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Detection and characterization of novel rotavirus strains in the United States
M Ramachandran1, J R Gentsch, U D Parashar
1Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Insights
This study monitored rotavirus strains in the U.S. before potential vaccination, finding common types and identifying emerging uncommon strains like G9. Further research is needed to determine their epidemiological significance.
Area of Science:
- Virology
- Public Health
- Epidemiology
Background:
- Rotavirus is a leading cause of severe diarrheal disease in children globally.
- Establishing a rotavirus strain surveillance system is crucial for monitoring vaccine impact and pathogen evolution.
- Understanding prevalent and emerging rotavirus strains informs public health strategies and vaccine development.
Purpose of the Study:
- To establish a rotavirus strain surveillance system in the United States.
- To monitor prevalent G serotypes before and after anticipated rotavirus vaccination.
- To identify the emergence of uncommon rotavirus strains.
Main Methods:
- Characterization of 348 rotavirus strains from children with diarrhea (1996-1997).
- Utilized monoclonal antibody immunoassay, reverse transcription-PCR, and hybridization for P and G typing, subgrouping, and electropherotyping.
- Sequence analysis of VP7 gene and G9-specific monoclonal antibody binding confirmed G9 serotype.
Main Results:
- The four most common worldwide strains (P[8]G1, P[4]G2, P[8]G3, P[8]G4) comprised 83% of isolates.
- Uncommon strains, including P[6]G9 (5.5%) and P[8]G9 (1.7%), constituted 9.2% of isolates.
- High detection rates of G9 (7.2%) and P[6] (6.9%) specificities in multiple U.S. cities suggest emergence or past diagnostic limitations.
Conclusions:
- The study identified common and emerging rotavirus strains in the U.S. prior to widespread vaccination.
- Evidence strongly suggests U.S. G9 strains belong to serotype G9.
- The emergence of unusual strains like G9 warrants further investigation into their epidemiological importance.
Abstract:
We recently established a rotavirus strain surveillance system in the United States to monitor the prevalent G serotypes before and after the anticipated implementation of a vaccination program against rotavirus and to identify the emergence of uncommon strains. In this study, we examined 348 rotavirus strains obtained in 1996 to 1997 from children with diarrhea in 10 U.S. cities. Strains were characterized for P and G types, subgroups, and electropherotypes by using a combination of monoclonal antibody immunoassay, reverse transcription-PCR, and hybridization. The four strains most commonly found worldwide comprised 83% of the isolates (P[8]G1, 66.4%; P[4]G2, 8.3%; P[8]G3, 6.9%; P[8]G4, 1.4%), but 9.2% were unusual strains (P[6]G9, 5.5%; P[8]G9, 1.7%; P[6]G1, 1.4%; and P[4]G1 and P[8]G2, 0. 3% each). Strains not typeable for P or G type accounted for 5.5% of the total, while 2.3% of the strains had more than one G type (mixed infections). All P[6]G9 strains tested had short electropherotypes and subgroup I specificity and were detected in 4 of 10 cities, while P[8]G9 strains had long electropherotypes and subgroup II VP6 antigens. Both sequence analysis of the VP7 open reading frame (about 94 to 95% amino acid identity with the VP7 gene of G9 prototype strain WI61) and binding to a G9-specific monoclonal antibody strongly suggest that U.S. G9 strains belong to serotype G9. The high detection rates of unusual rotaviruses with G9 (7.2%) or P[6] (6.9%) specificity in multiple U.S. cities suggest the emergence of new strains or inadequate diagnosis in the past. The epidemiologic importance of these strains remains to be determined.