Vaccines for rotavirus gastroenteritis universally needed for infants

A disease severity scale for the evaluation of vaccine and other preventive or therapeutic interventions for travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea (TD) is the most common travel-related illness with an estimated 10 million people afflicted annually. Outcome measures to assess the efficacy of primary and secondary TD interventions were historically based on diarrhoea frequency with ≥1 associated gastrointestinal symptom. Furthermore, efficacy determination is often made on the presence or absence of TD, rather than on TD illness severity. Current severity classifications are based on subjective consideration of impact of illness on activity. We sought to develop a standardized scoring system to characterize TD severity to potentially apply as a secondary outcome in future field studies.

METHODS

Data on multiple signs and symptoms were obtained from a previously published multisite TD treatment trial conducted by the US Department of Defense (TrEAT TD). Correlation, regression and multiple correspondence analyses were performed to assess impact on activity and a TD severity score was established.

RESULTS

Numerous signs and symptoms were associated with impaired function, with malaise and nausea most strongly associated [odds ratio (OR) 5.9-44.3, P < 0.0001 and OR 2.8-37.1, P < 0.0001, respectively). Based on co-varying symptomatology, a TD severity score accounting for diarrhoea frequency in addition to several signs and symptoms was a better predictor of negative impact on function than any single sign/symptom (X2 = 127.16, P < 0.001). Additionally, there was a significant difference (P < 0.0001) in the mean TD severity score between those with acute watery diarrhoea (3.9 ± 1.9) and those with dysentery or acute febrile illness (6.2 ± 2.0).

CONCLUSIONS

The newly developed disease severity score better predicted a negative impact on activity due to TD than did any single sign or symptom. Incorporating multiple parameters into the TD severity score better captures illness severity and moves the field towards current recommendations for TD management by considering symptoms with high functional impact. Further validation of this score is needed in non-military travellers and other settings.

Pre-vaccine circulating group a rotavirus strains in under 5 years children with acute diarrhea during 1999-2013 in Cameroon

The aim of this review was to assess all the studies on rotavirus G and P characterization during the pre-vaccine period (1999-2013) in Cameroon to have a better basis for post-vaccine introduction evaluations. A retrospective study was done through a comprehensive review of published (PubMed, Google Scholar) and accessible unpublished data on rotavirus G and P genotypes circulating in five regions of Cameroon. Descriptive data were expressed as frequencies tables and proportions. A total of 1844 rotavirus positive cases were analyzed. In all, 1534 strains were characterized for the P (VP4) specificity. Six different VP4 genotypes were observed, including P [4], P [6], P [8], P [9], P [10] and P [14]. The most predominant P genotypes were P [8] at 42.6%, and P [6] at 37.9%. Mixed infections were observed at 5.3%, whereas 4.1% of the strains were P non-typeable. A total of 1518 rotavirus strains were characterized for the G (VP7) specificity. VP7 genotypes G1, G2, G3, G4, G5, G6, G8, G9, G10 and G12 were observed. G1 (35.3%), G3 (19.5%), G2 (14.9%) and G12 (10.1%) were the predominant G genotypes while G5 and G10 were least prevalent at 0.06% each. Approximately 5.1% of all strains were G non-typeable whereas 5.3% were mixed G genotypes. A total of 1472 strains were characterized for both G and P genes, from which 38 different G-P combinations were observed. Overall, G1P [8] (22%) was identified as the predominant rotavirus strain circulating in Cameroon followed by G3P [6] (15%). In conclusion, we observed that the genotypes identified in Cameroon during 1999-2013 were partially covered by the two WHO recommended rotavirus vaccines. This review provides comprehensive up-to-date information on rotavirus strain surveillance in Cameroon during the pre-vaccination era.

Anti-Infectious Human Vaccination in Historical Perspective

A brief history of vaccination is presented since the Jenner's observation, through the first golden age of vaccinology (from Pasteur's era to 1938), the second golden age (from 1940 to 1970), until the current period. In the first golden age, live, such as Bacille Calmette Guérin (BCG), and yellow fever, inactivated, such as typhoid, cholera, plague, and influenza, and subunit vaccines, such as tetanus and diphtheria toxoids, have been developed. In the second golden age, the cell culture technology enabled polio, measles, mumps, and rubella vaccines be developed. In the era of modern vaccines, in addition to the conjugate polysaccharide, hepatitis A, oral typhoid, and varicella vaccines, the advent of molecular biology enabled to develop hepatitis B, acellular pertussis, papillomavirus, and rotavirus recombinant vaccines. Great successes have been achieved in the fight against infectious diseases, including the smallpox global eradication, the nearly disappearance of polio, the control of tetanus, diphtheria, measles, rubella, yellow fever, and rabies. However, much work should still be done for improving old vaccines, such as BCG, anthrax, smallpox, plague, or for developing effective vaccines against old or emerging infectious threats, such as human-immunodeficiency-virus, malaria, hepatitis C, dengue, respiratory-syncytial-virus, cytomegalovirus, multiresistant bacteria, Clostridium difficile, Ebola virus. In addition to search for innovative and effective vaccines and global infant coverage, even risk categories should adequately be protected. Despite patients under immunosuppressive therapy are globally increasing, their vaccine coverage is lower than recommended, even in developed and affluent countries.

Pharmacoeconomic spotlight on rotavirus vaccine RIX4414 (Rotarix™) in developed countries

The most common cause of severe diarrhea in infants and young children is rotavirus gastroenteritis (RVGE), which is associated with significant morbidity, healthcare resource use, and direct and indirect costs in industrialized nations. The monovalent rotavirus vaccine RIX4414 (Rotarix™) is administered as a two-dose oral series in infants and has demonstrated protective efficacy against RVGE in clinical trials conducted in developed countries. In addition, various naturalistic studies have demonstrated ‘real-world’ effectiveness after the introduction of widespread rotavirus vaccination programs in the community setting.

Numerous cost-effectiveness analyses have been conducted in developed countries in which a universal rotavirus vaccination program using RIX4414 was compared with no universal rotavirus vaccination program. There was a high degree of variability in base-case results across studies even when the studies were conducted in the same country, often reflecting differences in the selection of data sources or assumptions used to populate the models. In addition, results were sensitive to plausible changes in a number of key input parameters. As such, it is not possible to definitively state whether a universal rotavirus vaccination program with RIX4414 is cost effective in developed countries, although results of some analyses in some countries suggest this is the case. In addition, international guidelines advocate universal vaccination of infants and children against rotavirus. It is also difficult to draw conclusions regarding the cost effectiveness of rotavirus vaccine RIX4414 relative to that of the pentavalent rotavirus vaccine, which is administered as a three-dose oral series. Although indirect comparisons in cost-effectiveness analyses indicate that RIX4414 provided more favorable incremental cost-effectiveness ratios when each vaccine was compared with no universal rotavirus vaccination program, results were generally sensitive to vaccine costs. Actual tender prices of a full vaccination course for each vaccine were not known at the time of the analyses and therefore had to be estimated.

Pharmacoeconomic spotlight on rotavirus vaccine RIX4414 (Rotarix™) in the prevention of rotavirus gastroenteritis in developing countries

This article provides an overview of the clinical profile of rotavirus vaccine RIX4414 (Rotarix™) in the prevention of rotavirus gastroenteritis (RVGE) in developing countries, followed by a review of pharmacoeconomic analyses with the vaccine in low- and middle-income countries. RVGE is associated with significant morbidity and mortality among children <5 years of age in developing countries. The protective efficacy of a two-dose oral series of rotavirus vaccine RIX4414 has been demonstrated in several well designed clinical trials conducted in developing countries, and the 'real-world' effectiveness of the vaccine has also been shown in naturalistic and case-control trials after the introduction of universal vaccination programs with RIX4414 in Latin American countries. The WHO recommends universal rotavirus vaccination programs for all countries. Numerous modelled cost-effectiveness analyses have been conducted with rotavirus vaccine RIX4414 across a wide range of low- and middle-income countries. Although data sources and assumptions varied across studies, results of the analyses consistently showed that the introduction of the vaccine as part of a national vaccination program would be very cost effective compared with no rotavirus vaccination program, according to widely used cost-effectiveness thresholds for developing countries. Vaccine price was not known at the time the analyses were conducted and had to be estimated. In sensitivity analyses, rotavirus vaccine RIX4414 generally remained cost effective at the highest of a range of possible vaccine prices considered. Despite these favorable results, decisions regarding the implementation of universal vaccination programs with RIX4414 may also be contingent on budgetary and other factors, underscoring the importance of subsidized vaccination programs for poor countries through the GAVI Alliance (formerly the Global Alliance for Vaccines and Immunization).

Measuring the Impact of Rotavirus Acute Gastroenteritis Episodes (MIRAGE): A prospective community-based study

BACKGROUND

Current assessments of the burden of rotavirus (RV)-related gastroenteritis are needed to evaluate the potential benefits of RV immunization interventions. The objective of the present study was to characterize the burden of RV gastroenteritis among children presenting in outpatient settings with gastroenteritis.

METHODS

Between January and June 2005, 395 children younger than three years of age presenting with gastroenteritis symptoms (at least three watery or looser-than-normal stools, or forceful vomiting within the previous 24 h period) were recruited from 59 Canadian clinics and followed for two weeks. Stool specimens were tested for the RV antigen. Gastroenteritis-related symptoms, health care utilization, parental work loss and other cases of gastroenteritis in the household were assessed by questionnaires and daily symptom cards that were completed by caregivers.

RESULTS

Of 336 conclusive test results, 55.4% were RV positive (RV+). In addition to diarrhea, 67.2% and 89.3% of RV+ children experienced fever or vomiting, respectively. Compared with RV-negative (RV-) children, RV+ children were more likely to experience the three symptoms concurrently (57.0% versus 26.7%; P<0.001), to be hospitalized (12.9% versus 3.9%; P=0.008) and to induce parental work loss (53.8% versus 37.3%; P=0.003). The median duration of gastroenteritis was eight days for RV+ children (nine days for RV- children). Additional cases of gastroenteritis were present in 46.8% of households in the RV+ group (51.3% of households in the RV- group).

CONCLUSIONS

RV gastroenteritis cases were more severe than other gastroenteritis cases, were hospitalized more often and were associated with considerably more work loss.

Rotavirus vaccine RIX4414 (Rotarix™): a pharmacoeconomic review of its use in the prevention of rotavirus gastroenteritis in developing countries

This article provides an overview of the clinical profile of rotavirus vaccine RIX4414 (Rotarix™) in the prevention of rotavirus gastroenteritis (RVGE) in developing countries, followed by a comprehensive review of pharmacoeconomic analyses with the vaccine in low- and middle-income countries. RVGE is associated with significant morbidity and mortality among children <5 years of age in developing countries. The protective efficacy of a two-dose oral series of rotavirus vaccine RIX4414 has been demonstrated in several well designed clinical trials conducted in developing countries, and the 'real-world' effectiveness of the vaccine has also been shown in naturalistic and case-control trials after the introduction of universal vaccination programmes with RIX4414 in Latin American countries. The WHO recommends universal rotavirus vaccination programmes for all countries. Numerous modelled cost-effectiveness analyses have been conducted with rotavirus vaccine RIX4414 across a wide range of low- and middle-income countries. Although data sources and assumptions varied across studies, results of the analyses consistently showed that the introduction of the vaccine as part of a national vaccination programme would be very (or highly) cost effective compared with no rotavirus vaccination programme, according to widely used cost-effectiveness thresholds for developing countries. Vaccine price was not known at the time the analyses were conducted and had to be estimated. In sensitivity analyses, rotavirus vaccine RIX4414 generally remained cost effective at the highest of a range of possible vaccine prices considered. Despite these favourable results, decisions regarding the implementation of universal vaccination programmes with RIX4414 may also be contingent on budgetary and other factors, underscoring the importance of subsidized vaccination programmes for poor countries through the GAVI Alliance (formerly the Global Alliance for Vaccines and Immunization).

Rotavirus vaccine RIX4414 (Rotarix™): a pharmacoeconomic review of its use in the prevention of rotavirus gastroenteritis in developed countries

The most common cause of severe diarrhoea in infants and young children is rotavirus gastroenteritis (RVGE), which is associated with significant morbidity, healthcare resource use and direct and indirect costs in industrialized nations. The monovalent rotavirus vaccine RIX4414 (Rotarix™) is administered as a two-dose oral series in infants and has demonstrated protective efficacy against RVGE in clinical trials conducted in developed countries. In addition, various naturalistic studies have demonstrated 'real-world' effectiveness after the introduction of widespread rotavirus vaccination programmes in the community setting. Numerous cost-effectiveness analyses have been conducted in developed countries in which a universal rotavirus vaccination programme using RIX4414 was compared with no universal rotavirus vaccination programme. There was a high degree of variability in base-case results across studies even when conducted in the same country, often reflecting differences in the selection of data sources or assumptions used to populate the models. In addition, results were sensitive to plausible changes in a number of key input parameters. As such, it is not possible to definitively state whether a universal rotavirus vaccination programme with RIX4414 is cost effective in developed countries, although results of some analyses in some countries suggest this is the case. In addition, international guidelines advocate universal vaccination of infants and children against rotavirus. It is also difficult to draw conclusions regarding the cost effectiveness of rotavirus vaccine RIX4414 relative to that of the pentavalent rotavirus vaccine, which is administered as a three-dose oral series. Although indirect comparisons in cost-effectiveness analyses indicate that RIX4414 provided more favourable incremental cost-effectiveness ratios when each vaccine was compared with no universal rotavirus vaccination programme, results were generally sensitive to vaccine costs. Actual tender prices of a full vaccination course for each vaccine were not known at the time of the analyses and therefore had to be estimated.

Pentavalent rotavirus vaccine (RotaTeq): a review of its use in the prevention of rotavirus gastroenteritis in Europe

In Europe, rotavirus gastroenteritis is associated with a significant health, economic and social burden, as it is responsible for large numbers of hospitalizations and other healthcare encounters among infants and children, as well as numerous days of work lost by parents and caregivers. RotaTeq is a three-dose, orally administered, live, pentavalent human-bovine reassortant rotavirus vaccine used for the active immunization of infants for prevention of rotavirus gastroenteritis. The protective efficacy of RotaTeq has been evaluated in terms of its effects on the incidence of rotavirus gastroenteritis and on healthcare resource use. Clinical trial data from REST (a randomized, double-blind, placebo-controlled, multinational study in approximately 70,000 healthy infants aged 6-12 weeks) and various subgroup analyses, including a large European cohort, have shown that RotaTeq may be administered at the same time as various other routine vaccines, has high and sustained efficacy covering the main period of risk for rotavirus gastroenteritis, has early protective efficacy after the first and second doses, reduces rotavirus gastroenteritis-associated hospitalization and emergency department and physician visits, and is generally well tolerated. Moreover, RotaTeq has demonstrated efficacy against the five most prevalent serotypes of rotavirus in Europe (G1-G4, G9), in terms of reductions in associated healthcare resource use. There is also evidence that the widespread use of RotaTeq may provide herd immunity, as it appears to have indirect benefits in older, unvaccinated children. Reports on the 'real world' effectiveness of RotaTeq in Europe are just emerging, but data from the US have shown a rapid and marked reduction in rotavirus burden nationwide during the approximately 2-year period following the introduction of RotaTeq and the subsequent availability of official recommendations advocating universal use of the vaccine as part of routine childhood immunization. Similar benefits have also been demonstrated in Australia after the introduction of a publicly funded rotavirus vaccination programme. Postmarketing surveillance data from the US have not identified any concerns, such as an association with intussusception or Kawasaki disease, related to the safety of RotaTeq. In conclusion, RotaTeq is a generally well tolerated vaccine that has efficacy against the five most prevalent serotypes of rotavirus in Europe and provides sustained efficacy over the main risk period for rotavirus gastroenteritis in infants and children, reducing hospitalizations and emergency department visits by decreasing the incidence and severity of illness.

Prospective study of the burden of acute gastroenteritis and rotavirus gastroenteritis in children less than 5 years of age, in Padova, Italy

BACKGROUND

Data on the burden of rotavirus gastroenteritis in Europe are needed to help understand the potential impact of introducing new rotavirus vaccines.

MATERIALS AND METHODS

As part of prospective observational study (Rotavirus gastroenteritis Epidemiology and Viral types in Europe Accounting for Losses in Public Health and Society Study, REVEAL) conducted in 2004--2005 in seven European countries, we studied, the characteristics of acute gastroenteritis and rotavirus gastroenteritis in children less than 5 years in primary care, emergency room and hospital settings (Padova, Italy).

RESULTS

A total of 757 children with acute gastroenteritis were included and enzyme-linked immunoabsorbent assay (ELISA) results were available for 725 cases. The overall estimated annual incidence for rotavirus gastroenteritis was 4.7%. Overall, rotavirus gastroenteritis was estimated to account for 43.6% of acute gastroenteritis cases. Among children with acute gastroenteritis (AGE) aged 6-23 months, 61.2% were rotavirus positive. Rotavirus gastroenteritis (RVGE) was responsible for 68.8% of hospitalizations, 61% of emergency consultations, and 33% of primary care consultations. The most prevalent serotype was G9 (84.4%) followed by G1 (11.8%). The relative risk for rotavirus gastroenteritis of being referred to hospital after an initial consultation in primary care was 3.37 (95% CI: 1.77-6.43) and 3.38 (95% CI: 2.28-5.01) for emergency room referral. Children with rotavirus gastroenteritis generally had more severe disease than children with rotavirus-negative gastroenteritis.

CONCLUSION

Rotavirus accounts for a significant proportion of acute gastroenteritis cases in children less than 5 years in Italy, many of whom require frequent primary care consultations, or care in emergency room or hospital settings.

Cost-effectiveness analysis of vaccination against rotavirus with RIX4414 in France

BACKGROUND

It is estimated that annually 300 000 cases of rotavirus-induced gastroenteritis (RVGE) occur in children aged up to 5 years in France. A two-dose vaccine against rotavirus infection (RIX4414; Rotarix, GlaxoSmithKline), has been shown to be highly effective against severe RVGE.

OBJECTIVE

This study evaluated the cost effectiveness of general vaccination against rotavirus using RIX4414 in France.

METHODS

A Markov model simulated RVGE events and the associated outcomes and costs relating to general vaccination of infants against rotavirus infection using RIX4414 (Rotarix) in a birth cohort of children aged up to 5 years in France with a combined adjustment for age distribution with the seasonality of the infection. Costs and outcomes were estimated from a limited societal perspective, including direct medical costs paid out of pocket or by third-party payers, as well as the proportion of direct medical costs reimbursed by the health authorities. Indirect costs were not included in the base-case analysis. The primary outcome measure was the incremental cost per QALY.

RESULTS

Vaccination with RIX4414 incurred an incremental cost of 44 583 Euro per QALY at a public price of 57 Euro per vaccine dose. Univariate sensitivity analyses showed that the parameters with the largest influence on the results were the transition probabilities of severe diarrhoea, seeking medical advice and emergency visits, utility scores of diarrhoea (mild) in children and infants, and the discount rate for benefits. Probabilistic multivariate sensitivity analysis confirmed these results. The acceptability curve indicated that 94% of the results were under an informal threshold of 50 000 Euro per QALY. Comparing our results with those of a recently published study using pooled data for two rotavirus vaccine products in France, the main differences are explained by differences in model structure and in data input values. They include a different age distribution of the infection, shorter duration of the at-risk period (3 years instead of 5 years), different vaccine efficacy, different unit cost data, different disease duration, and different disutility values for the health states in the model. There is a need for agreed standards to improve comparability of results from different studies.

CONCLUSIONS

The results demonstrate that a generalized vaccination strategy with RIX4414 would be cost effective in France from a limited societal perspective, depending on the baseline assumptions for disease progression and on utility scores selected.

Burden of rotavirus gastroenteritis and potential benefits of a pentavalent rotavirus vaccination in Belgium

OBJECTIVE AND METHODS

A decision analytic model was built to assess the paediatric rotavirus gastroenteritis (RVGE) burden and potential benefits associated with the introduction of RotaTeq (pentavalent rotavirus vaccine) in Belgium.

RESULTS

In the absence of a rotavirus (RV) immunisation programme, paediatric RVGE was estimated to account for about 5,860 hospitalisations, 1,720 cases of nosocomial infections, 9,410 cases treated by general practitioners/paediatricians (GP/P) and 10,790 cases not seeking medical care for a birth cohort followed up to 5 years of age. Paediatric RVGE was estimated to cost about euro9.0 million from the Belgian healthcare provider perspective and euro15.3 million to society. Given a 90% RV vaccination coverage rate, the pentavalent RV vaccine would have a high impact on RV burden by preventing more than 4,850 hospitalisations, 995 cases of nosocomial infections, 7,145 cases treated by GP/P and 8,190 cases not seeking medical care, and reduce RVGE costs by euro7.1 million from the Belgian healthcare provider perspective and euro12.0 million to society.

Rotavirus vp7 antigen produced by Lactococcus lactis induces neutralizing antibodies in mice

AIMS

To determine if live recombinant Lactococcus lactis strains expressing rotavirus VP7 antigen are immunogenic in mice.

METHODS AND RESULTS

Using the food-grade lactic acid bacterium L. lactis as a carrier, we expressed VP7, the major rotavirus outer shell protein and one of the main components of the infective particle, as a cytoplasmic, secreted or cell wall anchored forms. Our results showed that recombinant L. lactis strains secreting VP7 proved to be more immunogenic than strains containing the antigen in the cytoplasm or anchored to the cell wall.

CONCLUSIONS

This is the first demonstration that recombinant L. lactis producing VP7 can induce the production of a neutralizing antibody response against rotavirus by the intragastric route.

SIGNIFICANCE AND IMPACT OF THE STUDY

Rotaviruses are the single most important aetiological agents of severe diarrhoea of infants and young children worldwide and have been estimated to be responsible for 650 000-800 000 deaths per year of children younger than 5 years old in development countries. Thus, the development of a safe and effective vaccine has been a global public health goal. Although two of five mice orally inoculated with L. lactis strains secreting VP7 elicited a specific-antibody response, these strains could be very useful to be used as a prototype to develop a new generation of protective rotavirus vaccines.

Safety and efficacy of a pentavalent human-bovine (WC3) reassortant rotavirus vaccine

BACKGROUND

Rotavirus is a leading cause of childhood gastroenteritis and death worldwide.

METHODS

We studied healthy infants approximately 6 to 12 weeks old who were randomly assigned to receive three oral doses of live pentavalent human-bovine (WC3 strain) reassortant rotavirus vaccine containing human serotypes G1, G2, G3, G4, and P[8] or placebo at 4-to-10-week intervals in a blinded fashion. Active surveillance was used to identify subjects with serious adverse and other events.

RESULTS

The 34,035 infants in the vaccine group and 34,003 in the placebo group were monitored for serious adverse events. Intussusception occurred in 12 vaccine recipients and 15 placebo recipients within one year after the first dose including six vaccine recipients and five placebo recipients within 42 days after any dose (relative risk, 1.6; 95 percent confidence interval, 0.4 to 6.4). The vaccine reduced hospitalizations and emergency department visits related to G1-G4 rotavirus gastroenteritis occurring 14 or more days after the third dose by 94.5 percent (95 percent confidence interval, 91.2 to 96.6 percent). In a nested substudy, efficacy against any G1-G4 rotavirus gastroenteritis through the first full rotavirus season after vaccination was 74.0 percent (95 percent confidence interval, 66.8 to 79.9 percent); efficacy against severe gastroenteritis was 98.0 percent (95 percent confidence interval, 88.3 to 100 percent). The vaccine reduced clinic visits for G1-G4 rotavirus gastroenteritis by 86.0 percent (95 percent confidence interval, 73.9 to 92.5 percent).

CONCLUSIONS

This vaccine was efficacious in preventing rotavirus gastroenteritis, decreasing severe disease and health care contacts. The risk of intussusception was similar in vaccine and placebo recipients. (ClinicalTrials.gov number, NCT00090233.)

Genetic variation ofNSP1 andNSP4 genes among serotype G9 rotaviruses causing hospitalization of children in Melbourne, Australia, 1997–2002

Serotype G9 rotaviruses have emerged as one of the leading causes of gastroenteritis in children worldwide. We examined 29 representative G9 rotavirus isolates from a 6-year collection (1997-2002) and determined the level of variation in genes encoding non-structural proteins, NSP1 and NSP4. Northern hybridization analysis with a whole genome probe derived from the prototype G9 strain, F45, revealed that the NSP1 gene (gene 5) of two isolates (R1 and R14) did not exhibit significant homology. Complementary DNA probes of R1 and R14 genes 5 were used in Northern blot hybridization and indicated the presence of at least two gene 5 alleles among Melbourne G9 rotaviruses. Nucleotide sequence analysis revealed that isolates carrying the R14 gene 5 shared 94-98% sequence identities with one another, while sequence identity to R1 was 78%. Surprisingly, R1 displayed 96% nucleotide identity with the prototype serotype G1 strain, Wa. The detection of different alleles of NSP1 genes prompted us to investigate the level of variation in another non-structural protein, NSP4, a multifunctional protein and the first viral-encoded enterotoxin. Phylogenetic analysis indicated that while all isolates clustered into one group containing the Wa NSP4 allele (genotype 1), isolate R1 was most closely related to Wa. This study reveals new information about the diversity of non-structural proteins of G9 rotaviruses.

A live attenuated vaccine for Lassa fever made by reassortment of Lassa and Mopeia viruses

Lassa virus (LASV) and Mopeia virus (MOPV) are closely related Old World arenaviruses that can exchange genomic segments (reassort) during coinfection. Clone ML29, selected from a library of MOPV/LASV (MOP/LAS) reassortants, encodes the major antigens (nucleocapsid and glycoprotein) of LASV and the RNA polymerase and zinc-binding protein of MOPV. Replication of ML29 was attenuated in guinea pigs and nonhuman primates. In murine adoptive-transfer experiments, as little as 150 PFU of ML29 induced protective cell-mediated immunity. All strain 13 guinea pigs vaccinated with clone ML29 survived at least 70 days after LASV challenge without either disease signs or histological lesions. Rhesus macaques inoculated with clone ML29 developed primary virus-specific T cells capable of secreting gamma interferon in response to homologous MOP/LAS and heterologous MOPV and lymphocytic choriomeningitis virus. Detailed examination of two rhesus macaques infected with this MOPV/LAS reassortant revealed no histological lesions or disease signs. Thus, ML29 is a promising attenuated vaccine candidate for Lassa fever.

Yeast expression of the VP8* fragment of the rotavirus spike protein and its use as immunogen in mice

The VP8* fragment from the rotavirus spike protein was expressed as a fusion protein with two different cell wall proteins of Saccharomyces cerevisiae, Icwp (Ssr1p) and Pir4, to achieve cell wall targeting or secretion to the growth medium of the fusion proteins. Two different host strains were used for the expression of the fusion proteins, a standard S. cerevisiae strain and a mnn9 glycosylation deficient strain, the later to reduce hyper-glycosylation. The Icwp-VP8* fusion could only be detected in the growth medium, indicating that the presence of the VP8* moiety interferes with the anchorage of Icwp to the cell wall. In the case of the Pir4-VP8* fusion proteins, we achieved cell wall targeting or secretion depending on how the gene fusion had been performed. In all cases, the fusion proteins expressed in the mnn9 strain showed a reduced level of glycosylation. Mice were inoculated intraperitoneally either with Pir4-VP8* or Icwp-VP8* fusion proteins purified from the growth medium of mnn9 strains expressing them or with whole cells of an mnn9 strain expressing a Pir4-VP8 fusion protein on its cell walls. Hundred percent of mice inoculated with the Pir4-VP8* fusion protein and 25% of those inoculated with the Icwp-VP8* fusion protein showed high titers of anti-VP8* antibodies. No specific immune response was detected in those mice inoculated with whole cells. Finally, susceptibility to rotavirus infection of the offspring of immunized dams was determined and protection was found in a percentage of approximately 60% with respect to the control group.