Characterization of Nontypeable Rotavirus Strains from the United States: Identification of a New Rotavirus Reassortant (P2A[6],G12) and Rare P3[9] Strains Related to Bovine Rotaviruses

Abstract

Among 1316 rotavirus specimens collected during strain surveillance in the United States from 1996 to 1999, most strains (95%) belonged to the common types (G1 to G4 and G9), while 5% were mixed infections of common serotypes, rare strains, or not completely typeable. In this report, 2 rare (P[9],G3) and 2 partially typeable (P[6],G?; P[9],G?) strains from that study were further characterized. The P[6] strain was virtually indistinguishable by hybridization analysis in 10 of its 11 gene segments with recently isolated P2A[6],G9 strains (e.g., U.S.1205) from the United States, but had a distinct VP7 gene homologous (94.7% a.a. and 90.2% nt) to the cognate gene from P1B[4],G12 reference strain L26. Thus, this serotype P2A[6],G12 strain represents a previously unrecognized reassortant. Three P3[9] strains were homologous (97.8-98.2% aa) in the VP8 region of VP4 to the P3[9],G3 feline-like reference strain AU-1, but had a high level of genome homology to Italian bovine-like, P3[9],G3 and P3[9],G6 rotavirus strains. Two of the U.S. P3[9] strains were confirmed to be type G3 (97.2-98.2% VP7 aa homology with reference G3 strain AU-1), while the other was most similar to Italian bovine-like strain PA151 (P3[9],G6), sharing 99.0% a.a. homology in VP7. Cross-neutralization studies confirmed all serotype assignments and represented the first detection of these rotavirus serotypes in the United States. The NSP4 genes of all U.S. P3[9] strains and rotavirus PA151 were most closely related to the bovine and equine branch within the DS-1 lineage, consistent with an animal origin. These results demonstrate that rare strains with P and G serotypes distinct from those of experimental rotavirus vaccines circulate in the United States, making it important to understand whether current vaccine candidates protect against these strains.

Modification of rotavirus multiplex RT‐PCR for the detection of G12 strains based on characterization of emerging G12 rotavirus strains from South India

“…G12 rotaviruses found in the far East and South America, were all associated with P[9], and were closely related to each other within lineage II [Pongsuwanna et al, 2002;Shinozaki et al, 2004;Castello et al, 2006]. The G12 strains reported from the US, UK, Bangladesh, and India from 2002 cluster within lineage III, and the lack of diversity within the gene encoding the VP7 suggests both a common ancestor and a recent introduction [Griffin et al, 2002;Das et al, 2003]. However, the association of G12 strains within lineage III with different P types, P[4], P[6], and P[8] suggests reassortment among commonly circulating strains.…”

A Study on the Origin of Bovine Rotavirus Strains Detected from the Children of the Nasu District, Tochigi, Japan

“…G6P [9] was originally isolated from an Italian child with diarrhea [5] and has subsequently been reported in the United States [6], Hungary [7], Japan [8], Australia [14,15], and Tunisia [16]. The authors [8] considered that their isolates represented reassortment events between bovine-like human rotaviruses and human/feline AU-1-like rotaviruses.…”

“…All specimens were stored at -80 °C until analyzed. G types [1][2][3][4]8,9,12], P types ( [4], [6], [8], [9]), VP6, and NSP4 genotypes were determined by the nested PCR with the primer sets reported previously [10][11][12].…”

“…While at least 11 G genotypes have been isolated from humans, G1, G2, G3, G4, and emerging G9 are major genotypes of human rotaviruses. As human P genotypes, P [8] is the most common genotype worldwide, followed by P [4] and P [6]. Also, 6 Non-Structural Proteins (NSP) are known.…”

“…In a study of Japanese cows, 59.1% of isolates belonged to G6. Usually, bovine G6 strains were combined with P [5], P [1], and P [11] worldwide [6,7].…”