VP7 Serotype Research Articles

Serological response to rotavirus infection in newborn infants

We report the identification of rotavirus in stools of newborn infants at the "Hospital Materno Infantil de Caricuao" (HMIC) as well as the infants' serological responses to various rotavirus strains. The serological responses of another group of rotavirus-positive neonates studied previously at the "Maternidad Concepcion Palacios" (MCP) hospital was also evaluated. Fifty-four of 266 (20%) newborns examined at HMIC shed rotavirus. The infection rate was higher among infants admitted to the nursery (75%) than in those "rooming in" with their mothers (7%) (P < .01). Eleven of the 54 neonates (20%) had diarrhea; seven of them experienced mild, short-lived episodes, whereas five had frequent diarrhea bouts or diarrhea lasting for over 3 days; the remaining 43 infants were asymptomatic. Twenty-seven of 28 rotavirus specimens tested at HMIC had VP7 serotype 4 specificity and one belonged to VP7 serotype 1; VP4 typing performed on 24 of the viruses by RNA hybridization showed these viruses to be similar to the M37 strain, a rotavirus previously associated with asymptomatic infections in newborns at MCP. IgA seroresponses were detected in eight of 11 infants born at HMIC (73%), but most failed to developed neutralization responses to homologous or heterologous strains. Newborn infants who had shed the M37 rotavirus strain at MCP reacted similarly: 16 of 24 (67%) developed a rotavirus IgA rise, but only 29% developed a neutralization response.

A new serotype of the outer capsid protein VP4 shared by an unusual human rotavirus strain Ro1845 and canine rotaviruses

The VP4 protein of human rotavirus (HRV) strain Ro1845 and canine rotavirus strains K9 and CU-1 exhibited greater than 98% amino acid identity within their group, but showed less identity with VP4 proteins of other HRV and animal rotavirus strains, the simian rotavirus strain RRV VP4 being most similar to them (90% amino acid identity). To exclude the possibility that these three strains were members of the RRV VP4 serotype P3, neutralization studies were performed using antisera to reassortant viruses containing the VP4 gene from each of Ro1845, CU-1 and RRV. The result established close antigenic similarity among the VP4 proteins of Ro1845, K9 and CU-1 and revealed only a marginal degree of similarity between the VP4 proteins of these three strains and that of strain RRV. These sequence and serological data suggest that the VP4 proteins of Ro1845, K9 and CU-1 represent a new P serotype which we propose to assign P13.

VP4 serotype of the Gottfried strain of porcine rotavirus

The antigenic relationships of the VP4 serotype of porcine rotavirus Gottfried strain with other rotaviruses were determined by using antiserum to Gottfried VP4-baculovirus recombinant. This antiserum failed to react significantly with virus of serotypes P1A, P1B, P3, and OSU; however, it reacted with P2 strains. In the reciprocal assay, antiserum to VP4 of an asymptomatic strain (P2) failed to neutralize the Gottfried strain virus to a significant level. It thus appears that the Gottfried strain should be considered a subtype of P2.

Electrophoretic typing of nosocomial rotavirus infection in a general paediatric unit showing the continual introduction of community strains

During 1989 stool specimens from hospitalised children with gastroenteritis at Ga-Rankuwa Hospital in South Africa were examined for the presence of rotaviruses. Overall 16% of the children were positive for rotavirus. However, 43% of the rotavirus positive patients were infected in the hospital. Further characterisation of the rotavirus strains was performed by electrophoresis of the RNA genome and hybridisation analysis of the VP7 and VP4 genes present. The strains associated with nosocomial infection were similar to those strains acquired in the community. The majority of the strains, both community- or hospital-acquired, were associated with a serotype 1 strain with a long electrophoretype and bearing the Wa-like VP4 gene. Three minor rotavirus strains with a long electrophoretype were also observed to be circulating bearing serotype 1 or 4 VP7 genes and the Wa-like VP4 gene. Interestingly, a serotype 4 strain bearing the M37-like VP4 gene was identified to occur almost exclusively in neonates although the gene was associated with diarrhoea in these cases. Two strains with differing short RNA electrophoretypes were also observed, members of which hybridised to VP7 serotype 2 and VP4 DS-1 type probes.

A comparative evaluation of the safety and immunogenicity of a single dose of unbuffered oral rhesus rotavirus serotype 3, rhesus/human reassortant serotypes 1, 2 and 4 and combined (tetravalent) vaccines in healthy infants

To assess safety and immunogenicity, 213 healthy infants aged 6 weeks to 4 months were randomized to receive a single dose of placebo, a 10 4 or 10 5 p.f.u. dose of rhesus rotavirus (RRV) serotype 3, human—RRV reassortant (VP-7 serotypes 1, 2 or 4) or a 10 4 or 10 5 p.f.u. dose of tetravalent rotavirus vaccine (containing equal parts of serotype 1, 2, 3 and 4 strains). The infants were fed ad libitum before and after vaccination; no buffer was used. For 7 days after vaccination, potential vaccine side effects were monitored, and no significant differences were noted for any symptom evaluated among the single serotype, tetravalent or placebo groups. Sera, obtained before and 28 days after vaccination, were measured for antibody to rotavirus by IgG, IgA and IgM enzyme-linked immunosorbent assay in all subjects, and by neutralizing antibody to the individual serotypes by plaque reduction in placebo and tetravalent vaccinees. The serological response rates for serotypes 1, 2, 3, 4 and the tetravalent vaccine were 25, 12, 19, 11 and 22%, respectively, at 10 4 p.f.u.; 47, 50, 35, 29 and 61%, respectively, at 10 5 p.f.u.; and 37% for placebo. The tetravalent vaccine was more immunogenic at 10 5 than at 10 4 p.f.u. ( p = 0.04). Grouped together, the vaccines at 10 5 p.f.u. (single serotype and tetravalent) were more immunogenic than the vaccines at 10 4 p.f.u. (38 of 85 versus 17 of 94 seroresponders; p < 0.001). However, there was no difference between the serological response rates in the vaccine and placebo recipients as a consequence of the high seroconversion rate in the placebo group, which we postulate was produced by asymptomatic wild-type rotavirus infection. We conclude that a single dose of unbuffered rhesus or rhesus—human reassortant vaccine (VP-7 serotypes 1, 2, 3 or 4), or as a tetravalent preparation at 10 4 and 10 5 p.f.u. is safe but not adequately immunogenic and that asymptomatic wild-type rotavirus infections can occur year-round in the United States, affecting rotavirus seroresponsivity and its interpretation.

Identification and baculovirus expression of the VP4 protein of the human group B rotavirus ADRV

A complete cDNA copy of the fourth RNA segment of the human group B rotavirus adult diarrheal rotavirus (ADRV) has been cloned into lambda phage and excised into plasmid pSK Bluescript. Gene segment 4 contains 2,303 bases and encodes one long open reading frame beginning at base 16 and terminating at base 2263. The encoded protein contains 749 amino acids, with a calculated molecular mass of 84.4 kDa and a pI of 6.1. Gene 4 cDNA was inserted into a recombinant baculovirus via homologous recombination. The gene 4 polypeptide migrates at 84 kDa when expressed either by a recombinant baculovirus or in vitro in a rabbit reticulocyte lysate. The gene 4 protein is immunoprecipitable by hyperimmune serum to ADRV, human ADRV convalescent-phase serum, a porcine group B rotavirus infection serum, and a monoclonal antibody made to ADRV virion. Guinea pig hyperimmune serum to the baculovirus-expressed ADRV VP4 protein recognizes virus and immunoprecipitates an 84-kDa protein from in vitro translations of total ADRV mRNA. In addition, the gene 4-encoded protein shares significant amino acid identity and similarity with the group A rotavirus VP4 protein. This information, together with our previous identification of an 84-kDa protein present on iodinated intact virion but not EDTA-treated ADRV, suggests that gene 4 encodes the VP4 protein equivalent present on the outer capsid of ADRV. The ADRV VP4 protein is also 58% identical to the IDIR rat group B rotavirus gene segment 3 protein. The substantial differences between these two group B VP4 proteins suggests that they are distantly related and likely to define two different group B rotavirus VP4 serotypes. The baculovirus-expressed VP4 protein should be useful for developing serotyping reagents and tests for human and animal group B rotaviruses as well as for addressing the role of VP4 in ADRV neutralization.

Human rotavirus K8 strain represents a new VP4 serotype.

The complete VP4 gene of the human rotavirus (HRV) K8 strain (G1 serotype) was cloned and inserted into the baculovirus transfer vector pVL941 under the control of the polyhedrin promoter. A K8VP4 recombinant baculovirus was obtained by cotransfection of Spodoptera frugiperda (Sf9) cells with transfer vector DNA containing the K8VP4 gene and wild-type baculovirus DNA. Infection of Sf9 cells with this VP4 recombinant baculovirus resulted in the production of a protein that is similar in size and antigenic activity to the authentic VP4 of the K8 strain. Guinea pigs immunized with the expressed VP4 developed antibodies that neutralized the infectivity of the K8 strain. This antiserum neutralized HRV strains belonging to VP4 serotypes 1A, 1B, and 2 with efficiency eightfold or lower than that of the homologous virus, indicating that the human rotavirus K8 strain represents a distinct VP4 serotype (P3). In addition, low levels of cross-immunoprecipitation of the K8VP4 and its VP5 and VP8 subunits with hyperimmune antisera to HRV strains representing different VP4 serotype specificities also suggested that the K8 strain possesses a unique VP4 with few epitopes in common with other P-serotype strains.

Distribution of conserved and specific epitopes on the VP8 subunit of rotavirus VP4

Three cDNA clones comprising the VP8 subunit of the VP4 of human rotavirus strain KU (VP7 serotype G1; VP4 serotype P1A) G1 were constructed. The corresponding encoded peptides were designated according to their locations in the VP8 subunit as A (amino acids 1 to 102), B (amino acids 84 to 180), and C (amino acids 150 to 246 plus amino acids 247 to 251 from VP5). In addition, cDNA clones encoding peptide B of the VP8 subunit of the VP4 gene from human rotavirus strains DS-1 (G2; P1B) and 1076 (G2; P2) were also constructed. These DNA fragments were inserted into plasmid pGEMEX-1 and expressed in Escherichia coli. Western immunoblot analysis using antisera to rotavirus strains KU (P1A), Wa (P1A), DS-1 (P1B), 1076 (P2), and M37 (P2) demonstrated that peptides A and C cross-reacted with heterotypic human rotavirus VP4 antisera, suggesting that these two peptides represent conserved epitopes in the VP8 subunit. In contrast, peptide B appears to be involved in the VP4 serotype and subtype specificities, because it reacted only with the corresponding serotype- and subtype-specific antiserum. Antiserum raised against peptide A, B, or C of strain KU contained a lower level of neutralizing activity than did that induced by the entire VP8 subunit. In addition, the serotype-specific neutralizing activity of anti-KU VP8 serum was ablated after adsorption with the KU VP8 protein but not with a mixture of peptides A, B, and C of strain KU, suggesting that most of the serotype-specific epitopes in the VP8 subunit are conformational and are dependent on the entire amino acid sequence of VP8.

Characterization of full-length and polymerase chain reaction-derived partial-length Gottfried and OSU gene 4 probes for serotypic differentiation of porcine rotaviruses.

To determine the VP4 (P type) specificity of porcine rotaviruses, full- and partial-length gene 4 probes were produced from cloned Gottfried and OSU porcine rotavirus genomic segment 4 cDNAs. The gene 4 segments from the prototype Gottfried (VP7 serotype 4) and OSU (VP7 serotype 5) porcine rotavirus strains were selected for study because of their distinct P types and the occurrence of rotaviruses with similar serotypes among swine. Partial-length gene 4 cDNAs were produced and amplified by the polymerase chain reaction (PCR) and encompassed portions of the variable region (nucleotides 211 to 612) of VP8 encoded by genomic segment 4. The hybridization stringency conditions necessary for optimal probe specificity and sensitivity were determined by dot or Northern (RNA) blot hybridizations against a diverse group of human and animal rotaviruses of heterologous group A serotypes and against representative group B and C porcine rotaviruses. The PCR-derived gene 4 probes were more specific than the full-length gene 4 probes but demonstrated equivalent sensitivity. The Gottfried PCR-derived probe hybridized with Gottfried, SB2, SB3, and SB5 G serotype 4 porcine rotaviruses. The OSU PCR-derived probe hybridized with OSU, EE, A580, and SB-1A porcine rotaviruses and equine H1 rotavirus. Results of the hybridization reactions of the PCR-derived gene 4 probes with selected porcine rotavirus strains agreed with previous serological or genetic analyses, indicating their suitability as diagnostic reagents.

Typing of human group A rotavirus with alkaline phosphatase-labeled oligonucleotide probes.

Rotavirus (RV) in stools of children less than 1 year of age with diarrhea in Bangkok in 1989 were serotyped by monoclonal enzyme immunoassay (MEIA). RNA extracted from these specimens was tested for hybridization with alkaline phosphatase (AP) and 32P-labeled oligonucleotides constructed from the nucleotide sequences of VP7 of human G types 1 (HuG1Ac), 2 (HuG2Ac), 3 (HuG3Ac), and 4 (HuG4Ac). Of 148 specimens that contained RV, 72% (106/148) hybridized with RV G type specific AP-labeled oligonucleotides compared to 47% (70/148) that were serotyped by MEIA (P less than 0.001). Of 68 specimens that contained only one VP7 serotype (G-type), as identified by MEIA, 94% (16/17) of G1, 90% (27/30) of G2, 57% (4/7) of G3, and 36% (5/14) of G4 RV hybridized with the AP-labeled HuG1Ac, HuG2Ac, HuG3Ac, and HuG4Ac oligonucleotides, respectively. The probes for G1, 2, 3, and 4 RV were specific for each G type. The results of hybridizing specimens with 32P- and AP-labeled oligonucleotides were similar. After transcription and amplification of cDNA of gene 9, AP-labeled RV G type specific oligonucleotides hybridized with 90% (134/148) of RV specimens. The high sensitivity of these nonimmunological techniques could be of value in identifying G types of RV during vaccine trials.

Severity of rotavirus infection in relation to serotype, monotype and electropherotype.

The aim of this study was to determine whether the severity of symptoms associated with rotavirus infection was related to the serotype of the infecting virus. Severity of clinical symptoms in 108 children admitted to hospital for treatment of rotavirus diarrhoea was retrospectively assessed using a scoring system for frequency and duration of vomiting and diarrhoea, degree of fever, acidosis and dehydration, and presence of electrolyte imbalance. Children were 6-30 months old and were fully weaned at onset of symptoms prior to admission to hospital. No other enteric pathogens were detected during the course of the illness. Serotypes and monotypes were identified using a panel of monoclonal antibodies. Gel electrophoresis of rotavirus RNA was performed to determine electropherotypes. Children surveyed were infected with serotype 1 (47), serotype 2 (15) or serotype 4 (46) rotaviruses. Comparisons of severity of clinical symptoms according to infecting serotype revealed no statistically significant differences between serotype 1, 2 or 4 infections. In addition, no differences were detected between different rotavirus strains within each serotype (as judged by electropherotype) including monotypes 1a or 1c. This study failed to reveal differences in virulence between rotavirus strains of different VP7 serotypes infecting young children.

Severity of rotavirus infection in relation to serotype, monotype and electropherotype

The aim of this study was to determine whether the severity of symptoms associated with rotavirus infection was related to the serotype of the infecting virus. Severity of clinical symptoms in 108 children admitted to hospital for treatment of rotavirus diarrhoea was retrospectively assessed using a scoring system for frequency and duration of vomiting and diarrhoea, degree of fever, acidosis and dehydration, and presence of electrolyte imbalance. Children were 6-30 months old and were fully weaned at onset of symptoms prior to admission to hospital. No other enteric pathogens were detected during the course of the illness. Serotypes and monotypes were identified using a panel of monoclonal antibodies. Gel electrophoresis of rotavirus RNA was performed to determine electropherotypes. Children surveyed were infected with serotype 1 (47), serotype 2 (15) or serotype 4 (46) rotaviruses. Comparisons of severity of clinical symptoms according to infecting serotype revealed no statistically significant differences between serotype 1, 2 or 4 infections. In addition, no differences were detected between different rotavirus strains within each serotype (as judged by electropherotype) including monotypes 1a or 1c. This study failed to reveal differences in virulence between rotavirus strains of different VP7 serotypes infecting young children.

Comparative amino acid sequence analysis of VP4 for VP7 serotype 6 bovine rotavirus strains NCDV, B641, and UK

In a previous study (S. Zheng, G. N. Woode, D. R. Melendy, and R. F. Ramig, J. Clin. Microbiol. 27:1939-1945, 1989), it was predicted that the VP7 serotype 6 bovine rotavirus strains NCDV and B641 do not share antigenically similar VP4s. In this study, gene 4 and the VP7 gene of B641 were sequenced, and the amino acid sequences were deduced and compared with those of NCDV and bovine rotavirus strain UK. Amino acid sequence homology in VP7 between the three strains was greater than 94%, confirming their relationship as VP7 serotype 6 viruses. VP4 of B641 showed amino acid homology to UK of 94% but only 73% homology to NCDV. Sequence comparison of a variable region of VP8 demonstrated amino acid homology of 53% between B641 and NCDV, whereas B641 and UK were 89% homologous in this region. These results confirm the earlier prediction that although the same serotype by VP7 reactivity, B641 and NCDV represent different VP4 serotypes. This difference in VP4 may have contributed to the lack of homotypic protection observed in calves, implicating VP4 as an important antigen in the active immune response to rotavirus infection in bovines.

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)

Experience with serotyping rotavirus strains by reverse transcription and two-step polymerase chain reaction with generic and type-specific primers

Six VP7 serotypes or G types (G1-G4, G8 and G9) occur in group A human rotaviruses. Gouvea et al. recently reported a novel G-typing method based on reverse transcription (RT)-polymerase chain reaction (PCR) amplification of the VP7 gene with type-specific primers [Gouvea, V. et al. (1990). Journal of Clinical Microbiology 28, 276-82]. When we followed their protocol, 40 (89%) of 45 faecal rotavirus specimens were typed into G1-G4 and G9. The five specimens that were untypeable by the RT-PCR method contained three G2 and two G4 rotavirus specimens which were identified by an ELISA using G type-specific monoclonal antibodies. On the other hand, the RT-PCR typing assay was able to determine the G type of the seven isolates that were untypeable by the ELISA. Of 33 faecal rotaviruses that were typed by both assays, 100% agreement of the result was observed. In addition, when applied to some animal rotaviruses, the RT-PCR method identified G3 feline and canine rotavirus strains. We conclude that further refinement of the RT-PCR assay is desirable in order to more readily type G2 and G4 strains, although this assay displayed an applicability to epidemiologic studies comparable with ELISAs.

Serotype-specific epitope(s) present on the VP8 subunit of rotavirus VP4 protein

cDNA clones representing the VP8 and VP5 subunits of VP4 of symptomatic human rotavirus strain KU (VP7 serotype 1 and VP4 serotype 1A) or DS-1 (VP7 serotype 2 and VP4 serotype 1B) or asymptomatic human rotavirus strain 1076 (VP7 serotype 2 and VP4 serotype 2) were constructed and inserted into the pGEMEX-1 plasmid and expressed in Escherichia coli. Immunization of guinea pigs with the VP8 or VP5 protein of each strain induced antibodies that neutralized the rotavirus from which the VP4 subunits were derived. In a previous study (M. Gorziglia, G. Larralde, A.Z. Kapikian, and R. M. Chanock, Proc. Natl. Acad. Sci. USA 87:7155-7159, 1990), three distinct serotypes and one subtype of VP4 outer capsid protein were identified among 17 human rotavirus strains that had previously been assigned to five distinct VP7 serotypes. The results obtained by cross-immunoprecipitation and by neutralization assay with antisera to the VP8- and VP5-expressed proteins suggest that the VP8 subunit of VP4 contains the major antigenic site(s) responsible for serotype-specific neutralization of rotavirus via VP4, whereas the VP5 subunit of VP4 is responsible for much of the cross-reactivity observed among strains that belong to different VP4 serotypes.

Temporal distribution of human rotavirus serotypes 1,2,3, and 4 in Venezuelan children with gastroenteritis during 1979-1989.

The temporal distribution and clinical severity of rotavirus VP7 serotypes 1, 2, 3, and 4 recovered from 427 Venezuelan children with acute gastroenteritis over a period of 11 years were studied. Rotavirus VP7 serotype was established by ELISA serotyping in 298 (69.78%) of the specimens while the serotype of the remaining 129 (30.21%) samples could not be determined. Of the specimens typed, 85 (19.90% of the total) were serotype 1, 43 (10.07%) were serotype 2, 105 (24.59%) were serotype 3, and 65 (15.22%) were serotype 4. Yearly changes in the frequency of individual serotypes were observed. The predominance of a single serotype with minor contribution from others was noted every year. In this study, serotype 1 appears to induce a less severe illness in comparison with serotypes 2, 3, and 4. No apparent association between the proportion of each serotype and the children's age were found.

Serologic and mucosal immune response to rotavirus infection in the rabbit model

We examined the humoral immune response to rotavirus infection in specific pathogen-free rabbits inoculated and challenged orally with rabbit Ala rotavirus (7.5 x 10(5) to 1 x 10(7) PFU). The humoral immune response in both serologic and mucosal samples was monitored by using total antibody enzyme-linked immunosorbent assays (ELISAs), isotype-specific ELISAs, and plaque reduction neutralization assays. Following a primary infection, all rabbits shed virus and serologic and mucosal antibody responses were initially detected by 1 week postinoculation. Intestinal immunoglobulin M was detected by 3 days postinoculation, and secretory immunoglobulin A was detected by 6 days postinoculation. Following challenge, rabbits were protected (no detectable virus shedding) from infection. An anamnestic immune response was observed only with mucosal neutralizing antibodies, and all serologic and mucosal immune responses persisted at high levels until at least 175 days postchallenge (204 days postinoculation). Detection of neutralization responses was influenced by the virus strain used in the neutralization assay; all inoculated rabbits developed detectable serum and intestinal neutralizing antibodies against the infecting (Ala) virus strain. Neutralization activity in both serum and mucosal samples was generally, but not exclusively, homotypic (VP7 serotype 3) after both primary and challenge inoculations with Ala virus. Heterotypic serum neutralization activity was observed with serotype 8 (9 of 12 rabbits) and 9 (12 of 12 rabbits) viruses and may be based on reactivity with the outer capsid protein VP4 or on a shared epitope in the C region of VP7. Comparisons of heterologous (serotype 3) and heterotypic neutralizing responses in mucosal and serologic samples revealed that 43% (21 of 49) of the responses were discordant. In 19 of 49 (39%) of these cases, a heterotypic serologic response was seen in the absence of a heterotypic mucosal response, but in 2 of 49 (4%) instances, a heterotypic mucosal response was seen in the absence of a concomitant serologic response. These results provide insight into factors which may affect detection of heterotypic responses.

VP4 monotype specificities among porcine rotavirus strains of the same VP4 serotype

The porcine rotavirus OSU strain was used to produce monoclonal antibodies (MAbs) directed against the outer capsid protein VP4. From two separate fusions, eight MAbs that inhibited hemagglutination activity of the OSU strain were selected. All MAbs immunoprecipitated both the OSU VP4 protein derived from a lysate of infected MA104 cells and the OSU VP4 protein expressed in Sf9 cells by a recombinant baculovirus. By immunoprecipitation of in vitro-translated OSU gene 4 transcripts of different length, the eight MAbs were found to be specific for the VP8 subunit of VP4. All MAbs neutralized the OSU strain but failed to neutralize human, bovine, and simian rotavirus strains. Antiserum to the expressed OSU VP4 protein was used to study the distribution of VP4 antigenicity among porcine rotaviruses. At least two distinct specificities were identified among 14 rotavirus strains that had been previously assigned to four distinct VP7 serotypes. Five groups of monotype specificities of the VP4 protein were identified by the eight anti-VP4 MAbs among 11 porcine strains that share the same VP4 serotype.

Nucleotide sequence of VP4 and VP7 genes of human rotaviruses with subgroup I specificity and long RNA pattern: implication for new G serotype specificity

We sequenced the genes coding for the two neutralization proteins, VP4 and VP7, of human rotavirus strains L26 and L27 with subgroup I specificity but the long RNA pattern. The deduced VP7 amino acid sequence of strains L26 and L27 showed a low homology (73.6 to 81.9%) to those of rotavirus strains of the established serotypes. This finding, together with the previous serological characterizations, suggests that the VP7 (G) serotype of the L26 and L27 strains is distinct from those of strains of the previously established serotypes. In contrast, the VP4 sequences of the L26 and L27 strains were quite similar to those of virulent serotype 2 strains (DS-1, S2, and RV-5).