The Impact of Rotavirus Vaccines on Genotype Diversity: A Comprehensive Analysis of 2 Decades of Australian Surveillance Data.

Background: Introduction of rotavirus vaccines into national immunization programs (NIPs) could result in strain selection due to vaccine-induced selective pressure. This study describes the distribution and diversity of rotavirus genotypes before and after rotavirus vaccine introduction into the Australian NIP. State-based vaccine selection facilitated a unique comparison of diversity in RotaTeq and Rotarix vaccine states. Methods: From 1995 to 2015, the Australian Rotavirus Surveillance Program conducted genotypic analysis on 13051 rotavirus-positive samples from children <5 years of age, hospitalized with acute gastroenteritis. Rotavirus G and P genotypes were determined using serological and heminested multiplex reverse-transcription polymerase chain reaction assays. Results: G1P[8] was the dominant genotype nationally in the prevaccine era (1995-2006). Following vaccine introduction (2007-2015), greater genotype diversity was observed with fluctuating genotype dominance. Genotype distribution varied based on the vaccine implemented, with G12P[8] dominant in states using RotaTeq, and equine-like G3P[8] and G2P[4] dominant in states and territories using Rotarix. Conclusions: The increased diversity and differences in genotype dominance observed in states using RotaTeq (G12P[8]), and in states and territories using Rotarix (equine-like G3P[8] and G2P[4]), suggest that these vaccines exert different immunological pressures that influence the diversity of rotavirus strains circulating in Australia.

Human Neonatal Rotavirus Vaccine (RV3-BB) to Target Rotavirus from Birth.

BACKGROUND: A strategy of administering a neonatal rotavirus vaccine at birth to target early prevention of rotavirus gastroenteritis may address some of the barriers to global implementation of a rotavirus vaccine. METHODS: We conducted a randomized, double-blind, placebo-controlled trial in Indonesia to evaluate the efficacy of an oral human neonatal rotavirus vaccine (RV3-BB) in preventing rotavirus gastroenteritis. Healthy newborns received three doses of RV3-BB, administered according to a neonatal schedule (0 to 5 days, 8 weeks, and 14 weeks of age) or an infant schedule (8 weeks, 14 weeks, and 18 weeks of age), or placebo. The primary analysis was conducted in the per-protocol population, which included only participants who received all four doses of vaccine or placebo within the visit windows, with secondary analyses performed in the intention-to-treat population, which included all participants who underwent randomization. RESULTS: Among the 1513 participants in the per-protocol population, severe rotavirus gastroenteritis occurred up to the age of 18 months in 5.6% of the participants in the placebo group (28 of 504 babies), in 1.4% in the neonatal-schedule vaccine group (7 of 498), and in 2.7% in the infant-schedule vaccine group (14 of 511). This resulted in a vaccine efficacy of 75% (95% confidence interval [CI], 44 to 91) in the neonatal-schedule group (P<0.001), 51% (95% CI, 7 to 76) in the infant-schedule group (P=0.03), and 63% (95% CI, 34 to 80) in the neonatal-schedule and infant-schedule groups combined (combined vaccine group) (P<0.001). Similar results were observed in the intention-to-treat analysis (1649 participants); the vaccine efficacy was 68% (95% CI, 35 to 86) in the neonatal-schedule group (P=0.001), 52% (95% CI, 11 to 76) in the infant-schedule group (P=0.02), and 60% (95% CI, 31 to 76) in the combined vaccine group (P<0.001). Vaccine response, as evidenced by serum immune response or shedding of RV3-BB in the stool, occurred in 78 of 83 participants (94%) in the neonatal-schedule group and in 83 of 84 participants (99%) in the infant-schedule group. The incidence of adverse events was similar across the groups. No episodes of intussusception occurred within the 21-day risk period after administration of any dose of vaccine or placebo, and one episode of intussusception occurred 114 days after the third dose of vaccine in the infant-schedule group. CONCLUSIONS: RV3-BB was efficacious in preventing severe rotavirus gastroenteritis when administered according to a neonatal or an infant schedule in Indonesia. (Funded by the Bill and Melinda Gates Foundation and others; Australian New Zealand Clinical Trials Registry number, ACTRN12612001282875 .).

Safety and immunogenicity of RV3-BB human neonatal rotavirus vaccine administered at birth or in infancy: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Despite the success of rotavirus vaccines, suboptimal vaccine efficacy in regions with a high burden of disease continues to present a challenge to worldwide implementation. A birth dose strategy with a vaccine developed from an asymptomatic neonatal rotavirus strain has the potential to address this challenge and provide protection from severe rotavirus disease from birth. METHODS: This phase 2a randomised, double-blind, three-arm, placebo-controlled safety and immunogenicity trial was undertaken at a single centre in New Zealand between Jan 13, 2012, and April 17, 2014. Healthy, full-term (≥36 weeks gestation) babies, who weighed at least 2500 g, and were 0-5 days old at the time of randomisation were randomly assigned (1:1:1; computer-generated; telephone central allocation) according to a concealed block randomisation schedule to oral RV3-BB vaccine with the first dose given at 0-5 days after birth (neonatal schedule), to vaccine with the first dose given at about 8 weeks after birth (infant schedule), or to placebo. The primary endpoint was cumulative vaccine take (serum immune response or stool shedding of vaccine virus after any dose) after three doses. The immunogenicity analysis included all randomised participants with available outcome data. This trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611001212943. FINDINGS: 95 eligible participants were randomised, of whom 89 were included in the primary analysis. A cumulative vaccine take was detected in 27 (90%) of 30 participants in the neonatal schedule group after three doses of RV3-BB vaccine compared with four (13%) of 32 participants in the placebo group (difference in proportions 0·78, 95% CI 0·55-0·88; p<0·0001). 25 (93%) of 27 participants in the infant schedule group had a cumulative vaccine take after three doses compared with eight (25%) of 32 participants in the placebo group (difference in proportions 0·68, 0·44-0·81; p<0·0001). A serum IgA response was detected in 19 (63%) of 30 participants and 20 (74%) of 27 participants, and stool shedding of RV3-BB was detected in 21 (70%) of 30 participants and 21 (78%) of 27 participants in the neonatal and infant schedule groups, respectively. The frequency of solicited and unsolicited adverse events was similar across the treatment groups. RV3-BB vaccine was not associated with an increased frequency of fever or gastrointestinal symptoms compared with placebo. INTERPRETATION: RV3-BB vaccine was immunogenic and well tolerated when given as a three-dose neonatal or infant schedule. A birth dose strategy of RV3-BB vaccine has the potential to improve the effectiveness and implementation of rotavirus vaccines. FUNDING: Australian National Health and Medical Research Council, the New Zealand Health Research Council, and the Murdoch Childrens Research Institute.

Australian Rotavirus Surveillance Program annual report, 2012.

This report from the Australian Rotavirus Surveillance Program, together with collaborating laboratories Australia-wide, describes the rotavirus genotypes responsible for the hospitalisation of children with acute gastroenteritis during the period 1 January to 31 December 2012. During the survey period, 1,300 faecal samples were referred to the centre for rotavirus G and P genotype analysis, and of these 748 were confirmed as rotavirus positive. A total of 491 specimens were collected from children under 5 years of age, while 257 were from older children and adults. Genotype analysis revealed that G1P[8] was the dominant type in this reporting period, identified in 35% of strains nationally. Genotype G2P[4] was the second most common strain nationally, representing 28% of samples, followed by genotype G12P[8] (23%). This represents the first report where G12P[8] strains are a major cause of disease in this community. Fluctuations in genotype distribution were also observed based on the vaccine type in use. Genotype G2P[4] was more common in states and territories using Rotarix while G1P[8] was more common in states using RotaTeq. This survey of rotavirus strains circulating in 2012 highlights the continued fluctuations in rotavirus genotypes, with an annual change in dominant genotypes as well as emergence of a previously rare genotype, suggesting a dynamic wild-type population.

Bacteriophages in gut samples from pediatric Crohn's disease patients: metagenomic analysis using 454 pyrosequencing.

BACKGROUND: The role of bacteriophage in Crohn's disease (CD) is unknown. This study investigated the abundance of phages in ileal and colonic samples from pediatric CD patients and controls. METHODS: Ileal and colonic biopsies from 6 CD patients, gut wash samples from 3 CD patients, and ileal biopsies from 6 noninflammatory bowel disease patients (controls) were analyzed for the presence of bacteriophage using 454 high-throughput pyrosequencing. A sequence-independent single-primer amplification method was used to amplify viral sequences. RESULTS: A total of 186,143 high quality reads were obtained from the 4 sample populations. Contigs and sequence clusters (generated from unassembled singletons) were aligned with sequences from the National Center for Biotechnology Information viral reference database and analyzed by MEGAN. The largest number of viral hits was obtained from the CD gut wash samples (n = 691), followed by CD ileal samples (n = 52), control ileum samples (n = 20), and CD colonic samples (n = 1). The most abundant virus sequences identified belonged to the Caudovirales phage. CONCLUSIONS: Our study characterized a diverse phage community in the gut of CD patients. In this study, we have identified differences in phage composition between CD patients and control individuals. The large abundance of phages in CD ileum tissue and CD gut wash sample suggests a role of phage in CD development. The role of phage dysbiosis in CD is currently unknown but opens up a new area of research.

Identification of strains of RotaTeq rotavirus vaccine in infants with gastroenteritis following routine vaccination.

BACKGROUND: RotaTeq vaccine was introduced into the Australian National Immunisation Program in 2007. This study identified and characterised rotavirus strains excreted by infants who presented with symptoms of gastroenteritis following recent RotaTeq vaccination. METHODS: Fecal samples (N = 61) from children who developed gastroenteritis following recent RotaTeq vaccination were forwarded to the Australian Rotavirus Surveillance Program (ARSP). RotaTeq-positive samples were genotyped and regions of the VP3, VP4, VP6, and VP7 genes were sequenced. Also, 460 rotavirus-positive ARSP routine surveillance samples were analyzed by dot-blot Northern hybridization to detect RotaTeq vaccine-derived strains circulating in the community. RESULTS: Thirteen of the 61 samples collected from infants developing gastroenteritis after RotaTeq vaccination contained vaccine-derived (vd) rotavirus strains. Of these, 4 contained a vdG1P[8] strain derived by reassortment between the G1P[5] and G6P[8] parental vaccine strains. Northern hybridization analysis of 460 surveillance samples identified 3 samples that contained RotaTeq vaccine-derived strains, including 2 vdG1P[8] reassortant vaccine strains. CONCLUSIONS: During replication and excretion of RotaTeq vaccine, reassortment of parental strains can occur. Shedding of RotaTeq vaccine strains in 7 of 13 infants was associated with underlying medical conditions that may have altered their immune function. The benefits of vaccination outweigh any small risk of vaccine-associated gastroenteritis.

Expression profile of genes involved in pathogenesis of pediatric Crohn's disease.

BACKGROUND AND AIM: Expression profiling of genes specific to pediatric Crohn's Disease (CD) patients was performed to elucidate the molecular mechanisms underlying disease cause and pathogenesis at disease onset. METHODS: We used suppressive subtractive hybridization (SSH) and differential screening analysis to profile the mRNA expression patterns of children with CD and age- and sex-matched controls without inflammatory bowel disease (IBD). RESULTS: Sequence analysis of 1000 clones enriched by SSH identified 75 functionally annotated human genes, represented by 430 clones. The 75 genes have potential involvement in gene networks, such as antigen presentation, inflammation, infection mechanism, connective tissue development, cell cycle and cancer. Twenty-eight genes were previously described in association with CD, while 47 were new genes not previously reported in the context of IBD. Additionally, 29 of the 75 genes have been previously implicated in bacterial and viral infections. Quantitative real-time reverse transcription polymerase chain reaction performed on ileal-derived RNA from 13 CD and nine non-IBD patients confirmed the upregulation of extracellular matrix gene MMP2 (P = 0.001), and cell proliferation gene REG1A (P = 0.063) in our pediatric CD cohort. CONCLUSION: The retrieval of 28 genes previously reported in association with adult CD emphasizes the importance of these genes in the pediatric setting. The observed upregulation of REG1A and MMP2, and their known impact on cell proliferation and extracellular matrix remodeling, agrees with the clinical behavior of the disease. Moreover, the expressions of bacterial- and virus-related genes in our CD-patient tissues support the concept that microbial agents are important in the etiopathogenesis of CD.

Australian Rotavirus Surveillance Program annual report, 2010/11.

The Australian Rotavirus Surveillance Program together with collaborating laboratories Australia-wide conducts a laboratory based rotavirus surveillance program. This report describes the genotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during 1 July 2010 to 30 June 2011. This report represents the fourth year of surveillance following introduction of rotavirus vaccines into the National Immunisation Program. One thousand one hundred and twenty-seven faecal samples were referred to the centre for G and P genotype analysis using hemi-nested multiplex reverse transcription-polymerase chain reaction. Eight hundred and sixteen samples were confirmed as rotavirus positive. Of these, 551 were collected from children under 5 years of age, while 265 were from older children and adults. Genotype analysis revealed that a change in the dominant type occurred in this reporting period, such that genotype G2P[4] was the dominant type nationally, representing 51% of samples, followed by genotype G1P[8] (26.1%). Genotypes G3P[8] represented 11% of samples while G4P[8] re-emerged as an important genotype, and was identified in 6% of samples. Uncommon rotavirus G and P combinations continue to be identified, with G2P[8] and G9P[4] identified during this survey. Differences in genotype distribution based on vaccine usage continue to be evident in Australian states. This survey continues to highlight the fluctuations in rotavirus genotypes, with an annual change in dominant genotypes suggesting a more dynamic wild-type population.

Distribution of rotavirus genotypes after introduction of rotavirus vaccines, Rotarix® and RotaTeq®, into the National Immunization Program of Australia.

BACKGROUND: Rotavirus vaccines, RotaTeq and Rotarix, were introduced into the Australian National Immunization Program on July 1, 2007. The simultaneous introduction in different Australian states and territories provides a unique opportunity to compare the affect of each vaccine on the types of circulating rotavirus strains. This report describes the rotavirus genotypes responsible for the hospitalization of children during the first 2-year period after vaccine introduction. METHODS: A total of 764 rotavirus-associated diarrheal cases were collected from children presenting to hospital in 10 Australian centers. Rotavirus genotype was determined using reverse transcription polymerase chain reaction assays. RESULTS: G1P[8] was the dominant genotype nationally (52%), followed by G2P[4] (19.8%), G9P[8] (12.2%), and G3P[8] (11%). Differences in the prevalence rates of G2P[4] and G3P[8] were seen in the various states. G2P[4] strains were more prevalent in states using Rotarix, whereas G3P[8] strains were more prevalent in states using RotaTeq. CONCLUSIONS: Differences in rotavirus genotypes were observed across Australia, which suggest that different immune pressures are exerted by the different vaccines, but do not necessarily imply lack of protection by either vaccine. These differences may simply be related to the variation that can occur because of natural annual fluctuation in rotavirus strain prevalence.

Interaction of Crohn's disease susceptibility genes in an Australian paediatric cohort.

Genetic susceptibility is an important contributor to the pathogenesis of Crohn's disease (CD). We investigated multiple CD susceptibility genes in an Australian paediatric onset CD cohort. Newly diagnosed paediatric onset CD patients (n = 72) and controls (n = 98) were genotyped for 34 single nucleotide polymorphisms (SNPs) in 18 genetic loci. Gene-gene interaction analysis, gene-disease phenotype analysis and genetic risk profiling were performed for all SNPs and all genes. Of the 34 SNPs analysed, four polymorphisms on three genes (NOD2, IL23R, and region 3p21) were significantly associated with CD status (p<0.05). All three CD specific paediatric polymorphisms on PSMG1 and TNFRSF6B showed a trend of association with p<0.1. An additive gene-gene interaction involving TLR4, PSMG1, TNFRSF6B and IRGM was identified with CD. Genes involved in microbial processing (TLR4, PSMG1, NOD2) were significantly associated either at the individual level or in gene-gene interactive roles. Colonic disease was significantly associated with disease SNP rs7517847 (IL23R) (p<0.05) and colonic and ileal/colonic disease was significantly associated with disease SNP rs125221868 (IBD5) and SLC22A4 & SLC22A4/5 variants (p<0.05). We were able to demonstrate genetic association of several genes to CD in a paediatric onset cohort. Several of the observed associations have not been reported previously in association with paediatric CD patients. Our findings demonstrate that CD genetic susceptibility in paediatric patients presents as a complex interaction between numerous genes.

Australian Rotavirus Surveillance Program: annual report, 2009/2010.

The Australian Rotavirus Surveillance Program together with 15 collaborating laboratories Australia-wide conducts a laboratory based rotavirus surveillance program. This report describes the genotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2009 to 30 June 2010, the 3rd year of surveillance following introduction of rotavirus vaccines into the National Immunisation Program. Seven hundred and seventy-eight faecal samples were referred to the centre for G and P genotype analysis using hemi-nested multiplex reverse transcription-polymerase chain reaction. Of the 422 confirmed as rotavirus positive, genotype G1P[8] was the dominant type nationally, representing 49.3%, followed by genotype G2P[4] (21.1%). Genotypes G3P[8], G4P[8] and G9P[8] each represented less than 3% of circulating strains nationally. The dominance of G1P[8] was in part associated with a large outbreak of severe gastroenteritis in the Northern Territory in 2010. The identification of uncommon rotavirus genotype combinations has increased since vaccine introduction, with G1P[4], G2P[8] and G9P[4] identified during this survey. Single strains of G1P[6] and G4P[6] were identified during this study period. This survey continues to highlight the fluctuations in rotavirus genotypes, and results from this survey suggest there is limited genotype selection based on vaccine usage. However, the large G1P[8] outbreak of gastroenteritis in the Northern Territory may have resulted from vaccine pressure on wild-type strains.

Rotavirus strain surveillance--an Australian perspective of strains causing disease in hospitalised children from 1997 to 2007.

This study documents rotavirus strains causing severe disease in Australian children during the pre-vaccine era. During the period 1997-2007, rotavirus strains from national multi-centre hospital-based surveillance in Australia were analysed for G and P types. G1P[8] was the dominant genotype identified during the 11-year study, with intermittent peaks associated with genotypes G2P[4], G3P[8] and G9P[8]. The results provide baseline information of the G and P genotypes causing disease in Australian children, and highlight the unpredictable changes in genotype incidence that can occur on both a local and national level. To be optimally effective, rotavirus vaccines must prevent disease caused by all common rotavirus genotypes.

Mycobacterium avium subspecies paratuberculosis in children with early-onset Crohn's disease.

BACKGROUND: Mycobacterium avium subspecies paratuberculosis (MAP) is the most enduring infectious candidate that may be associated with inflammatory bowel disease (IBD). It is possible that the inconsistencies in the prevalence studies of MAP in adults reflect clinical differences in adult patients studied, including duration of disease and treatment regimens, and also in lack of specificity of some of the assays used. The aim was to determine the presence of MAP in children with symptoms of Crohn's disease (CD) and ulcerative colitis (UC), using gut biopsy tissue and peripheral blood mononuclear cells (PBMC) collected at initial endoscopic examination prior to clinical treatment. METHODS: Mucosal biopsies and/or PBMC specimens were collected from a total of 142 children, comprising 62 with CD, 26 with UC, and 54 with non-IBD. MAP-specific IS900 polymerase chain reaction (PCR) analysis was performed on all biopsies and PBMC specimens. Conventional MAP culture technique was performed on a subset of 10 CD, 2 UC, and 4 non-IBD patients to isolate MAP. RESULTS: MAP was identified by IS900 PCR significantly more often in mucosal biopsies from CD 39% (22/56) than from non-IBD 15% (6/39) patients (P < 0.05), and in PBMC from CD 16% (8/50) than from non-IBD 0% (0/31) patients (P < 0.05). Viable MAP were cultured from mucosal biopsies from 4/10 CD, 0/2 UC, and 0/4 non-IBD patients, but were not cultured from PBMC specimens. CONCLUSIONS: This unique study on the occurrence of MAP in gut tissue and blood from pediatric IBD patients suggests the possible involvement of MAP in the early stages of development of CD in children.

Australian Rotavirus Surveillance Program annual report, 2008/2009.

The Australian Rotavirus Surveillance Program together with collaborating laboratories Australia-wide, conducts a laboratory based rotavirus surveillance program. This report describes the genotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2008 to 30 June 2009, the second year of surveillance following introduction of rotavirus vaccine into the National Immunisation Program. Five hundred and ninety-two faecal samples from across Australia were examined for G and P genotype using hemi-nested multiplex reverse transcription-polymerase chain reaction assays. Of the 445 confirmed as rotavirus positive, genotype G2P[4] was the dominant type nationally, representing 50.3%, followed by genotype G1P[8] (22.5%). Genotypes G3P[8], G4P[8] and G9P[8] each represented less than 5% of circulating strains nationally. Uncommon rotavirus genotype combinations, including G1P[4] (n = 6), G4P[4] (n = 2) and single strains of G1P[6] and G3P[6] were identified during this study period. The national dominance of G2P[4] was associated with a large outbreak of severe gastroenteritis in Alice Springs in early 2009. This is the first report to describe G2P[4] as the dominant genotype nationally. Whether vaccine pressure has resulted in emergence of this genotype is not yet known.

Identification and characterisation of Pseudomonas 16S ribosomal DNA from ileal biopsies of children with Crohn's disease.

Molecular analysis of bacterial 16S rRNA genes has made a significant contribution to the identification and characterisation of bacterial flora in the human gut. In particular, this methodology has helped characterise bacterial families implicated in the aetiology of inflammatory bowel disease (IBD). In this study we have used a genus specific bacterial 16S PCR to investigate the prevalence and diversity of Pseudomonas species derived from the ileum of children with Crohn's disease (CD), and from control children with non-inflammatory bowel disease (non-IBD) undergoing their initial endoscopic examination. Fifty eight percent of CD patients (18/32) were positive using the Pseudomonas PCR, while significantly fewer children in the non-IBD group, 33% (12/36), were PCR positive for Pseudomonas (p<0.05, Fischer's exact test). Pseudomonas specific 16S PCR products from 13 CD and 12 non-IBD children were cloned and sequenced. Five hundred and eighty one sequences were generated and used for the comparative analysis of Pseudomonas diversity between CD and non-IBD patients. Pseudomonas species were less diverse in CD patients compared with non-IBD patients. In particular P.aeruginosa was only identified in non-IBD patients.

Non-structural protein NSP2 induces heterotypic antibody responses during primary rotavirus infection and reinfection in children.

Rotaviruses are the single most important causes of severe acute diarrhoea in children worldwide. Despite success in developing vaccines, there is still a lack of knowledge about many components of the immune response, particularly those to non-structural proteins. This study established radioimmunoprecipitation (RIP) assays using labeled G1P[8], G2P[4], and G4P[6] human rotaviruses to examine the spectrum and duration of rotavirus antibodies in sera collected sequentially for 18-36 months from 27 children after hospitalization for primary rotavirus gastroenteritis. Five children experienced rotavirus re-infections. Primary responses detected to non-structural protein NSP2 declined to baseline after 100-150 days. Responses were heterotypic between NSP2 of G1P[8] and G4P[8] rotaviruses. Re-infections after 465-786 days boosted antibody levels to NSP2of both serotypes, together with the appearance of anti-NSP2 to G2P[4], even though there was no evidence of infection with this serotype. We developed an enzyme-immunoassay to measure sequential levels of anti-NSP2 IgG and IgA, using recombinant (heterotypic) NSP2 derived from SA11 (G3P[2]). Anti-NSP2 IgG and IgA were detected in sera from 23/23 (100%) and 18/24 (75%) of children after primary infection, declined to baseline after 100-150 days, were boosted after rotavirus re-infections, and again declined to baseline 150 days later. Anti-NSP2 IgA was also detected after primary infection, in duodenal juice from 14/16 (87%), and faecal extract from 11/19 (57%) of children. Sequential estimation of anti-NSP2 EIA levels in sera could be a sensitive index of rotavirus infection and re-infection. The potential of anti-NSP2 to limit viral replication after re-infection deserves further study.

Changes in macromolecular transport appear early in Caco-2 cells infected with a human rotavirus.

OBJECTIVE: Rotavirus is a major cause of viral gastroenteritis, but its interaction with intestinal mucosa is poorly understood. The aim of this study was to examine the effect of Wa rotavirus (VP7 serotype 1) on barrier function in confluent Caco-2 cell monolayers. Wa is the most common serotype causing severe diarrhoea in humans. MATERIAL AND METHODS. We examined light and electron microscopic morphology, macromolecular transport, paracellular permeability, electrical parameters, disaccharidases and cytoskeletal structure in Wa- and in control sham-infected cells using a homologous human virus-cell system resembling human infection. RESULTS: During the first 48 h following Wa infection, there was no evidence of loss of integrity or of cytopathic effect in the monolayer. A significant cytopathic effect was noticed after 48 h. Further studies examined the initial 24-h period during which there was no evidence of significant injury. Apical-to-basolateral transcytosis of the macromolecule horseradish peroxidase (HRP) was selectively inhibited at 4 and 24 h post-infection with Wa. There were no significant changes in basolateral-to-apical transcytosis, endocytosis or in apical-to-apical recycling of HRP after Wa infection. G- and F-actin levels were significantly reduced within an area corresponding to the viroplasm in Wa-infected cells but not elsewhere in the monolayer. CONCLUSIONS: The early stages of rotavirus infection, before gross epithelial injury, are associated with a selective reduction in the apical uptake and transcytosis of macromolecules. We speculate that this is an epithelial defence mechanism.

Australian Rotavirus Surveillance Program annual report, 2007/08.

The National Rotavirus Reference Centre together with collaborating laboratories Australia-wide conducts a laboratory based rotavirus surveillance program. This report describes the types of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2007 to 30 June 2008, the first complete year of surveillance following introduction of rotavirus into the National Immunisation Program. Six hundred faecal samples from across Australia were examined using a combined approach of monoclonal antibody immunoassays and reverse transcription-polymerase chain reaction. Of the 419 confirmed as rotavirus positive, serotype G1 was the dominant serotype nationally, representing 52% of specimens, followed by serotype G2 (19.8%), serotype G9 (12.2%), and serotype G3 (11%). No serotype G4 strains were identified. All G1, G3 and G9 strains assayed for P genotype contained the P[8] genotype, while all G2 strains contained the P[4] genotype, except one G2 strain which possessed a P[8]. Uncommon rotavirus genotypes, G8 (n = 2) and P[9] (n = 2) were identified during this study period. There was no evidence of unexpected changes in serotype distribution during the first 12 months of rotavirus vaccine use in the National Immunisation Program.

Australian Rotavirus Surveillance Program: annual report, 2006-07.

The National Rotavirus Reference Centre, together with collaborating laboratories Australia-wide, conducts a laboratory based rotavirus surveillance program. This report describes the serotypes of rotavirus strains responsible for the hospitalisation of children with acute gastroenteritis during the period 1 July 2006 to 30 June 2007. One thousand and two faecal samples from across Australia were examined using a combined approach of monoclonal antibody immunoassays, reverse transcription-polymerase chain reaction and polyacrylamide gel analysis. Serotype G1 was the dominant serotype nationally, representing 36.7% of all strains, followed by serotype G9 (31.1%), and serotype G3 (23.3%). Serotype G2 represented less than 5% of strains, while no serotype G4 strains were identified. All G1, G3 and G9 strains assayed for P genotype contained the P[8] genotype, bar one G1 strain, which possessed a P[6]. Uncommon rotavirus genotypes, G8 (n = 1) and G12 (n = 2) were identified in children with acute gastroenteritis during this study period.