimens collected at the Department of Clinical Microbiology, Linköping University Hospital, in total 15 were positive with all three methods ( Table 4).…”

“…The rest of the 19 specimens were negative by all three methods. The genogroup I-positive specimens were determined to be G2P [4] (Table 4). Furthermore, …”

“…Then, we compared the distribution of genogroups with the G and P types of the RV specimens and found that all RV genogroup I-positive specimens were associated with G2P [4] or G2 with unknown P type, with one genogroup I-positive specimen not possible to genotype. The independent genomic segregation of genogroup I and G2P [4] specificities has been shown before (17,20), which confirms the ability of the LUX assay to accurately determine genogroup specificity in unknown specimens.…”

“…Then, we compared the distribution of genogroups with the G and P types of the RV specimens and found that all RV genogroup I-positive specimens were associated with G2P [4] or G2 with unknown P type, with one genogroup I-positive specimen not possible to genotype. The independent genomic segregation of genogroup I and G2P [4] specificities has been shown before (17,20), which confirms the ability of the LUX assay to accurately determine genogroup specificity in unknown specimens. Identification of a specimen that contained a mix of genogroup I and II viruses identified as G2P [4] and G9P [8], which is in concordance with common RV genomic segregation patterns (17), demonstrates the ability of the assay to detect mixed infections of both genogroups.…”

“…RVs are furthermore classified into G and P types, based on gene analysis of the genes encoding the two outer capsid proteins (VP7 and VP4) (12,16). Although reassortment events often occur, there is evidence for independent segregation of RV genes; e.g., G1P [8] is associated with genogroup II, and G2P [4] is associated with genogroup I (17,20). The genogroups have also been associated with a difference in severity, with genogroup I infections causing less severe symptoms than genogroup II infections (32,36).…”