Impact of rotavirus vaccination on diarrheal disease burden of children in South America.

INTRODUCTION: Rotavirus is a leading cause of severe diarrheal disease and death in children under five years of age worldwide. Vaccination is one of the most important public health interventions to reduce this significant burden. AREAS COVERED: This literature review examined vaccination coverage, hospitalization rate, mortality, genotypic distribution, immunogenicity, cost-effectiveness, and risk versus benefit of rotavirus vaccination in children in South America. Nine out of twelve countries in South America currently include a rotavirus vaccine in their national immunization program with coverage rates in 2022 above 90%. EXPERT OPINION: Introduction of the rotavirus vaccination has led to a marked reduction in hospitalizations and deaths from diarrheal diseases in children under 5 years, particularly infants under 1 year, in several South American countries. In Brazil, hospitalizations decreased by 59% and deaths by 21% (30-38% in infants). In Peru, hospitalizations in infants fell by 46% and deaths by 37% (56% in infants). Overall, data suggest that rotavirus vaccination has reduced rotavirus deaths by 15-50% in various South American countries. There is some evidence that immunity wanes after the age of 1-year old. Ongoing surveillance of vaccine coverage and changes in morbidity and mortality is important to maximize protection against this disease.

Effectiveness of Pentavalent Rotavirus Vaccine in Shanghai, China: A Test-Negative Design Study.

OBJECTIVE: To evaluate vaccine effectiveness (VE) of a live oral pentavalent rotavirus vaccine (RotaTeq, RV5) among young children in Shanghai, China, via a test-negative design study. STUDY DESIGN: We consecutively recruited children visiting a tertiary children's hospital for acute diarrhea from November 2021 to February 2022. Information on clinical data and rotavirus vaccination was collected. Fresh fecal samples were obtained for rotavirus detection and genotyping. To evaluate VE of RV5 against rotavirus gastroenteritis among young children, unconditional logistic regression models were conducted to compare ORs for vaccination between rotavirus-positive cases and test-negative controls. RESULTS: A total of 390 eligible children with acute diarrhea were enrolled, including 45 (11.54%) rotavirus-positive cases and 345 (88.46%) test-negative controls. After excluding 4 cases (8.89%) and 55 controls (15.94%) who had received the Lanzhou lamb rotavirus vaccine, 41 cases (12.39%) and 290 controls (87.61%) were included for the evaluation of RV5 VE. After adjustment for potential confounders, the 3-dose RV5 vaccination showed 85% (95% CI, 50%-95%) VE against mild to moderate rotavirus gastroenteritis among children aged 14 weeks to ≤4 years and 97% (95% CI, 83%-100%) VE among children aged 14 weeks to ≤2 years with genotypes G8P8, G9P8, and G2P4 represented 78.95%, 18.42%, and 2.63% of circulation strains, respectively. CONCLUSIONS: A 3-dose vaccination of RV5 is highly protective against rotavirus gastroenteritis among young children in Shanghai. The G8P8 genotype prevailled in Shanghai after RV5 introduction.

Interference Between Enteric Viruses and Live-Attenuated Rotavirus Vaccine Virus in a Healthy Australian Birth Cohort.

BACKGROUND: Rotavirus vaccines have reduced effectiveness in high-mortality settings. Interference between enteric viruses and live-attenuated oral vaccine strains may be a factor. METHODS: In a birth cohort of healthy Australian infants, parents collected weekly stool samples. Three hundred eighty-one paired swabs collected within 10-days of RotaTeq vaccination from 140 infants were tested for 10 enteric viruses and RotaTeq strains. RESULTS: Collectively, both ribonucleic acid and deoxyribonucleic acid viruses were negatively associated with RotaTeq shedding (adjusted odds ratio = 0.29, 95% confidence interval = 0.14-0.58 and adjusted odds ratio = 0.30, 95% confidence interval = 0.11-0.78, respectively). CONCLUSIONS: Enteric viruses may interfere with RotaTeq replication in the gut and thus RotaTeq stool shedding.

Predicting the long-term impact of rotavirus vaccination in 112 countries from 2006 to 2034: A transmission modeling analysis.

Rotavirus vaccination has been shown to reduce rotavirus burden in many countries, but the long-term magnitude of vaccine impacts is unclear, particularly in low-income countries. We use a transmission model to estimate the long-term impact of rotavirus vaccination on deaths and disability adjusted life years (DALYs) from 2006 to 2034 for 112 low- and middle-income countries. We also explore the predicted effectiveness of a one- vs two- dose series and the relative contribution of direct vs indirect effects to overall impacts. To validate the model, we compare predicted percent reductions in severe rotavirus cases with the percent reduction in rotavirus positivity among gastroenteritis hospital admissions for 10 countries with pre- and post-vaccine introduction data. We estimate that vaccination would reduce deaths from rotavirus by 49.1 % (95 % UI: 46.6-54.3 %) by 2034 under realistic coverage scenarios, compared to a scenario without vaccination. Most of this benefit is due to direct benefit to vaccinated individuals (explaining 69-97 % of the overall impact), but indirect protection also appears to enhance impacts. We find that a one-dose schedule would only be about 57 % as effective as a two-dose schedule 12 years after vaccine introduction. Our model closely reproduced observed reductions in rotavirus positivity in the first few years after vaccine introduction in select countries. Rotavirus vaccination is likely to have a substantial impact on rotavirus gastroenteritis and its mortality burden. To sustain this benefit, the complete series of doses is needed.

Incidence of Intussusception in Bamako, Mali, Before and After the Introduction of Rotavirus Vaccine.

Pentavalent rotavirus vaccine has been associated with a small increase in intussusception, but pre- and post-introduction data are lacking in many low-resource settings. Using chart review and prospective surveillance data, intussusception incidence was estimated in Bamako, Mali. The mean annual intussusception incidence post-introduction was not significantly different from that of pre-introduction.

Evolutionary analysis of rotavirus G1P[8] strains from Chennai, South India.

Rotaviruses by virtue of its segmented genome generate numerous genotypes. G1P[8] is the most common genotype reported globally. We intend to identify the evolutionary differences among G1P[8] strains from the study with vaccine strains. Stool samples collected from children <5 years were screened for rotavirus antigen by enzyme linked immunosorbent assay. The samples that tested positive for rotavirus were subjected to VP7 and VP4 semi-nested RT-PCR. Sanger sequencing was performed in randomly chosen VP7 and VP4 rotavirus strains. Phylogenetic analysis showed less homology between study strains and vaccine strains and they were placed in different lineages. The VP7 and VP4 proteins of rotavirus were analyzed by two different platforms to identify the amino acid substitutions in the epitope regions. Nine amino acid substitutions with respect to Rotarix®, RotaTeq® and Rotasiil®-V66A, A/T68S, Q72R, N94S, D100E, T113I, S123N, M217T, and I281T were observed in VP7. There were five amino acid substitutions-S145G, N/D195G, N113D, N/I78T, E150D in VP4 (VP8 portion) with respect to Rotarix® and RotaTeq® vaccine strains. M217T substitution in VP7 (epitope 7-2) and N113D, D195G substitution in VP4 (epitope 8-3, 8-1) confer changes in polarity/electrical charge with respect to vaccine strains, thus indicating the need for continued surveillance.

The Long-Term Impact of Rotavirus Vaccines in Korea, 2008-2020; Emergence of G8P[8] Strain.

This study evaluated the long-term impact of rotavirus vaccination on prevalence, seasonality, and genotype distribution in Gwangju, Korea for 13 seasons. Rotavirus was identified using ELISA and then sequenced for G and P genotypes by Reverse Transcription Polymerase Chain Reactions for diarrhoeagenic patient specimens from local hospitals between January 2008 and August2020. Of 26,902 fecal samples, 2919 samples (10.9%) were ELISA positive. The prevalence declined from 16.3% in pre-vaccine era to 5.4% in post-vaccine era. In the pre-vaccine period, G1P[8] was the most common genotype, followed by G2P[4], G3P[8], and G9P[8], etc. In the transitional period, the proportion of G2P[4] became the dominant genotype and G1P[8] was still commonly identified. In contrast, the novel genotype G8P[8] was predominant in the post-vaccine period. Meanwhile, G2P[4] and G8P[8] were major genotypes in both Rotarix and RotaTeq groups. The substantial decline of G1P[8] prevalence, reemergence of G1P[8], G3P[8], and G2P[4] rotavirus strains, and surge of the rare G8P[8] after vaccine introduction were interesting points to note. The continuous surveillance on the genotypes of RV will be needed to understand rotavirus epidemiology and their evolutionary patterns, as caution is required when interpreting temporal changes in RV genotype dynamic.

Effectiveness of the oral human attenuated pentavalent rotavirus vaccine (RotaTeq™) postlicensure: a meta-analysis-2006-2020.

BACKGROUND: Rotavirus (RV), which causes RV-associated gastroenteritis (RVGE), has accounted for considerable morbidity. We aimed to assess the effectiveness (VE) of the oral pentavalent RV vaccine (RotaTeq™) in real-world settings in children and infants with gastroenteritis. METHODS: We performed a systematic search for peer-reviewed studies published between 1 January 2006 and 1 May 2020 and a meta-analysis to calculate the VE of RotaTeq™ vaccine. The primary outcome was the pooled three-dose vaccine VE. Stratified analysis of the vaccine VEs was performed according to dosages, study design, population age, socioeconomic status (SES), introduction condition, control group types, outcomes of RV disease, and RV strains. RESULTS: After screening 2359 unique records, 28 studies were included and meta-analyzed. The overall VE estimate was 84% (95% confidence interval [CI], 80-87%). Stratified analyses revealed a nonnegligible impact of factors such as study design and SES. Other factors did not show great impart to VE with no significant differences between groups. CONCLUSIONS: RotaTeq™ is effective against RV infection, especially in high-income countries. Adopting suitable study methods and expansion of RV surveillance in low-income regions is crucial to assess VE in real-life settings and provide feasible vaccine regimens to improve vaccine VE.

Australian Rotavirus Surveillance Program: Annual Report, 2018.

ABSTRACT: This report, from the Australian Rotavirus Surveillance Program and collaborating laboratories Australia-wide, describes the rotavirus genotypes identified in children and adults with acute gastroenteritis during the period 1 January to 31 December 2018. During this period, 690 faecal specimens were referred for rotavirus G- and P- genotype analysis, including 607 samples that were confirmed as rotavirus positive. Of these, 457/607 were wild-type rotavirus strains and 150/607 were identified as rotavirus vaccine-like. Genotype analysis of the 457 wild-type rotavirus samples from both children and adults demonstrated that G3P[8] was the dominant genotype nationally, identified in 52% of samples, followed by G2P[4] (17%). The Australian National Immunisation Program, which previously included both RotaTeq and Rotarix vaccines, changed to Rotarix exclusively on 1 July 2017. Continuous surveillance is needed to identify if the change in vaccination schedule could affect rotavirus genotype distribution and diversity in Australia.

Safety profile of rotavirus vaccines among individuals aged ≥8 months of age, United States, vaccine adverse event reporting system (VAERS), 2006-2019.

INTRODUCTION: In 2006 and 2008, two live, oral rotavirus vaccines, RotaTeq (RV5) and Rotarix (RV1), were introduced into the routine immunization program in the United States. A previous rotavirus vaccine, RotaShield, was associated with an increased risk of intussusception, with data suggesting an age-dependent variation in risk. Advisory Committee on Immunization Practices (ACIP) currently recommends that RV5 or RV1 immunization be initiated by age 14 weeks and 6 days and completed by 8 months 0 days. METHODS: We searched for U.S. VAERS reports of RV5, RV1, or unknown rotavirus vaccine brand among individuals aged ≥8 months. We analyzed reports by 2 age groups (individuals aged ≥8 months-≤5 years and ≥6 years), vaccine brand name, adverse event (AE) reported, classification of seriousness (death, non-death serious, and non-serious) and mode of exposure (direct vs. indirect exposure). For serious reports we reviewed available medical records and assigned a primary diagnosis. RESULTS: VAERS received a total of 344 U.S. reports following rotavirus vaccination among individuals ≥8 months of age, 32 (9.3%) were serious. In the younger age-group, 307 (99%) of 309 reports followed direct vaccination of the child. In contrast, in individuals aged ≥6 years, 21 (60%) of 35 reports were via potential indirect exposure to a vaccinated child. The frequently reported AEs in the younger age-group were inappropriate schedule of drug administration 104 (34%) and drug administered to patient of inappropriate age 45 (15%); in the older group these were accidental exposure 9 (26%) and eye irritation 7 (20%). No difference in the safety profile was observed between RV1 and RV5. CONCLUSIONS: We did not identify any unexpected AEs for RV vaccines among individuals aged ≥8 months. Health care providers should adhere to the ACIP recommended schedule and older individuals should apply necessary precautions to prevent potential secondary exposure from vaccinated children.

Genetic Diversity of Human Rotavirus A Among Hospitalized Children Under-5 Years in Lebanon.

Human rotavirus remains a major cause of gastroenteritis worldwide despite the availability of effective vaccines. In this study, we investigated the genetic diversity of rotaviruses circulating in Lebanon. We genetically characterized the VP4 and VP7 genes encoding the outer capsid proteins of 132 rotavirus-associated gastroenteritis specimens, previously identified in hospitalized children (<5 years) from 2011 to 2013 in Lebanon. These included 43 vaccine-breakthrough specimens and the remainder were from non-vaccinated subjects. Phylogenetic analysis of VP4 and VP7 genes revealed distinct clustering compared to the vaccine strains, and several substitutions were identified in the antigenic epitopes of Lebanese specimens. No unique changes were identified in the breakthrough specimens compared to non-breakthroughs that could explain the occurrence of infection in vaccinated children. Further, we report the emergence of a rare P[8] OP354-like strain with a G9 VP7 in Lebanon, possessing high genetic variability in their VP4 compared to vaccine strains. Therefore, human rotavirus strains circulating in Lebanon and globally have accumulated numerous substitutions in their antigenic sites compared to those currently used in the licensed vaccines. The successful spread and continued genetic drift of these strains over time might undermine the effectiveness of the vaccines. The effect of such changes in the antigenic sites on vaccine efficacy remains to be assessed.

The Impact of Human Genetic Polymorphisms on Rotavirus Susceptibility, Epidemiology, and Vaccine Take.

Innate resistance to viral infections can be attributed to mutations in genes involved in the immune response, or to the receptor/ligand. A remarkable example of the latter is the recently described Mendelian trait resistance to clinically important and globally predominating genotypes of rotavirus, the most common agent of severe dehydrating gastroenteritis in children worldwide. This resistance appears to be rotavirus genotype-dependent and is mainly mediated by histo-blood group antigens (HBGAs), which function as a receptor or attachment factors on gut epithelial surfaces. HBGA synthesis is mediated by fucosyltransferases and glycosyltransferases under the genetic control of the FUT2 (secretor), FUT3 (Lewis), and ABO (H) genes on chromosome 19. Significant genotypic and phenotypic diversity of HBGA expression exists between different human populations. This genetic diversity has an effect on genotype-specific susceptibility, molecular epidemiology, and vaccine take. Here, we will discuss studies on genetic susceptibility to rotavirus infection and place them in the context of population susceptibility, rotavirus epidemiology, vaccine take, and public health impact.

Impact of rotavirus vaccine on paediatric rotavirus hospitalisation and intussusception in New Zealand: A retrospective cohort study.

BACKGROUND: Rotavirus results in a significant burden of hospitalisations and deaths globally. Rotavirus vaccine has been used in New Zealand since July 2014. The aim of this study was to assess the safety and effectiveness of RotaTeq® vaccine in New Zealand between 2006 and 2016. METHODS: A national cohort study of 723,695 children aged less than 6 years was carried out using linked administrative datasets. Study outcomes were hospitalisation for intussusception, rotavirus, and all-cause gastroenteritis. Intussusception hospitalisation rates were calculated from 2006 to 2016, and rotavirus and all-cause gastroenteritis hospitalisation rates from 2011 to 2016. We examined the effect of RotaTeq® vaccination on rotavirus and all-cause gastroenteritis hospitalisation rates using Poisson regression. Adjusted incidence rate ratios controlled for sex, year of birth, ethnicity, socioeconomic deprivation, and district health board area. RESULTS: Significant reductions in the incidence of rotavirus hospitalisation were seen in all age groups, ethnicities, and deprivation following the introduction of RotaTeq®. There was a 92.6% reduction in hospitalisation incidence in the vaccinated cohort (p < 0.0001). There was also a 48% reduction in all-cause gastroenteritis hospitalisation incidence in the vaccinated cohort (p < 0.0001). The average annual intussusception rate in children aged less than 3 years was 26.2 per 100,000, with no significant change over time (p = 0.847). CONCLUSIONS: In New Zealand the introduction of RotaTeq® resulted in a significant reduction in rotavirus hospitalisation, and a halving in all-cause gastroenteritis hospitalisation. There has been no change in the overall incidence of intussusception or clear change in patterns of cases, although intussusception cases did occur within risk period immediately post vaccine.

Shedding of oral pentavalent bovine-human reassortant rotavirus vaccine indicates high uptake rate of vaccine and prominence of G-type G1.

BACKGROUND: Live oral pentavalent bovine-human reassortant rotavirus (RV) vaccine, RotaTeq®, contains bovine rotaviruses reassorted with human G-types G1, G2, G3 and G4, and P-type P[8]. Shedding of RotaTeq® vaccine, as studied by RT-PCR, has been shown to be more common than initially reported, and may include formation of vaccine-derived double-reassortant G1P[8] RVs. We studied the extent and duration of RotaTeq® vaccine virus shedding, genotypes shed, and clinical symptoms associated with shedding. MATERIAL AND METHODS: We enrolled a total of 301 infants who received RotaTeq® vaccine according to Finnish schedule at 2, 3 and 5 months of age. Stool samples were collected 5-10 days after the first and 0-7 days before the third dose of the vaccine. Additional stool samples 6 and 12 weeks later were collected if the second stool sample was positive. All stools were studied with RT-PCR for RV VP7, VP4 and VP6. Parents filled a symptom diary for a week after each vaccine dose. RESULTS: We found that 93% of the vaccinees shed vaccine related viral particles in one sample taken 5-10 days after the first dose, indicating that stool shedding is very common and may be regarded as a marker of successful vaccination. Genotype G1 was the predominant genotype in shedding, often in association with P[8], and the only genotype found in long-term shedding. Also G4 was commonly detected whereas other vaccine G-types and bovine-type P[5] were not. CONCLUSIONS: Shedding of RotaTeq® vaccine-derived viruses is a sign for successful vaccination. Intense shedding of G1 with or without P[8]reflects effective multiplication and may be an important factor in the induction of protective immunity. Shedding of G1 containing vaccine viruses may be prolonged up to 8 months of age. These results suggest that the pentavalent vaccine functions largely like a monovalent G1 vaccine. Eudra-CT: 2014-004252-60.

Continuing rotavirus circulation in children and adults despite high coverage rotavirus vaccination in Finland.

OBJECTIVES: To determine occurrence of residual rotavirus (RV) disease in different age groups in Finland after five to nine years of high coverage (≥90%) mass-vaccination with RotaTeqⓇ vaccine, and to examine the vaccine effect on circulating genotypes. METHODS: Since 2013 all clinical laboratories in the country were obliged to send RV positive stool samples for typing. RVs were genotyped by RT-PCR for VP7 and VP4 proteins, sequenced and compared to reference strains. RESULTS: RV continued to circulate throughout the study period at low level with a small increase in 2017-2018. There were three age-related clusters: young children representing primary or secondary vaccine failures, school-age children who may not have been vaccinated, and the elderly. Genotype distribution differed from the pre-vaccination period with a steady decline of G1P[8], emergence of G9P[8] and especially more recently G12P[8]. In the elderly, G2P[4] was predominant but was also replaced by G12P[8] in 2017-18. CONCLUSIONS: RV vaccination with a high coverage keeps RV disease at low level but does not prevent RV circulation. New RV genotypes have emerged replacing largely the previously predominant G1P[8]. Increase of overall RV activity with emergence of G12P[8] in the latest follow-up season 2017-18 might be a potential alarm sign.

Australian Rotavirus Surveillance Program: Annual Report, 2017

This report, from the Australian Rotavirus Surveillance Program and collaborating laboratories Australia-wide, describes the rotavirus genotypes identified in children and adults with acute gastroenteritis during the period 1 January to 31 December 2017. During this period, 2,285 faecal specimens were referred for rotavirus G and P genotype analysis, including 1,103 samples that were confirmed as rotavirus positive. Of these, 1,014/1,103 were wildtype rotavirus strains and 89/1,103 were identified as rotavirus vaccine-like. Genotype analysis of the 1,014 wildtype rotavirus samples from both children and adults demonstrated that G2P[4] was the dominant genotype nationally, identified in 39% of samples, followed by equine-like G3P[8] and G8P[8] (25% and 16% respectively). Multiple outbreaks were recorded across Australia, including G2P[4] (Northern Territory, Western Australia, and South Australia), equine-like G3P[8] (New South Wales), and G8P[8] (New South Wales and Victoria). This year also marks the change in the Australian National Immunisation Program to the use of Rotarix exclusively, on 1 July 2017.

Experiences with rotavirus vaccines: can we improve rotavirus vaccine impact in developing countries?

Rotavirus vaccines have been introduced into over 95 countries globally and demonstrate substantial impact in reducing diarrheal mortality and diarrheal hospitalizations in young children. The vaccines are also considered by WHO as "very cost effective" interventions for young children, particularly in countries with high diarrheal disease burden. Yet the full potential impact of rotavirus immunization is yet to be realized. Large countries with big birth cohorts and where disease burden is high in Africa and Asia have not yet implemented rotavirus vaccines at all or at scale. Significant advances have been made demonstrating the impact of the vaccines in low- and lower-middle income countries, yet the modest effectiveness of the vaccines in these settings is challenging. Current research highlights these challenges and considers alternative strategies to overcome them, including alternative immunization schedules and host factors that may inform us of new opportunities.

Post-licensure experience with rotavirus vaccination in Latin America and the Caribbean: a systematic review and meta-analysis.

INTRODUCTION: Latin American countries were among the first to adopt rotavirus vaccines into national immunization programs; we reviewed one decade of their experience with rotavirus vaccination. AREAS COVERED: We systematically reviewed manuscripts published January 1990-January 2018 to assess rotavirus vaccine effectiveness (VE) via meta-analysis; describe trends in rotavirus and acute gastroenteritis (AGE)-associated hospitalizations and mortality before and after vaccine introduction; and estimate annual hospitalizations and deaths averted by rotavirus vaccination in Latin American and Caribbean children <5 years. Rotavirus vaccines demonstrated VE against rotavirus hospitalization of 76% (95% CI: 58-87) in low-mortality countries and 67% (95% CI: 54-76) in high-mortality countries for children <1 year of age. Reductions of 64.0% (interquartile range (IQR): 49.9-69.2) were observed in rotavirus hospitalizations, 32.8% (IQR 29.0-40.3) in AGE hospitalizations, and 53.5% (IQR: 40.4-57.1) in AGE-related mortalities in children <5 years. In 2015, an estimated 125,000 rotavirus-associated hospitalizations and 800 rotavirus-related deaths were prevented in countries that implemented rotavirus vaccines. EXPERT COMMENTARY: Rotavirus vaccines remain an effective tool against diarrheal disease. The continued success of rotavirus vaccines provides evidence for adoption in Latin American and Caribbean countries that have not yet introduced it, and improvement within those with low coverage.

A decade of experience with rotavirus vaccination in the United States - vaccine uptake, effectiveness, and impact.

INTRODUCTION: Prior to 2006, nearly every U.S. child was infected with rotavirus by 5 years of age, and rotavirus was the leading cause of severe childhood gastroenteritis. In February 2006 and June 2008, the Advisory Committee on Immunization Practices recommended a live attenuated pentavalent rotavirus vaccine (RV5) and a monovalent rotavirus vaccine (RV1), respectively, for routine vaccination of infants in the United States. AREAS COVERED: We reviewed U.S. data on coverage, vaccine effectiveness (VE), and vaccine impact from 2006 to 2017. National rotavirus vaccine coverage estimates increased since vaccine introduction but plateaued at 71-75% in 2013-2015, a level 15-20% lower than that of other routine childhood vaccines. Pooled VE of full series RV5 and RV1 against rotavirus-associated hospitalizations and emergency department visits were 84% (95% CI: 80-87%) and 83% (95% CI: 72-89%), respectively. Vaccine introduction resulted in a median decline in rotavirus-associated hospitalizations and emergency department visits of 80% and 57%, respectively, along with indirect protection of unvaccinated age groups and a decrease in health-care costs. A biennial pattern in rotavirus detection emerged post-vaccine implementation. EXPERT COMMENTARY: The increasing use of rotavirus vaccines has substantially diminished the burden and changed the epidemiology of rotavirus disease in U.S. children; efforts to increase rotavirus vaccine coverage should continue.

Monitoring Shedding of Five Genotypes of RotaTeq Vaccine Viruses by Genotype-Specific Real-Time Reverse Transcription-PCR Assays.

RotaTeq (RV5) is a widely used live attenuated pentavalent rotavirus (RV) vaccine. Although fecal shedding of RV vaccine strains persists for long time periods, it is unclear how each vaccine strain replicates in intestinal tissue and is excreted in stool. To examine this issue, we established RV5 genotype-specific real-time reverse transcription-PCR (RT-PCR) assays. Five real-time RT-PCR assays were designed for the VP7 gene in genotypes G1, G2, G3, G4, and G6. All assays exhibited excellent linearity, and the detection limit was 1 infectious unit (IU)/reaction for G2, G4, and G6 and 10 IUs/reaction for G1 and G3. No cross-reactivity was observed among G genotypes. The inter- and intra-assay coefficients of variation were less than 3%. The assays were used to examine 129 stool samples collected from eight infants who received RV5. In cases 1 and 2, who received three rounds of vaccination, RV shedding decreased gradually with the number of vaccinations. G1 and G6 shedding appeared to be predominant in comparison to shedding of the other genotypes. Patterns of fecal shedding of the five genotypes of vaccine viruses differed between the eight vaccine recipients. RV5 genotype-specific real-time RT-PCR assays will be useful to study the molecular biology of RV5 replication in infants and experimental animals.