Development of candidate rotavirus vaccines derived from neonatal strains in India

T cell epitope based vaccine design while targeting outer capsid proteins of rotavirus strains infecting neonates: an immunoinformatics approach

Gastrointestinal diarrhea is majorly caused by the rotavirus (RV) in the children who generally are under the age group of 5 years. WHO estimates that ∼95% of the children contract RV infection, by this age. The disease is highly contagious; notably in many cases, it is proven fatal with high mortality rates especially in the developing countries. In India alone, an estimated 145,000 yearly deaths occurs due to RV related gastrointestinal diarrhea. WHO pre-qualified vaccines that are available for RV are all live attenuated vaccines with modest efficacy range between 40 and 60%. Further, the risk of intussusceptions has been reported in some children on RV vaccination. Thus, in a quest to develop alternative candidate to overcome challenges associated with these oral vaccines, we chose immunoinformatics approach to design a multi-epitope vaccine (MEV) while targeting the outer capsid viral proteinsVP4 and VP7 of the neonatal strains of rotavirus. Interestingly, ten epitopes, that is, six CD8+T-cells and four CD4+T-cell epitopes were identified which were predicted to be antigenic, non-allergic, non-toxic and stable. These epitopes were then linked to adjuvants, linkers, and PADRE sequences to create a multi-epitope vaccine for RV. The in silico designed RV-MEV and human TLR5 complex displayed stable interactions during molecular dynamics simulations. Further, the immune simulation studies of RV-MEV corroborated that the vaccine candidate emerges as a promising immunogen. Future investigations while performing in vitro and in vivo analyses with designed RV-MEV construct are highly desirable to warrant the potential of this vaccine candidate in protective immunity against different strains of RVs infecting neonates.Communicated by Ramaswamy H. Sarma.

Whole-genome characterization of common rotavirus strains circulating in Vellore, India from 2002 to 2017: emergence of non-classical genomic constellations

Rotaviruses (RVs) are the most common etiological agent of acute gastroenteritis among young children, even after vaccine introduction in low-income countries. A whole-genome classification representing the 11 RV genes, was introduced for surveillance and characterization of RVs. This study characterized the common circulating strains in Vellore, India from 2002 to 2017 to understand rotavirus strain diversity and evolution using Whole genome sequencing (WGS) carried out on Illumina MiSeq. The 89% (92% of Wa-like, 86% of DS-1-like) of strains had classical constellations, while reassortant constellations were seen in 11% (8% of Wa-like, 14% of DS-1-like) of the strains. The rare E6-NSP4 in combination with DS-1 like G1P[8] and the emergence of the OP-354 subtype of P[8] were identified. Phylogenetics of RV strains revealed multiple subtypes circulating in the past 15 years, with strong evidence of animal to human gene transmission among several strains.

A shift in circulating rotaviral genotypes among hospitalized neonates

In neonates, rotavirus (RV) infection is generally nosocomial. The control of rotaviral infection within hospital settings is challenging due to prolonged shedding of the virus and contamination of the surrounding environment. There are few studies that have reported asymptomatic infection within neonates. In this study, neonates were screened for RV infection and possible clinical manifestations that may play a role in RV acquisition were analysed. Stool samples were collected from 523 hospitalized neonates admitted for > 48 h in a low-cost and higher-cost tertiary centre. RV antigen was screened using ELISA and the samples which tested positive were confirmed by semi-nested RT-PCR. RV was detected in 34% of participants and genotypes identified included G12P[11] (44.4%), G10 P[11] (42.6%), G10G12P[11] (10.1%) and G3P[8] (2.9%). ICU admissions were associated with higher viral shedding (p < 0.05). Hospitalization in the low-cost facility ICU was associated with higher RV acquisition risk (p < 0.05). RV was detected in higher rates (36.9%) among neonates with gastrointestinal manifestations. G10P[11] was the predominant genotype for several years (1988–2016) among neonates within India. The preponderance of an emerging G12P[11] genotype and heterotypic distribution was documented. RV surveillance is important to identify emerging strains and establish the road ahead in managing RV infection.

[Phylodynamic characteristics of the Russian population of rotavirus А (Reoviridae: Sedoreovirinae: Rotavirus) based on the VP6 gene]

INTRODUCTION

Rotavirus A is one of the leading causes of acute gastroenteritis in children in the first years of life. Rotavirus infection is currently classified as a preventable infection. The most abundant rotavirion protein is VP6.

MATERIAL AND METHODS

Phylogenetic analysis and calculation of phylodynamic characteristics were carried out for 262 nucleotide sequences of the VP6 gene of rotavirus species A, isolated in Russia, using the BEAST v.1.10.4 software package. The derivation and analysis of amino acid sequences was performed using the MEGAX program.

RESULTS

This study provides phylodynamic characteristics of the rotaviruses in Russia based on the sequences coding VP6 protein. Bayesian analysis showed the circulation of rotaviruses of three sublineages of genotype I1 and three sublineages of genotype I2 in Russia. The level of accumulation of mutations was established, which turned out to be similar for genotypes I1 and I2 and amounted to 7.732E-4 and 1.008E-3 nucleotides/site/year, respectively. The effective population sizes based on nucleotide sequences of the VP6 I1 and I2 genotypes are relatively stable while after the 2000s there is a tendency of its decreasing. Comparative analysis of the amino acid sequences in the region of the intracellular neutralization sites A (231-260 aa) and B (265-292 aa) made it possible to reveal a mutation in position V252I in a proportion of Russian strains of genotype I1 some strains of genotypes I1 and I2 had mutation I281V. These substitutions were not associated with any sublineages to which the strains belong. The analysis of three T-cell epitopes revealed four amino acid differences (in aa positions 305, 315, 342, 348) that were associated with the first or second genogroup.

CONCLUSION

Based on the phylodynamic characteristics and amino acid composition of antigenic determinants, it was concluded that the VP6 protein is highly stable and could potentially be a good model for development of a rotavirus vaccine.

Assessment of risk of intussusception after pilot rollout of rotavirus vaccine in the Indian public health system

BACKGROUND

Pre-licensure trials of ROTAVAC® were not adequately powered to assess risk of intussusception, a rare adverse event associated with other rotavirus vaccines in some settings. We examined the risk of intussusception after ROTAVAC® vaccination among Indian infants during pilot rollout of the vaccine in the public health system in three states - Himachal Pradesh, Maharashtra and Tamil Nadu.

METHODS

Passive surveillance for intussusception was set up in 35 sentinel health facilities covering 26.3 million population in the three states under monitoring of an Interministerial-Interagency Steering Committee. Clinical and immunization data were collected by independent teams. An expert committee blinded to vaccination status, classified intussusception cases using Brighton criteria. The self-controlled case-series method was used to estimate risk of intussusception (Brighton Level 1) after ROTAVAC® vaccination.

RESULTS

151 intussusception cases were included in the analysis. The relative incidence (incidence during the risk period compared to the control period) 1-21 days after doses 1 and 2 combined was 1.56 (95% CI, 0.0-5.28) and that for three doses combined was 1.88 (95% CI, 0.76-4.30). Attributable risk 1-21 days after doses 1 and 2 combined was 0.11 (95% CI, 0.0-0.25) and that for 3 doses combined was 0.42 (95% CI, 0.0-0.70) per 100,000 doses.

CONCLUSIONS

No increased risk of intussusception within 21 days of receipt of the first two doses combined or all 3 doses combined of ROTAVAC® was detected.

Gene-edited vero cells as rotavirus vaccine substrates

Background

Rotavirus (RV) is a leading cause of severe gastroenteritis globally and can cause substantial morbidity associated with gastroenteritis in children <5 years of age. Orally administered live-attenuated RV vaccines offer protection against disease but vaccination efforts have been hampered by high manufacturing costs and the need to maintain a cold chain.

Methods

A subset of Vero cell host genes was identified by siRNA that when knocked down increased RV replication and these anti-viral host genes were individually deleted using CRISPR-Cas9.

Results

Fully-sequenced gene knockout Vero cell substrates were assessed for increased RV replication and RV vaccine antigen expression compared to wild type Vero cells. The results showed that RV replication and antigen production were logs higher in Vero cells having an EMX2 gene deletion compared to other Vero cell substrates tested.

Conclusions

We used siRNAs to screen for host genes that negatively affected RV replication, then CRISPR-Cas9 gene editing to delete select genes. The gene editing led to the development of enhanced RV vaccine substrates supporting a potential path forward for improving RV vaccine production.

Therapeutics and Immunoprophylaxis Against Noroviruses and Rotaviruses: The Past, Present, and Future

Background:

Noroviruses and rotaviruses are important viral etiologies of severe gastroenteritis. Noroviruses are the primary cause of nonbacterial diarrheal outbreaks in humans, whilst rotaviruses are a major cause of childhood diarrhea. Although both enteric pathogens substantially impact human health and economies, there are no approved drugs against noroviruses and rotaviruses so far. On the other hand, whilst the currently licensed rotavirus vaccines have been successfully implemented in over 100 countries, the most advanced norovirus vaccine has recently completed phase-I and II trials.

Methods:

We performed a structured search of bibliographic databases for peer-reviewed research litera-ture on advances in the fields of norovirus and rotavirus therapeutics and immunoprophylaxis.

Results:

Technological advances coupled with a proper understanding of viral morphology and replication over the past decade has facilitated pioneering research on therapeutics and immunoprophylaxis against noroviruses and rotaviruses, with promising outcomes in human clinical trials of some of the drugs and vaccines. This review focuses on the various developments in the fields of norovirus and rotavirus thera-peutics and immunoprophylaxis, such as potential antiviral drug molecules, passive immunotherapies (oral human immunoglobulins, egg yolk and bovine colostral antibodies, llama-derived nanobodies, and anti-bodies expressed in probiotics, plants, rice grains and insect larvae), immune system modulators, probiot-ics, phytochemicals and other biological substances such as bovine milk proteins, therapeutic nanoparti-cles, hydrogels and viscogens, conventional viral vaccines (live and inactivated whole virus vaccines), and genetically engineered viral vaccines (reassortant viral particles, virus-like particles (VLPs) and other sub-unit recombinant vaccines including multi-valent viral vaccines, edible plant vaccines, and encapsulated viral particles).

Conclusions:

This review provides important insights into the various approaches to therapeutics and im-munoprophylaxis against noroviruses and rotaviruses..

The rotavirus vaccine development pipeline

Rotavirus disease is a leading global cause of mortality and morbidity in children under 5 years of age. The effectiveness of the two globally used oral rotavirus vaccines quickly became apparent when introduced into both developed and developing countries, with significant reductions in rotavirus-associated mortality and hospitalizations. However, the effectiveness and impact of the vaccines is reduced in developing country settings, where the burden and mortality is highest.

New rotavirus vaccines, including live oral rotavirus candidates and non-replicating approaches continue to be developed, with the major aim to improve the global supply of rotavirus vaccines and for local implementation, and to improve vaccine effectiveness in developing settings. This review provides an overview of the new rotavirus vaccines in development by developing country manufacturers and provides a rationale why newer candidates continue to be explored. It describes the new live oral rotavirus vaccine candidates as well as the non-replicating rotavirus vaccines that are furthest along in development.

Complete genotyping of unusual species A rotavirus G12P[11] and G10P[14] isolates and evidence of frequent in vivo reassortment among the rotaviruses detected in children with diarrhea in Kolkata, India, during 2014

Species A rotaviruses (RVA) are the most important cause of acute gastroenteritis in the young of humans and many animal species globally. G1P[8], G2P[4], G3P[8], G4P[8], G9P[6/8] and G12P[6/8] are the predominantly isolated genotypes throughout the world including India. Unusual genotypes from different host species such as G5, G6, G8, G10 and G11 have also been reported in humans with low frequency. In the present study, among >650 RVA positive stool samples collected from children with diarrhea in Kolkata, India, during 2014, two isolates each of the genotype G12P[11] and G10P[14] were obtained and their genomes completely sequenced. The full genotype constellations were G12-P[11]-I1-R1-C1-M2-A1-N1-T2-E1-H1 and G12-P[11]-I1-R1-C1-M1-A5-N1-T1-E1-H1 for G12P[11] viruses, suggesting several reassortments between Wa- and DS-1-like human RVA strains, including possible reassortment of a simian NSP1 gene. The G10P[14] viruses (G10-P[14]-I2-R2-C2-M2-A11-N2-T6-E2-H3) were found to contain multiple genes closely related to RVAs of artiodactyl origin, highlighting the role of inter-host species transmissions of RVAs. From the G/P constellation of all RVA isolates, it could be concluded that approximately one quarter had likely arisen from reassortment events in vivo among RVAs of 'usual' genotypes.

Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part I: Overview, vaccines for enteric viruses and Vibrio cholerae

Efforts to develop vaccines for prevention of acute diarrhea have been going on for more than 40 y with partial success. The myriad of pathogens, more than 20, that have been identified as a cause of acute diarrhea throughout the years pose a significant challenge for selecting and further developing the most relevant vaccine candidates. Based on pathogen distribution as identified in epidemiological studies performed mostly in low-resource countries, rotavirus, Cryptosporidium, Shigella, diarrheogenic E. coli and V. cholerae are predominant, and thus the main targets for vaccine development and implementation. Vaccination against norovirus is most relevant in middle/high-income countries and possibly in resource-deprived countries, pending a more precise characterization of disease impact. Only a few licensed vaccines are currently available, of which rotavirus vaccines have been the most outstanding in demonstrating a significant impact in a short time period. This is a comprehensive review, divided into 2 articles, of nearly 50 vaccine candidates against the most relevant viral and bacterial pathogens that cause acute gastroenteritis. In order to facilitate reading, sections for each pathogen are organized as follows: i) a discussion of the main epidemiological and pathogenic features; and ii) a discussion of vaccines based on their stage of development, moving from current licensed vaccines to vaccines in advanced stage of development (in phase IIb or III trials) to vaccines in early stages of clinical development (in phase I/II) or preclinical development in animal models. In this first article we discuss rotavirus, norovirus and Vibrio cholerae. In the following article we will discuss Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic), and Campylobacter jejuni.

Current status of rotavirus vaccines

BACKGROUND

Rotaviruses remain the major cause of childhood diarrheal disease worldwide and of diarrheal deaths of infants and children in developing countries. The huge burden of childhood rotavirus-related diarrhea in the world continues to drive the remarkable pace of vaccine development.

DATA SOURCES

Research articles were searched using terms "rotavirus" and "rotavirus vaccine" in MEDLINE and PubMed. Articles not published in the English language, articles without abstracts, and opinion articles were excluded from the review. After preliminary screening, all articles were reviewed and synthesized to provide an overview of current vaccines and vaccination programs.

RESULTS

In this review of the global rotavirus vaccines and vaccination programs, the principles of rotavirus vaccine development and the efficacy of the currently licensed vaccines from both developed and developing countries were summarized.

CONCLUSIONS

Rotavirus is a common cause of diarrhea in children in both developed and developing countries. Rotavirus vaccination is a cost-effective measure to prevent rotavirus diarrhea.

Multi-center surveillance of rotavirus diarrhea in hospitalized children <5 years of age in India, 2009-2012

Diarrheal disease due to Group A rotaviruses continues to be an important cause of morbidity in the developing world and India contributes significantly to the disease burden. Surveillance carried out between July 2009 and June 2012 at two medical centers in south India and one center in north India estimated 39% of all diarrheal admissions to be due to rotavirus. The most prevalent genotype isolated was G1P[8](33%) followed by G2P[4](17%). G9P[4] has also emerged as a significant cause of rotavirus diarrhea. No seasonal variation was noticed from the centers in south India, whereas we observed increased rotavirus diarrhea in the center in north India during March and April.

Absence of genetic differences among G10P[11] rotaviruses associated with asymptomatic and symptomatic neonatal infections in Vellore, India

Rotaviruses (RVs) are leading causes of severe diarrhea and vomiting in infants and young children. RVs with G10P[11] genotype specificity have been associated with symptomatic and asymptomatic neonatal infections in Vellore, India. To identify possible viral genetic determinants responsible for differences in symptomology, the genome sequences of G10P[11] RVs in stool samples of 19 neonates with symptomatic infections and 20 neonates with asymptomatic infections were determined by Sanger and next-generation sequencing. The data showed that all 39 viruses had identical genotype constellations (G10-P[11]-I2-R2-C2-M2-A1-N1-T1-E2-H3), the same as those of the previously characterized symptomatic N155 Vellore isolate. The data also showed that the RNA and deduced protein sequences of all the Vellore G10P[11] viruses were nearly identical; no nucleotide or amino acid differences were found that correlated with symptomatic versus asymptomatic infection. Next-generation sequencing data revealed that some stool samples, both from neonates with symptomatic infections and from neonates with asymptomatic infections, also contained one or more positive-strand RNA viruses (Aichi virus, astrovirus, or salivirus/klassevirus) suspected of being potential causes of pediatric gastroenteritis. However, none of the positive-strand RNA viruses could be causally associated with the development of symptoms. These results indicate that the diversity of clinical symptoms in Vellore neonates does not result from genetic differences among G10P[11] RVs; instead, other undefined factors appear to influence whether neonates develop gastrointestinal disease symptoms.

IMPORTANCE

Rotavirus (RV) strains have been identified that preferentially replicate in neonates, in some cases, without causing gastrointestinal disease. Surveillance studies have established that G10P[11] RVs are a major cause of neonatal infection in Vellore, India, with half of infected neonates exhibiting symptoms. We used Sanger and next-generation sequencing technologies to contrast G10P[11] RVs recovered from symptomatic and asymptomatic neonates. Remarkably, the data showed that the RNA genomes of the viruses were virtually indistinguishable and lacked any differences that could explain the diversity of clinical outcomes among infected Vellore neonates. The sequencing results also indicated that some symptomatic and some asymptomatic Vellore neonates were infected with other enteric viruses (Aichi virus, astrovirus, salvirus/klassevirus); however, none could be correlated with the presence of symptoms in neonates. Together, our findings suggest that other poorly defined factors, not connected to the genetic makeup of the Vellore G10P[11] viruses, influence whether neonates develop gastrointestinal disease symptoms.

Vaccine development and deployment: opportunities and challenges in India

The Indian economy is among the fastest growing economies in the world. The country forayed into manufacturing vaccines starting with a few public-sector manufacturers in the late 1960s but has emerged as the major supplier of basic Expanded Programme on Immunization vaccines to the United Nations Children's Fund (UNICEF) because of substantial private-sector investment in the area. The Indian vaccine industry is now able to produce new and more complex vaccines such as the meningitis, Haemophilus influenzae type b, and pneumococcal conjugate vaccines, rotavirus vaccine and influenza A (H1N1) vaccines. This has been possible because of an attractive investment environment, effective and innovative governmental support, international partnerships and the growing in-country technical work force. A large number of vaccines, including those mentioned, is available and administered in the private sector within the country, but India has been slow in introducing new vaccines in its publically funded programs. Growth in the economy and technological accomplishments are not reflected in a reduction in health inequalities, and India continues to contribute significantly to global child mortality figures. This paper reviews the development of the Indian vaccine industry, policy support for it and its current status. It also highlights opportunities and challenges for the introduction of new and underutilized vaccines at home.

Waterborne Viral Gastroenteritis: An Introduction to Common Agents

Acute gastroenteritis is among the most common illnesses of human beings, and its associated morbidity and mortality are greatest among those at the extremes of age; children and elderly. During the 1970s, several viruses were associated with this syndrome, which are now known to be caused mainly by viruses belonging to four distinct families—rotaviruses, caliciviruses, astroviruses, and adenoviruses. Other viruses, such as the toroviruses, picobirnaviruses, coronavirus, and enterovirus 22, may play a role as well. Transmission by food or water has been documented for astroviruses, caliciviruses, rotaviruses, and norovirus. In developing countries, gastroenteritis is a common cause of death in children <5 years, while deaths from diarrhea are less common, much illness leads to hospitalization or doctor visits. Laboratory confirmation of waterborne illness is based on demonstration of virus particles or antigen in stool, detection of viral nucleic acid in stool, or demonstration of a rise in specific antibody to the virus. Newer methods for syndrome surveillance of acute viral gastroenteritis are being developed like multiplex real-time reverse transcriptase PCRs. Application of these more sensitive methods to detect and characterize individual agents is just beginning, but has already opened up new avenues to reassess their disease burden, examine their molecular epidemiology, and consider new directions for their prevention and control through vaccination, improvements in water quality, and sanitary practices.

Waterborne human pathogenic viruses of public health concern

In recent years, the impending impact of waterborne pathogens on human health has become a growing concern. Drinking water and recreational exposure to polluted water have shown to be linked to viral infections, since viruses are shed in extremely high numbers in the faeces and vomit of infected individuals and are routinely introduced into the water environment. All of the identified pathogenic viruses that pose a significant public health threat in the water environment are transmitted via the faecal-oral route. This group, are collectively known as enteric viruses, and their possible health effects include gastroenteritis, paralysis, meningitis, hepatitis, respiratory illness and diarrhoea. This review addresses both past and recent investigations into viral contamination of surface waters, with emphasis on six types of potential waterborne human pathogenic viruses. In addition, the viral associated illnesses are outlined with reference to their pathogenesis and routes of transmission.

The status of live viral vaccination in early life

The need for neonatal vaccines is supported by the high disease burden during the first year of life particularly in the first month. Two-thirds of childhood deaths are attributable to infectious diseases of which viruses represent key pathogens. Many infectious diseases have the highest incidence, severity and mortality in the first months of life, and therefore early life vaccination would provide significant protection and life savings. For some childhood viral diseases successful vaccines exist, such as against measles, mumps, rubella, varicella, influenza poliovirus, and rotavirus, but their use in the first year particularly at birth is not yet practiced. Vaccines against other key pathogens continue to elude scientists such as against respiratory syncytial virus. The obstacles for early and neonatal vaccination are complex and include host factors, such as a developing immune system and the interference of passively acquired antibodies, as well vaccine-specific issues, such as optimal route of administration, titer and dosing requirements. Importantly, additional host and infrastructure barriers also present obstacles to neonatal vaccination in the developing world where morbidity and mortality rates are highest. This review will highlight the current live viral vaccines and their use in the first year of life, focusing on efficacy and entertaining the barriers that exist. It is important to understand the successes of current vaccines and use this knowledge to determine strategies that are successful in young infants and for the development of new vaccines for use in early life.

A systematic review of rotavirus strain diversity in India, Bangladesh, and Pakistan

Of the estimated half-million deaths from rotavirus globally each year, approximately one-third (N = 160,000 deaths) occur in the Indian subcontinent (defined as India, Bangladesh, and Pakistan). Two commercial vaccines are available for use and recommended by WHO, although the prohibitive vaccine price has limited their introduction into routine childhood immunization programs. New rotavirus vaccines are in late clinical development, including two advanced candidates in India. As significant shifts in rotavirus strain diversity have occurred in the past three decades and questions remain regarding whether strain replacement may occur following introduction of rotavirus vaccines, it is important to understand the temporal and regional strain diversity profile before vaccine introduction. We reviewed 33 peer-reviewed manuscripts from the Indian subcontinent and found that the most common G-types (G1-4) and P-types (P[4] and P[8]) globally accounted for three-fourths of all strains in the subcontinent. However, strains varied by region, and temporal analysis showed the decline of G3 and G4 in recent years and the emergence of G9 and G12. Our findings underscore the large diversity of rotavirus strains in the Indian subcontinent and highlight the need to conduct surveillance on a regional scale to better understand strain diversity before and after rotavirus vaccine introduction.

Remaining issues and challenges for rotavirus vaccine in preventing global childhood diarrheal morbidity and mortality

Rotavirus vaccines have had a dramatic impact on morbidity and mortality from diarrhea among children in high- and middle-income countries that have introduced the vaccine into their national immunization programs. Widespread introduction of rotavirus vaccine in developing countries is imminent and their full potential in reducing the global burden from severe childhood diarrhea may soon be realized. The objectives of this paper are to describe the remaining issues and challenges in ensuring the success of the global rotavirus vaccination program and to discuss further research needed to help address them.

Use of PCR-based assays for the detection of the adventitious agent porcine circovirus type 1 (PCV1) in vaccines, and for confirming the identity of cell substrates and viruses used in vaccine production

Safety and quality are important issues for vaccines. Whereas reversion to virulence poses a safety risk with live attenuated vaccines, the potential for the presence of adventitious agents is also an issue of vaccine quality. The recent detection or porcine circovirus type 1 (PCV1) in human vaccines has further highlighted the importance of quality control in vaccine production. The purpose of this study was to use a novel conventional PCR to detect PCV1, and subsequently screen materials used in the manufacture of vaccines at Bharat Biotech International Limited, India. The genome or gene fragments of PCV1 were not detected in any of the vaccines and materials tested, including the live attenuated rotavirus vaccine candidate ROTAVAC(®). Further, the identity of the cells and the viruses used as starting materials in the manufacture of these vaccines was confirmed by species-specific PCR or virus-specific RT-PCR, and no cross-contamination was detected in any case. The methods can be applied for regular in-house quality control screening of raw materials and seeds/banks, as well as formulated vaccines.

Prevention of rotavirus gastroenteritis in infants and children: rotavirus vaccine safety, efficacy, and potential impact of vaccines

Rotavirus infection is the most common cause of severe gastroenteritis globally, with greater than 86% of deaths occurring in low-income and middle-income countries. There are two rotavirus vaccines currently licensed in the United States and prequalified by the World Health Organization. RV1 is a monovalent attenuated human rotavirus strain, given orally in two doses. RV5 is a pentavalent human-bovine reassortant rotavirus vaccine, given orally in three doses. A third rotavirus vaccine, LLV, is a lamb rotavirus strain given orally as a single dose, which is currently available only in China. RV1 and RV5 have been shown to be highly efficacious in developed countries, and initial results from trials in Africa and Asia are promising as well. At least three other vaccines are in development, which are being developed by manufacturers of developing countries. Further studies are needed to clarify issues including administration of oral rotavirus vaccines with breastfeeding and other oral vaccines, and alterations in dosing schedule. Using new data on global diarrheal burden, rotavirus is estimated to cause 390,000 deaths in children younger than 5 years. Should rotavirus vaccines be introduced in the routine immunization programs of all countries, a potential of 170,000 deaths could be prevented annually. The largest impact on mortality would be seen in low-income and middle-income countries, despite poor immunization coverage and lower efficacy. Therefore, international efforts are needed to ensure that rotavirus vaccines reach the populations with highest burden of rotavirus disease.

Complete genome sequence analysis of candidate human rotavirus vaccine strains RV3 and 116E

Rotaviruses (RVs) cause severe gastroenteritis in infants and young children; yet, several strains have been isolated from newborns showing no signs of clinical illness. Two of these neonatal strains, RV3 (G3P[6]) and 116E (G9P[11]), are currently being developed as live-attenuated vaccines. In this study, we sequenced the eleven-segmented double-stranded RNA genomes of cell culture-adapted RV3 and 116E and compared their genes and protein products to those of other RVs. Using amino acid alignments and structural predictions, we identified residues of RV3 or 116E that may contribute to attenuation or influence vaccine efficacy. We also discovered residues of the VP4 attachment protein that correlate with the capacity of some P[6] strains, including RV3, to infect newborns versus older infants. The results of this study enhance our understanding of the molecular determinants of RV3 and 116E attenuation and are expected to aid in the ongoing development of these vaccine candidates.

Rotavirus infection in the neonatal nurseries of a tertiary care hospital in India

BACKGROUND

The majority of neonatal rotavirus infections are believed to be asymptomatic, and protection from subsequent infection and disease has been reported in neonatally infected children. In this study, we present the results of a 4-year prospective surveillance in the neonatal nurseries of a tertiary care hospital in south India.

METHODS

Stool samples from neonates admitted for >48 hours either with gastrointestinal (GI) symptoms or with nonenteric pathology were screened for rotavirus. Careful assessment of clinical data was carried out. G- and P-typing for all symptomatic rotavirus positive cases and equal number of asymptomatic controls from the same month was determined by reverse transcription polymerase chain reaction.

RESULTS

Rotavirus was detected in 43.9% of 1411 neonates, including those with and without gastrointestinal disease. Rotavirus detection was significantly higher among neonates with GI disease (55.5%) than asymptomatic neonates (44.4%) (P < 0.001). Rotavirus was seen in association with diarrhea, vomiting, feed intolerance, necrotizing enterocolitis, hematochezia, gastroesophageal reflux, and abdominal distension. Diarrhea was significantly more frequent in neonates with rotavirus infection (P < 0.001) whereas uninfected neonates developed significantly more feeding intolerance (P < 0.001). Significantly greater proportion of term neonates with GI disease were positive for rotavirus than preterm neonates (P < 0.001). G10P[11] was the most common genotype associated with both symptomatic and asymptomatic infections.

CONCLUSIONS

This study documents the high rates of rotavirus infection in the neonatal nurseries and the continuing detection of the G10P[11] strain associated with GI disease in Vellore.

Parenteral administration of RF 8-2/6/7 rotavirus-like particles in a one-dose regimen induce protective immunity in mice

Rotavirus virus-like particles (RV-VLPs) represent a novel strategy for development of a rotavirus subunit vaccine. In this study, RF 8-2/6/7-VLPs with rotavirus VP8 protein (amino acid 1-241 of VP4) fused to the amino terminal end of a truncated VP2, were evaluated for their immunogenic and protective properties. A single intramuscular dose of, either 2 or 20 microg, RF 8-2/6/7-VLPs alone or combined with a potent adjuvant poly[di(carboxylatophenoxy)]phosphazene] (PCPP) induced rotavirus-specific serum IgG and IgA, fecal IgG titers that were enhanced 5-90-fold by adjuvant. Passive protective immunity was achieved in offspring to dams vaccinated with 2 and 20 microg RV-VLPs in presence of adjuvant and 20 microg RV-VLP without adjuvant.

Emergence of G12 rotavirus strains in Delhi, India, in 2000 to 2007

The prospect that rotavirus diarrhea in children may soon be prevented by vaccines has placed a new priority on understanding the diversity of rotavirus strains and the mechanism by which these strains evolve over time. We have characterized a total of 465 rotavirus strains collected in North India from 2000 to 2007 for G and P types by reverse transcription-PCR and sequencing. The novel G12 rotavirus strains recently detected in other countries were first detected in India in 2001 and have emerged as the predominant strains in Delhi, India, during 2005 to 2007. While the VP7 sequence was highly homologous among G12 strains isolated in Delhi, suggesting recent emergence from a common ancestor, the strains had a diverse constellation of other gene segments, demonstrating substantial reassortment. For the entire period, the common rotavirus G types G1 (26%), G2 (25%), and G9 (14%) comprised 65% of the strains, and common P types, P[4] (19%), P[6] (22%), and P[8] (35%), comprised 76% of the total P types. Of note, we detected a high percentage of unusual (17%) strains and fecal specimens with mixed (12% G and 15% P) rotavirus infections having a variety of genomic constellations. For the first time, we identified two novel rotavirus strains with unusual G/P combinations, G2P[11] and G3P[11], in patients with diarrhea. The study highlights the great diversity among rotaviruses isolated from Indian children, the opportunity for genetic reassortment between strains, and the emergence of a novel G12 strain in our country. Due to the demonstrated effect of antigenic diversity on rotavirus vaccines, it will be important to continue careful monitoring of these strains as rotavirus vaccine programs are implemented in India.

Rotavirus vaccines: an overview

Rotavirus infection is the most common cause of severe diarrhea disease in infants and young children worldwide and continues to have a major global impact on childhood morbidity and mortality. Vaccination is the only control measure likely to have a significant impact on the incidence of severe dehydrating rotavirus disease. In 1999, a highly efficacious rotavirus vaccine licensed in the United States, RotaShield, was withdrawn from the market after 14 months because of its association with intussusception. Two new live, oral, attenuated rotavirus vaccines were licensed in 2006: the pentavalent bovine-human reassortant vaccine (RotaTeq) and the monovalent human rotavirus vaccine (Rotarix). Both vaccines have demonstrated very good safety and efficacy profiles in large clinical trials in western industrialized countries and in Latin America. Careful surveillance has not revealed any increased risk of intussusception in the vaccinated groups with either vaccine. The new rotavirus vaccines are now introduced for routine use in a number of industrialized and developing countries. These new safe and effective rotavirus vaccines offer the best hope of reducing the toll of acute rotavirus gastroenteritis in both developed and developing countries.

First detection of G12 rotaviruses in newborns with neonatal rotavirus infection at all India Institute of Medical Sciences, New Delhi, India

Rotavirus genotype G12 strains were detected for the first time among newborns with asymptomatic rotavirus infection (74% of 39 rotavirus strains isolated from the infected infants were genotype G12) in the nursery of the All India Institute of Medical Sciences during a period from 2005 to 2006. Sequence analysis of the VP7 genes from these neonatal strains indicated a high level of homology to other G12 strains reported worldwide, suggesting the recent emergence of these strains in humans. Such nosocomial infections of newborns represent a potential source of introduction of novel rotavirus serotypes into the community.

Rotavirus vaccines--an update

Rotavirus infection is the most common cause of severe diarrhea disease in infants and young children worldwide and continues to have a major global impact on childhood morbidity and mortality. Vaccination is the only control measure likely to have a significant impact on the incidence of severe dehydrating rotavirus disease. Rotavirus disease prevention efforts suffered a severe setback in 1999 with the withdrawal of the RRV-TV vaccine less than a year after its introduction. Several new rotavirus vaccines have been developed and have proven to be safe and efficacious. These new safe and effective rotavirus vaccines offer the best hope of reducing the toll of acute rotavirus gastroenteritis in both developed and developing countries.

Neonatal infection with G10P[11] rotavirus did not confer protection against subsequent rotavirus infection in a community cohort in Vellore, South India

BACKGROUND

Various observational studies have suggested that neonatal rotavirus infection confers protection against diarrhea due to subsequent rotavirus infection. We examined the incidence of rotavirus infection and diarrhea during the first 2 years of life among children infected with the G10P[11] rotavirus strain during the neonatal period and those not infected with rotavirus.

METHODS

Children were recruited at birth and were followed up at least twice weekly. Stool samples, collected every 2 weeks for surveillance and at each episode of diarrhea, were screened by enzyme-linked immunosorbent assay and were genotyped by polymerase chain reaction.

RESULTS

Among 33 children infected neonatally with G10P[11] and 300 children not infected with rotavirus, there was no significant difference in the rates of rotavirus-positive diarrhea (rate ratio [RR], 1.05 [95% confidence interval [CI], 0.61-1.79]), moderate or severe rotavirus-positive diarrhea (RR, 1.42 [95% CI, 0.73-2.78]), or asymptomatic rotavirus shedding (RR, 1.25 [95% CI, 0.85-1.83]).

CONCLUSION

Neonatal G10P[11] infection with a strain resembling a vaccine candidate did not confer protection against subsequent rotavirus infection or diarrhea of any severity in this setting.

Rotavirus vaccines: current prospects and future challenges

Rotavirus is the most common cause of severe diarrhoea in children worldwide and diarrhoeal deaths in children in developing countries. Accelerated development and introduction of rotavirus vaccines into global immunisation programmes has been a high priority for many international agencies, including WHO and the Global Alliance for Vaccines and Immunizations. Vaccines have been developed that could prevent the enormous morbidity and mortality from rotavirus and their effect should be measurable within 2-3 years. Two live oral rotavirus vaccines have been licensed in many countries; one is derived from an attenuated human strain of rotavirus and the other combines five bovine-human reassortant strains. Each vaccine has proven highly effective in preventing severe rotavirus diarrhoea in children and safe from the possible complication of intussusception. In developed countries, these vaccines could substantially reduce the number and associated costs of child hospitalisations and clinical visits for acute diarrhoea. In developing countries, they could reduce deaths from diarrhoea and improve child survival through programmes for childhood immunisations and diarrhoeal disease control. Although many scientific, programmatic, and financial challenges face the global use of rotavirus vaccines, these vaccines-and new candidates in the pipeline-hold promise to make an immediate and measurable effect to improve child health and survival from this common burden affecting all children.

Safety and immunogenicity of two live attenuated human rotavirus vaccine candidates, 116E and I321, in infants: results of a randomised controlled trial

We evaluated safety and immunogenicity of two orally administered human rotavirus vaccine candidates 116E and I321. Ninety healthy infants aged 8 weeks received a single dose of 116E (10(5)FFu (florescence focus units)), I321 (10(5)FFu) or placebo. There were no significant differences in the number of adverse events. Fever was reported by 6/30, 1/30 and 5/30 in the 116E, I321 and placebo groups; the corresponding figures for diarrhoea were 5/30, 8/29 and 3/30. Serum IgA seroconversion rates were 73%, 39% and 20% in the 116E, I321 and placebo groups, respectively. Vaccine virus was shed on days 3, 7 or 28 in 11/30 infants of the 116E and none in the other two groups. The 116E strain is attenuated, clinically safe and highly immunogenic with a single dose.

Rotavirus Vaccines: Targeting the Developing World

For the past 2 decades, rotavirus infection, the most common cause of severe diarrhea in children, has been a priority target for vaccine development. This decision to develop rotavirus vaccines is predicated on the great burden associated with fatal rotavirus disease (i.e., 440,000 deaths/year), the firm scientific basis for developing live oral vaccines, the belief that increased investment in development at this time could speed the introduction of vaccines in developing countries, and the appreciation that implementation of a vaccine program should result in a measurable decrease in the number of hospitalizations and deaths associated with rotavirus disease within 2-3 years. RotaShield (Wyeth-Ayerst), the first rotavirus vaccine licensed in the United States, was withdrawn after 9 months because of a rare association of the vaccine with the development of intussusception. In the developing world, this vaccine could still have had a measurable effect, because the benefits of preventing deaths due to rotavirus disease would have been substantially greater than the rare risk of intussusception. Two live oral vaccines being prepared by GlaxoSmithKline and Merck have completed large-scale clinical trials. The GlaxoSmithKline vaccine has been licensed in Mexico and the Dominican Republic, and the Merck vaccine could be licensed in the United States within 1 year; several other candidate vaccines are in earlier stages of testing. However, many challenges remain before any of these vaccines can be incorporated into childhood immunization programs in the developing world. First, vaccine efficacy, which has already been demonstrated in children in industrialized and middle-income countries, needs to be proven in poor developing countries in Africa and Asia. The safety of vaccines with regard to the associated risk of intussusception must be demonstrated as well. Novel financing strategies will be needed to ensure that new vaccines are affordable and available in the developing world. Decision makers and parents in developing countries need to know about this disease that has little name recognition and is rarely diagnosed. Finally, for the global effort toward the prevention of rotavirus disease to be successful, special efforts will be required in India, China, and Indonesia, because one-third of all deaths due to rotavirus disease occur in these countries, and because these countries depend almost entirely on vaccines manufactured domestically.