Protection against severe rotavirus diarrhoea by rhesus rotavirus vaccine in Venezuelan infants

Rotavirus disease in Finnish children: use of numerical scores for clinical severity of diarrhoeal episodes

65 episodes of rotavirus diarrhoea, detected during a longitudinal follow-up of 336 infants from birth to 24-32 months of age, were analyzed for clinical symptoms. Rotavirus gastroenteritis was characterized by watery diarrhoea, vomiting (particularly in older children), fever and dehydration. A 0-20 point numerical score was devised according to the distribution of clinical features in the patients. Using this system, the mean severity score for the 65 episodes of rotavirus diarrhoea was 11.0 +/- 3.7 as compared to 5.6 +/- 3.2 for the 183 episodes of non-rotavirus diarrhoea in the same population (p less than 0.0001, t-test). The 20 point score is proposed for analysis of efficacy studies of candidate rotavirus vaccines.

Synthesis in Escherichia coli of the major glycoprotein of human rotavirus: analysis of the antigenic regions

Various regions of the gene encoding the major neutralization antigen, VP7, of human rotavirus have been expressed in Escherichia coli, as N-terminal fusions to beta-galactosidase under the control of the lac promoter. We have determined that the fusion products of two clones containing regions AB (aa 69-158) and ABC (aa 69-319) were antigenic, reacting with antibodies raised against whole virus. When guinea pigs were immunized with fusion protein purified by monoclonal antibody affinity columns, no neutralizing or virus-binding antibodies were detected, but antibodies binding to denatured VP7 were present.

Comparison of immunoglobulin A (IgA), IgG, and IgM enzyme-linked immunosorbent assays, plaque reduction neutralization assay, and complement fixation in detecting seroresponses to rotavirus vaccine candidates

In a phase 1 study to evaluate human-rhesus rotavirus reassortant vaccines, 116 infants 1 to 5 months of age received one of the following five preparations: the serotype 1 reassortant, the serotype 2 reassortant, rhesus rotavirus (serotype 3), a bivalent preparation (serotypes 1 and 3), or a placebo. Seroresponses to the different vaccines were measured by plaque reduction neutralization assay (PRNA); rotavirus-specific immunoglobulin A (IgA), IgG, and IgM enzyme-linked immunosorbent assays (ELISAs); and complement fixation (CF). The seroresponse rate, calculated by using a fourfold or greater antibody rise by any assay, was similar in the four vaccine groups (83 to 96%). When the data from all the vaccinees were pooled, IgA ELISA, IgG ELISA, and PRNA were comparable in detecting seroresponses (67, 62, and 70%, respectively) and more efficient than IgM ELISA (53%) and CF (44%). When the vaccinees were analyzed by age, the overall seroresponse rates were the same for infants 1 to 2 and 3 to 5 months old (90%). The IgA ELISA and PRNA were the most efficient for detecting antibody rises in both age groups. IgG ELISA was among the least efficient methods for detecting antibody rises in the younger age group but among the most efficient in the older age group (44 versus 78%). CF was among the least efficient methods in both age groups but was significantly better in the older age group than in the younger age group (54 versus 21%). Our findings show that ELISA, in particular rotavirus-specific IgA ELISA, is a sensitive indicator of vaccine takes in 1- to 5 month-old infants, the target population for vaccination. ELISA should also be very useful in demonstrating natural rotavirus infections in field studies in which a stool specimen from a diarrheal episode is not always available. The ELISA has the advantages of being easier and quicker and requiring less serum than PRNA, but it does not give serotype-specific information about the immune response.

Rotavirus serotypes causing acute diarrhoea in hospitalized children in Yogyakarta, Indonesia during 1978-1979

Rotavirus strains in stool specimens from 111 children aged 3-24 months admitted to hospital in Yogyakarta, Indonesia for treatment of acute diarrhoea were serotyped using VP7 serotype specific monoclonal antibodies in a double sandwich enzyme immunoassay. A serotype could be assigned to 59 of 111 specimens (53%). Inability to assign a serotype to 47% of specimens was probably due to loss of the outer capsid during transport of specimens from Indonesia to Australia. All four major human rotavirus serotypes were detected during the 15 month survey from June 1978 to August 1979, including one serotype 1, 5 serotype 2, 31 serotype 3, and 21 serotype 4 strains. One additional strain reacted with serotype 3 and 4 Mabs. Serotype 3 strains showed intratypic variation. The relative frequency of serotypes 2, 3, and 4 varied during the 15 months and appeared to be influenced by climatic changes associated with dry and wet seasons. Vaccine strategies must take account of comparatively rapid changes of predominant serotypes in a community and are only likely to be successful if comprehensive immunity can be established simultaneously against the four major human serotypes.

A trial of RIT-4237 rotavirus vaccine in 1-month-old infants

In a double blind placebo-controlled study rotavirus vaccine RIT 4237 was offered to young infants after the fourth week of life. The vaccine was very well tolerated. Fifty-seven out of 100 vaccine recipients and 10 out of 103 placebo recipients developed rotavirus-IgM-antibodies during the 1 month follow-up period. During a 6 month follow-up, stool samples from 2 out of 12 vaccinees and from 5 out of 12 placebo recipients contained rotavirus.

Reactogenicity and immunogenicity of rotavirus WC3 vaccine in 5-12 month old infants

Rotavirus is a major cause of acute gastroenteritis in infants worldwide and there is need for an effective vaccine. Rotavirus Wistar calf 3 (WC3) is a strain of bovine origin attenuated by 12 passages in cell culture. A lyophilized candidate vaccine containing 1 x 10(7) PFU of WC3 has been developed. An oral dose was given to 25 French infants 5-12-months old (mean age 8.6 months). No diarrhoea was observed within 2 weeks after vaccination. Unexplained vomiting was reported once and isolated fever greater than 37.8 degrees C was reported 3 times during the first week. One month later, a neutralizing antibody response to serotypes tested was shown in 88% of cases, with heterotypic responses to human serotype 3 (SA11 strain) in 72% and to type 1 (WA strain) in 48%. The percentage of immune response was similar whether the infant had antibody prior to immunization or not, but a booster effect was observed in children who had pre-immunization rotavirus antibodies. Considering these promising results, efficacy trials are in the planning in different parts of the world.

Determination of rotavirus serotype-specific antibodies in sera by competitive enhanced enzyme immunoassay

A method is described for the specific detection of antibody to individual rotavirus serotypes in sera. A competitive enzyme immunoassay (EIA) was developed in which rotavirus serotype-specific monoclonal antibodies against VP7 compete with antibodies in test sera for rotavirus serotype-specific antigen bound to a solid phase. There was an excellent correlation between serotype-specific EIA results and serotype-specific neutralization titres (r = 0.915, P = less than 0.001). The value of this method for rotavirus epidemiology and vaccine trials is discussed.

Reactions to and antigenicity of two human-rhesus rotavirus reassortant vaccine candidates of serotypes 1 and 2 in Venezuelan infants

The reactions to and antigenicity of two human-rhesus rotavirus (RRV) reassortants (human rotavirus strain D x RRV and human rotavirus strain DS1 x RRV) with the VP7 neutralization specificity of a serotype 1 or serotype 2 rotavirus were evaluated in a placebo-controlled double-blind trial in 116 1- to 5-month-old infants in Caracas, Venezuela. The children were randomly divided into five groups to receive orally the following inocula: (i) 10(4) PFU of D x RRV reassortant; (ii) 10(4) PFU of DS1 x RRV reassortant; (iii) 10(4) PFU of RRV; (iv) 5 x 10(3) PFU of D x RRV and 5 x 10(3) PFU of RRV; and (v) placebo. The children were examined daily for 7 days following vaccine administration; 8 to 26% of the vaccinated infants developed a mild febrile reaction which in most cases lasted only 1 day. Seroresponses to rotavirus were observed in 39 to 65% of the vaccinees by plaque neutralization assay and in 57 to 88% by an immunoglobulin A enzyme-linked immunosorbent assay. Vaccine shedding was detected in 53 to 86% of the vaccinees. Analysis of neutralization antibody responses indicates that the VP4 protein represents an important component of the response induced by the vaccines.

Dot hybridization assay for distinction of rotavirus serotypes

We have developed a hybridization assay that permits distinction of rotavirus serotypes 1, 2, 3, and 4. The serotype of rotaviruses from stool samples or tissue culture was recognized by hybridization of specific probes to (i) blots of viral double-stranded RNAs electrophoresed in agarose gels (Northern blots) or (ii) heat-denatured double-stranded RNAs directly dotted on nylon membranes. The probes consisted of 32P-labeled cDNA synthesized by reverse transcription of in vitro derived rotavirus mRNA from rotavirus serotypes 1 to 4. To prepare these probes, mRNAs were primed with a 17-mer nucleotide common to all four serotypes whose sequence is complementary to bases 375 to 391 of the rotavirus gene encoding the VP7 glycoprotein (gene 8 or 9 depending on the rotavirus strain). The resulting downstream transcripts encompassed areas of major sequence divergence among the four serotypes. Hybridization at high stringency (50 degrees C, 50% formamide, 4 x SSC [1 x SSC is 0.15 M NaCl plus 0.015 M sodium citrate]) was performed for 16 to 48 h. Autoradiograms of the washed membranes allowed recognition of the rotavirus serotype present in the blotted or dotted specimens since each of them hybridized preferentially to one of the four probes. Twenty-four laboratory specimens and 103 clinical specimens from Washington, D.C., Venezuela, and Chile were "serotyped" with this assay. The results were similar to those obtained with a monoclonal antibody serotyping assay.

Immunity to rotaviruses

A potent, multivalent, serotype-specific RV vaccine and improved tests for measuring vaccine potency would help eliminate the necessity to pretest for vaccine efficacy in every country selected for its deployment. Until then, the need will continue for vaccine trials in various countries because the pathogenesis and epidemiology of RV and RV serotypes differ between and within countries. Although RV vaccinology is complex, it has forged ahead of our knowledge of RV immunopathogenesis and epidemiology.

Clinical features of acute infantile gastroenteritis associated with human rotavirus subgroups I and II

During a prospective 3-year study, clinical and epidemiological features of rotavirus gastroenteritis in black infants were investigated. Fever and temperatures exceeding 39 degrees C were more frequent in children shedding subgroup II rotaviruses, whereas vomiting was more pronounced in children with subgroup I infection. Diarrhea, dehydration, duration of illness, and the need for admission to a hospital ward were similar in both groups.

Rotavirus epidemiology in Vellore, south India: group, subgroup, serotype, and electrophoretype

Rotaviruses were detected in 163 of 916 (17.8%) specimens collected from children under 3 years of age with gastroenteritis in Vellore, South India, between August 1983 and July 1985. Rotaviruses were detected throughout the study period, with a peak prevalence in December to February (winter) and June to August (southwest monsoon season). A total of 117 rotavirus strains were tested for subgroup, serotype, and rotavirus double-stranded RNA electrophoretic migration pattern; 24.8% of the strains were subgroup I, 69.2% were subgroup II, and 6.0% were neither subgroup I nor subgroup II. Subgroup I and II strains were circulating concurrently throughout the study. Of the 117 rotavirus strains, 32 (27.4%) were serotyped; 15 were serotype 1, 3 were serotype 2, 2 were serotype 3, and 12 were serotype 4. Three serotypes were circulating concurrently during the periods of peak rotavirus prevalence. In 100 of the 117 strains (85.4%) an RNA pattern was detected. One unusual subgroup I group A rotavirus with a long migration pattern and four atypical rotaviruses serologically related to group C were also detected.

Relative frequencies of rotavirus serotypes 1, 2, 3, and 4 in Venezuelan infants with gastroenteritis

We have used a recently developed monoclonal antibody enzyme-linked immunosorbent assay (K. Taniguchi, T. Urasawa, Y. Morita, H. B. Greenberg, and S. Urasawa, J. Infect. Dis. 155:1159-1166, 1987) for serotyping rotaviruses recovered from 134 Venezuelan infants over a period of 15 months. One hundred and nine of the specimens were typed with the following distribution: serotype 1, 48%; serotype 2, 16%; serotype 3, 22%; and serotype 4, 14%. Three specimens reacted with two different monoclonal antibodies. In addition, 6 specimens (5%) containing enough outer capsid antigen could not be typed; partial RNA sequence analysis of the glycoprotein gene from three of these six strains failed to reveal sequence differences with prototype strains that could be serotyped with the monoclonal antibodies. Variations in the recovery rates of the different serotypes were observed. Serotypes 2, 3, and 4 predominated at the beginning of the study, and serotype 1 predominated at the end of the study. Diarrheal illness appeared to be more prolonged in infants shedding rotavirus serotypes 1 and 3 than in those shedding serotypes 2 and 4.

Characterization of homotypic and heterotypic VP7 neutralization sites of rhesus rotavirus

The gene 9 nucleotide sequence was determined for rhesus rotavirus and each of 14 viral variants selected for their resistance to neutralizing monoclonal antibodies. Each variant contains a single gene 9, VP7, mutation which permits viral growth in the presence of the antibody. Variant mutations were identified in two distinct neutralization regions. Region A was identified by monoclonal antibodies that are involved in both serotype-specific and serotype cross-reactive neutralization. Region C was identified by serotype-specific neutralizing monoclonal antibodies. Heterotypic neutralizing monoclonal antibody 57-8 selected variants with a mutation at amino acid 94 in the A region, the same amino acid location selected by serotype-specific monoclonal antibodies. Monoclonal antibody 3 selected a VP7 mutation at amino acid 99 resulting in additional N-linked glycosylation of the VP7 protein. Despite the added VP7 glycosylation, variant v3 was not broadly resistant to additional VP7-specific neutralizing monoclonal antibodies.

Current approaches to the development of vaccines effective against parainfluenza and respiratory syncytial viruses

Vaccines against parainfluenza (PIV) and respiratory syncytial viruses (RSV) that are currently being developed include both live and subunit vaccines. Candidate live PIV vaccines that have been found to be attenuated and efficacious in rodents or primate models are (1) cold-adapted, temperature-sensitive mutants of PIV-type 3 that have been serially passaged at low temperature (20 degrees C) in simian kidney tissue culture; (2) protease-activation mutants (PIV-1-Sendai), which have mutations that decrease the cleavability of their F glycoprotein by host cell protease; (3) an animal virus, bovine PIV-3 virus, which is antigenically related to the human PIV-3 virus, and (4) vaccinia recombinant viruses bearing RSV or PIV-3 glycoproteins. Subunit RSV and PIV-3 viruses are being produced and evaluated as immunogens. A major concern with these vaccines is the possibility of disease potentiation following virus infection as occurred previously with formalin-inactivated measles and RSV vaccines. Studies indicate that PIV-3 and RSV glycoprotein vaccines are immunogenic and efficacious in animals but insufficient data exist to estimate their capacity to potentiate disease. However, since a cotton rat model is available to detect potentiated disease resulting from infection of cotton rats previously immunized with formalin-inactivated RSV vaccine, it is now possible to systematically evaluate new vaccines in experimental animals for disease potentiation before studies are initiated in humans. It is likely within the next several years that one or more of these PIV or RSV vaccines will be tested in humans for safety and immunogenicity.

Relative concentrations of serum neutralizing antibody to VP3 and VP7 proteins in adults infected with a human rotavirus

Two outer capsid rotavirus proteins, VP3 and VP7, have been found to elicit neutralizing-antibody production, but the immunogenicity of these proteins during human rotavirus infection has not been determined. The relative amounts of serum neutralizing antibody against the VP3 and VP7 proteins of the CJN strain of human rotavirus were, therefore, determined in adult subjects before and after infection with this virus. Reassortant strains of rotavirus that contained the CJN gene segment for only one of these two neutralization proteins were isolated and used for this study. The geometric mean titer of serum neutralizing antibody to a reassortant virus (CJN-M) that contained VP7 of CJN and VP3 of another human rotavirus was 12.7 times less than that of antibody to CJN before infection and 20.3 times less after infection. This indicated that most neutralizing antibody was against the VP3 rather than the VP7 protein of CJN. This result was confirmed with other reassortants between CJN and animal rotavirus strains (EDIM and rhesus rotavirus). These findings suggest that VP3 is the primary immunogen that stimulates neutralizing antibody during at least some rotavirus infections of humans.

Prediction of human rotavirus serotype by nucleotide sequence analysis of the VP7 protein gene

Human rotavirus field isolates were characterized by direct sequence analysis of the gene encoding the serotype-specific major neutralization protein (VP7). Single-stranded RNA transcripts were prepared from virus particles obtained directly from stool specimens or after two or three passages in MA-104 cells. Two regions of the gene (nucleotides 307 through 351 and 670 through 711) which had previously been shown to contain regions of sequence divergence among rotavirus serotypes were sequenced by the dideoxynucleotide method with two different synthetic oligonucleotide primers. The resulting nucleotide sequences were compared with the corresponding sequences from rotaviruses of known serotype (serotype 1, 2, 3, or 4). A total of 25 field isolates and 10 laboratory strains examined by this method exhibited marked sequence identity in both areas of the gene with the corresponding regions of 1 of the 4 reference strains. In addition, the predicted serotype from the sequence analysis correlated in each case with the serotype determined when the rotaviruses were examined by plaque reduction neutralization or reactivity with serotype-specific monoclonal antibodies. These data suggest that as a result of the high degree of sequence conservation observed among rotaviruses of the same serotype, it is possible to predict the serotype of a rotavirus isolate by direct sequence analysis of its VP7 gene.

Live viral vaccines for respiratory and enteric tract diseases

In its programme for accelerated development of vaccines for viral respiratory and enteric tract diseases the WHO has assigned a very high priority to respiratory syncytial virus (RSV), parainfluenza viruses and rotaviruses. There is also some interest in alternative approaches to immunization against influenza viruses because of the failure of inactivated vaccines to provide complete and reasonably durable immunity. Current attempts to develop satisfactorily attenuated viruses for use in prevention of disease caused by the above viral pathogens are described.

Epidemiology of rotavirus subgroups and serotypes in Belem, Brazil: a three-year study

Rotavirus subgroups and serotypes were determined in 61 rotavirus-positive faecal samples obtained from children living in Belém, Brazil, followed up from birth to 3 years of age. Fifty-five (90%) of the specimens were subgrouped and the serotypes of 30 (49%) of them were determined. Subgroup II was detected in 49 (89%) of the 55 subgrouped strains. Serotype 1 was present in 15 (50%) of the 30 serotyped samples; serotypes 2, 3 and 4 were found in 30%, 3.3% and 16.7% respectively, of these specimens. Absence of Vp7, the major outer capsid glycoprotein, did not allow serotyping in 21 (34.4%) of the 61 rotavirus-positive specimens, and an unidentifiable new serotype was found in faeces of one child. In addition, 4 samples were classified as subgroup II serotype 2 (which is very unusual). Twelve (80%) of the 15 serotype 1 (subgroup II) specimens were collected from children (5 of them asymptomatic) during their first year of life. All 9 serotype 2 (subgroups I, II, or not determined) samples were detected during the second and third years of life, 7 (77.8%) of them were related to apparent infections. The 5 serotype 4 (subgroup II) samples were obtained throughout the study period, and were associated with both symptomatic (3 cases) and asymptomatic infections. Thirteen children had more than 1 rotavirus infection. Three had 3 successive infections. In 3 cases, the initial infection (either symptomatic or asymptomatic) caused by serotype 1, was followed by a subsequent diarrhoeic episode associated with serotype 2.