Serological and genomic characterization of porcine rotaviruses in Thailand: detection of a G10 porcine rotavirus.

A total of 557 fecal specimens collected from piglets with diarrhea in Thailand were examined for rotavirus RNA by polyacrylamide gel electrophoresis. Twenty-three, one, and two samples were positive for group A, group B, and group C rotaviruses, respectively. Two samples exhibited two segments found in picobirnavirus RNA. RNA electropherotyping of 23 group A rotaviruses showed that they were classified into five patterns. By serotyping by enzyme-linked immunosorbent assay and PCR, viruses in 3 and 14 specimens were found to be serotype G3 and serotype G10, respectively. For one specimen, containing a serotype G10 virus (strain P343), virus was isolated in MA-104 cells, and the nucleotide sequences of the VP7 and VP4 genes were determined. Comparative sequence analysis and cross-neutralization tests showed that strain P343 has B223-like G10 and UK-like P7 serotype (or VP4 genotype 5) specificities. Rotaviruses having such antigenic specificities have not been detected in piglets. Thus, the interspecies transmission of rotaviruses between cows and pigs was suggested.

Survey on the distribution of the gene 4 alleles of human rotaviruses by polymerase chain reaction.

The presence of six gene 4 alleles (or VP4 genotypes) in human rotaviruses has been recognized. Using 16 representative cultivable human rotavirus strains, we confirmed the specificity of VP4 genotyping by polymerase chain reaction (PCR) using the nested oligonucleotides specific to each of the four representative gene 4 alleles. Using the PCR, we surveyed the gene 4 alleles of 199 human rotaviruses in stools collected in Japan and Thailand. Strains with the gene 4 allele, corresponding to P1A serotype, were shown to be the most prevalent, but two strains with P2 gene 4 allele and one strain with P3 gene 4 allele were detected in Thailand and in Japan, respectively.

Distinct yearly change of serotype distribution of human rotavirus in Thailand as determined by ELISA and PCR.

A total of 241 group A rotavirus-positive stool samples collected from diarrhoeic patients in Thailand between July 1988 and June 1991 were characterized for their serotypes by enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies and by a polymerase chain reaction (PCR). In July 1988-June 1989, serotype 1 was the most prevalent (63.4%), followed by serotype 4 (11.0%) and serotype 2 (8.5%). In July 1989-June 1990, 59.8% were serotype 1, 24.3% were serotype 2, and 6.1% were serotype 3. In contrast, in July 1990-June 1991, serotype 3 was detected in the highest frequency (40.5%), 29.9% were serotype 1, and 27.3% were serotype 2. Thus, a distinct yearly change of serotype distribution of rotavirus in Thailand was observed in the three consecutive years. In particular, it was of note that the prevalence of serotype 3 greatly increased, in contrast to the previous studies in which almost no serotype 3 rotaviruses were detected in the years 1983-8 in Thailand.

Identification of human and bovine rotavirus serotypes by polymerase chain reaction.

The use of the polymerase chain reaction (PCR) for identifying serotypes of human and bovine rotaviruses was examined. In the identification of 115 human rotavirus samples in stools, results with PCR showed excellent agreement with results of serotyping by an enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies. Furthermore, the PCR showed a much higher sensitivity (93%) than the ELISA test (82.6%). The PCR method could also be applied for identifying the serotype of bovine rotaviruses.

Antigenic and genetic analyses of human rotaviruses in Chiang Mai, Thailand: evidence for a close relationship between human and animal rotaviruses.

Serotyping of group A rotaviruses obtained from stools of 158 diarrheic patients in Chiang Mai, Thailand, by ELISA with monoclonal antibodies revealed a yearly change in the prevalence of individual serotypes. Three unusual human rotavirus strains were isolated. Strain Mc35 had subgroup I-serotype 10 antigen and a long RNA electrophoretic type, a property hitherto found only in bovine rotaviruses. RNA-RNA hybridization tests showed that the strain is more closely related genetically to bovine than to human rotaviruses. Strain Mc323, although serologically closely related to serotype 9, had subgroup I specificity and a long RNA electrophoretic type, a characteristic common to nonhuman rotaviruses. Strain Mc345, with an aberrant RNA pattern possibly due to genome rearrangement, had the same antigenic specificity as Mc323. These 2 strains were genetically very closely related to each other and were more related to porcine than to human rotaviruses. These results provide insights into the evolutionary mechanisms of human rotaviruses.

Analysis of human rotavirus strains prevailing in Bangladesh in relation to nationwide floods brought by the 1988 monsoon.

The virologic character of human rotavirus strains prevailing in Bangladesh was investigated in relation to the devastating nationwide floods brought by the 1988 monsoon. Human rotaviruses contained in stool specimens that were collected from inpatients with infantile and adult diarrhea in two hospitals in Mymensingh over a 13-month period (January 1988 to January 1989) and in one hospital in Dhaka over a 3-month period (February to April 1988) were examined for their subgroup, VP7 serotype, and RNA electropherotype. In concurrence with the spread of the flood (from the middle of August 1988), the number of infantile and adult diarrhea patients increased greatly. At the same time, the proportion of rotavirus-positive specimens in all diarrhea cases also increased remarkably, reaching 54 and 45% in September and October, respectively. An electrophoretic analysis of viral RNA revealed 17 distinct patterns of viral RNA (14 long and 3 short electropherotypes) and a considerable number of mixed electropherotypes, suggesting the simultaneous infection of some patients with more than two rotavirus strains. It was noteworthy that electropherotypes of rotavirus strains prevailing in the community changed considerably after the spreading of the flood and that the frequency of virus specimens showing mixed electropherotypes increased significantly during the flood period. These results suggest that sudden environmental change caused by the devastating floods seriously affected the epidemiology of rotavirus infections by increasing the opportunity of transmission of the virus and by reducing the resistance of the host to infection. In both pediatric and adult patient groups, serotypes 1 and 2 were the most frequent ones detected, followed by serotype 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigenic and genetic analyses of human rotavirus with dual subgroup specificity.

In our previous study (S. Urasawa, T. Urasawa, K. Taniguchi, F. Wakasugi, N. Kobayashi, S. Chiba, N. Sakurada, S. Morita, O. Morita, M. Tokieda, T. Kawamoto, K. Minekawa, and M. Oseto, J. Infect. Dis. 160:44-51, 1989) of antigenic characterization of about 300 human rotavirus (HRV) isolates collected at different localities in Japan, we found 4 HRV isolates having unique antigenic and genetic constructions. The four strains possessed both subgroup I and subgroup II antigens, serotype 3 antigen, and a long RNA electropherotype. The reactivity pattern of these four HRV isolates with three monoclonal antibodies (MAbs) directed to an outer capsid protein, VP4, and with one MAb directed to an inner capsid protein, VP2, was clearly different from those of usual subgroup II HRVs having serotype 1, serotype 3, or serotype 4 specificity and a long RNA pattern, whereas their reactivity pattern was similar to that of strain K8 (subgroup II, serotype 1), which possessed unique VP4 and VP2 proteins. RNA-RNA cross-hybridization analysis indicated that while the four isolates were genetically distinct from the two genetic groups of HRV reported previously, i.e., the Wa family (strains KU, S3, and YO) and the DS-1 family (strain S2), they were closely related to strain K8, a strain having unique antigenic and genetic properties (K. Taniguchi, K. Nishikawa, T. Urasawa, S. Urasawa, K. Midthun, A. Z. Kapikian, and M. Gorziglia, J. Virol. 63:4101-4106, 1989).

Presumptive seventh serotype of human rotavirus.

Four group A human rotaviruses having antigenic specificity of subgroup I and 'long' RNA electropherotype were isolated in MA104 cell cultures. Cross-neutralization tests with hyperimmune antisera suggested that they are serologically distinct from the six previously recognized human rotavirus serotypes.

Characterization by enzyme-linked immunosorbent assay using subgroup- and serotype-specific monoclonal antibodies of human rotavirus obtained from diarrheic patients in Bangladesh.

By enzyme-linked immunosorbent assay with group A-, subgroup-, and serotype-specific monoclonal antibodies (MAbs), we tested 414 stool specimens collected from pediatric and adult patients hospitalized with acute gastroenteritis between January and June 1988. Of 414 specimens tested, 124 (30%) were positive for group A rotavirus. The subgroup was determined in 110 specimens (88.7%); 16.1% were subgroup I, and 72.6% were subgroup II. Two specimens reacted with both subgroup I- and subgroup II-specific MAbs. Serotype determinations showed that serotype 1 (38.4%) was predominant over serotypes 2 (28.2%), 3 (2.5%), and 4 (23%). Three specimens reacted with more than one serotype-specific MAb. While the frequency of serotype 1 was highest in the two hospitals in Mymensingh, serotype 2 was most prevalent in one hospital in Dhaka. All human rotavirus strains with subgroup I and serotype 2 specificities showed a short electropherotype, and all but one strain with subgroup II and serotype 1, 3, or 4 specificities exhibited a long electropherotype.

Survey of human rotavirus serotypes in different locales in Japan by enzyme-linked immunosorbent assay with monoclonal antibodies.

To investigate the relative frequency of individual human rotavirus serotypes prevailing in Japan, 562 stool specimens collected from patients with rotavirus gastroenteritis between November 1986 and March 1988 in seven districts were examined by an enzyme-linked immunosorbent assay (ELISA) with serotype 1-, 2-, 3-, and 4-specific monoclonal antibodies. Serotype 1 was the predominant serotype in the winter of 1986-1987; however, both serotypes 1 and 2 were detected frequently in the winter of 1987-1988. The results showed the relative frequency of individual serotypes by locale and the yearly change in the prevalence of each serotype in the same area. The result of subgroup specificity of rotavirus obtained by using ELISA with subgroup I- and II-specific monoclonal antibodies confirmed the general finding that rotavirus strains having subgroup I specificity are serotype 2 and those having subgroup II specificity are either serotype 1, 3, or 4. Unusual strains having both subgroup I and II specificity or neither specificity and strains presumed to represent new serotypes were also found.