Introduction: rotavirus--from basic research to a vaccine

Knowledge and attitude regarding rotavirus and its vaccination among medical students in Karachi, Pakistan

Objective

The aim of this study is to determine the knowledge and attitude regarding rotavirus and its vaccination among medical students.

Study design

It is a cross sectional study.

Methods

Total 324 medical students were selected through stratified random sampling. A structured and validated questionnaire was used. Knowledge and attitude were recorded on scale. Independent t-test and ANVOA was used to determine the difference among gender and academic year. Regression and correlation analysis was done to determine the correlation of knowledge and attitude level with age and academic year of study. p value≤0.05 considered as statistically significant.

Results

Mean and standard deviation score of students were 7.88 ± 2.46 on knowledge scale and 4.16 ± 1.23 on attitude scale. Total 87% of students were aware of rotavirus and its vaccination. Both knowledge and attitude level were increased significantly with increasing year of study and age. After adjustment of covariate, Age and academic year of study were the significant factors in determining the scores on knowledge scale. (beta coefficient 0.056 with p-value 0.003 and 0.433 with p-value-0.000).

Conclusion

Medical students were appropriate knowledge about the rotavirus but attitude toward rotavirus vaccination is unsatisfactory. It should be a part of the curriculum of not just medical students but all students from high school to undergrad level regardless of the course they are enrolled in and also be advertised by the government.

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Medical students were appropriate knowledge about the rotavirus but attitude toward rotavirus vaccination is unsatisfactory.

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Age and academic year of study were the significant factors in determining the scores on knowledge scale.

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Rotavirus virus vacciantion and its importance should be a part of curriculum of all secondary students.

Effects of geographic and economic heterogeneity on the burden of rotavirus diarrhea and the impact and cost-effectiveness of vaccination in Pakistan

Globally, rotavirus is a leading cause of childhood diarrhea and related mortality. Although rotavirus vaccination has been introduced in many countries worldwide, there are numerous low- to middle-income countries that have not yet introduced. Pakistan is one of the countries with the highest number of rotavirus deaths in children under five years. Although rotavirus infection is almost universal among children, mortality is often a result of poor nutrition and lack of access to health care and other aspects of poverty. We assess the impact and cost-effectiveness of introducing childhood rotavirus vaccination in Pakistan. We use household data from the 2012-2013 Demographic Health survey in Pakistan to estimate heterogeneity in rotavirus mortality risk, vaccination benefits, and cost-effectiveness across geographic and economic groups. We estimate two-dose rotavirus vaccination coverage that would be distributed through a routine vaccination program. In addition, we estimate rotavirus mortality (burden), and other measures of vaccine cost-effectiveness and impact by subpopulations of children aggregated by region and economic status. Results indicate that the highest estimated regional rotavirus burden is in Sindh (3.3 rotavirus deaths/1000 births) and Balochistan (3.1 rotavirus deaths/1000 births), which also have the lowest estimated vaccination coverage, particularly for children living in the poorest households. In Pakistan, introduction could prevent 3061 deaths per year with current routine immunization patterns at an estimated $279/DALY averted. Increases in coverage to match the region with highest coverage (Islamabad) could prevent an additional 1648 deaths per year. Vaccination of children in the highest risk regions could result in a fourfold mortality reduction as compared to low risk children, and children in the poorest households have a three to four times greater mortality reduction benefit than the richest. Based on the analysis presented here, the benefits and cost-effectiveness of rotavirus vaccination can be maximized by reaching economically and geographically vulnerable children.

[Sensitivity and specificity of the VIKIA Rota-Adeno immuno-chromatographic test (bioMérieux) and the ELISA IDEIA Rotavirus kit (Dako) compared to genotyping]

The performances of two diagnostic tests for rotavirus infection in stool samples were evaluated during a prospective study in children of less than 36 months in child-care centers of Lyon from November 2004 to May 2005. The VIKIA Rota-Adeno immuno-chromatographic test (bioMérieux) and the ELISA IDEIA Rotavirus kit (Dako) were compared with a referral method, the genotyping. Fifty-seven stool samples were collected and analyzed by RT-PCR. The virus genome was detected in 29 samples. The most frequent genotypic combinations were G9P[8] with a prevalence of 75.9%. Sensitivity and specificity of the VIKIA Rota-Adeno test and the ELISA IDEIA Rotavirus kit were strictly comparable and very good: 96.6% (83.0; 99.9) and 96.4% (81.6; 99.9), respectively. The immuno-chromatographic technique were in concordance with the ELISA tests in 93.6% of cases. Thus, the VIKIA Rota-Adeno test is a good alternative for the occasional analysis of stool samples in ambulatory practice.

Évaluation de sept réactifs d'immunochromatographie pour détecter les rotavirus humains dans les selles

Seven commercially available immunochromatographic assays were tested for the rapid detection of group A rotaviruses in fecal samples compared to a enzyme immunoassay (Argene). Detection of rotaviruses in 80 ELISA positive frozen stool samples showed rates superior to 90% for three reagents (Rota Strip (Cypress Diagnostics), 98.8%; Rotascreen (Microgen), 95.0%; VIKIA Rota/Adeno (bioMérieux), 92.5%); from 82.5% to 88.8% for three others (Diarlex with centrifugation (Orion Diagnostica), 88.8%; Combo Rota/Adeno (All Diag), 87.5%; Rota/Adeno Combi Stick (bmd), 82.5%) and only 70.0% for Diarlex with filtration vial (Orion Diagnostica). The evaluation of the specificity, performed on one hundred fresh rotavirus negative stools, did not show any false positives with any assay. Analysis of the different technical features of these tests showed that they are quick and suitable for a clinical laboratory and do not require expensive equipment.

The VP6 protein of rotavirus interacts with a large fraction of human naive B cells via surface immunoglobulins

Immunity to human group A rotavirus (RV), a major cause of viral gastroenteritis in infants, involves B lymphocytes that provide RV-specific antibodies. Additionally, some arguments suggest that naive B cells could be implicated in the first steps of the immune response against RV. The aim of our study was to analyze the interaction of VP6 and VP7 RV capsid proteins with human B cells depending on the immune status of the individual, i.e., naive or RV experienced. For this purpose, a two-color virus-like particle flow cytometry assay was devised to evaluate the blood B-lymphocyte reactivity to VP6 and VP7 proteins from healthy RV-exposed adults, recently infected infants, and neonates at birth. Both VP6 and VP7 interactions with B cells were mediated by surface immunoglobulins and probably by their Fab portions. VP7-reactive B lymphocytes were mainly detected from RV-experienced patients and almost exclusively in the CD27-positive memory cell fraction. Conversely, VP6-reactive B lymphocytes were detected at similar and high frequencies in adult, infant, and neonate samples. In adult samples, VP6 reacted with about 2% of the CD27-negative (CD27(neg)) naive B cells. These results demonstrated that the VP6 RV protein interacted with a large fraction of naive B lymphocytes from both adults and neonates. We propose that naive B cell-VP6 interaction might influence the strength and quality of the acquired immune response and should be considered for elaborating RV vaccine strategies.

Epidemiological features of rotavirus infection in Goiânia, Goiás, Brazil, from 1986 to 2000

A total of 2,605 faecal specimens from children up to 10 years old with or without diarrhoea were collected. Samples were obtained from 1986 to 2000 in hospitals, outpatient clinics and day-care centers in Goiânia, Goiás. Two methodologies for viral detection were utilized: a combined enzyme immunoassay for rotavirus and adenovirus and polyacrylamide gel electrophoresis. Results showed 374 (14.4%) faecal specimens positive for Rotavirus A, most of them collected from hospitalized children. A significant detection rate of rotavirus during the period from April to August, dry season in Goiânia, and different frequencies of viral detection throughout the years of study were also observed. Rotavirus was significantly related to hospitalization and to diarrhoeal illness in children up to 24 months old. This study reinforces the importance of rotavirus as a cause of diarrhoea in children and may be important in regards to the implementation of rotavirus vaccination strategies in our country.

Antibody-secreting cell responses to rotavirus proteins in gnotobiotic pigs inoculated with attenuated or virulent human rotavirus

Because of their similarities to infants in mucosal immune responses and their susceptibility to human rotavirus (HRV) diarrhea, gnotobiotic pigs provide a useful model for rotaviral disease. In this study, we performed quantitative enzyme-linked immunospot (ELISPOT) assays to measure local and systemic isotype-specific antibody-secreting cell (ASC) responses to individual structural (VP4, VP6, and VP7) and nonstructural (NSP3 and NSP4) proteins of Wa HRV. The Spodoptera frugiperda cells expressing each recombinant baculovirus HRV protein were formalin fixed and used as antigen for ELISPOT assays. Neonatal gnotobiotic pigs were orally inoculated once with virulent Wa (WaV) or three times with attenuated Wa (WaA) HRV or mock inoculated (Mock) and then were challenged with virulent Wa (WaV/PC) 28 days after the first inoculation. The ASCs from intestinal and systemic lymphoid tissues of pigs from each group were quantitated by ELISPOT assay at the day of challenge, at postinoculation day 28 (WaV, WaA, and Mock) or at postchallenge day (PCD) 7 (WaV+WaV/PC, WaA+WaV/PC, and Mock+WaV/PC). In all virus-inoculated pigs, regardless of the inoculum, lymphoid tissue, or isotype, VP6 induced the highest numbers of ASCs, followed by VP4; ASCs specific for VP7, NSP3, and NSP4 were less numerous. At challenge, total HRV- and HRV protein-specific immunoglobulin A (IgA) and IgG ASCs in intestinal lymphoid tissues were significantly greater in WaV- than in WaA-inoculated pigs, and WaV pigs were fully protected against diarrhea postchallenge, whereas the WaA pigs were partially protected. At PCD 7, there were no significant differences in ASC numbers for any HRV proteins between the WaV+WaV/PC and WaA+WaV/PC groups.

[Rotavirus infection in Brazil: epidemiology and challenges for its control]

Worldwide, rotaviruses account for 600,000 to 870,000 deaths per year among infants and young children. In Brazil, rotaviruses were first seen in 1976 by scanning electron microscopy of stool samples from diarrheic infants in Belém, Pará. Hospital-based studies have shown that rotaviruses are associated with 12-42% of cases of acute diarrhea. In addition, community-based studies yielded an average of 0.25 rotavirus-related diarrheal episodes per child per year. G types 1 to 4 account for about two-thirds of circulating strains, but the (unusual) P[8],G5 genotype has been claimed to cause over 10% of rotavirus diarrheal episodes. It has been shown that over 70% of children develop rotavirus antibodies by the age of 4-5 years. The tetravalent rhesus-human rotavirus vaccine (RRV-TV) conferred 35% protection according to a two-year follow-up study in Belém, Pará, Brazil, but reached an efficacy of 60% during the first year of life. RRV-TV was also shown to be 75% protective against very severe gastroenteritis in northern Brazil. Vaccination with RRV-TV has been suspended recently in the United States because of the detection of intussusception as a side effect. Therefore, further vaccine trials in Brazil will probably involve rotavirus candidate vaccines other than RRV-TV.

Rotavirus disease and its prevention in infants and children

Rotavirus disease causes immense morbidity and mortality in developing countries. In the United States, mortality is very rare, but the health care and societal costs of rotavirus-related morbidity exceed one billion dollars annually A new vaccine that prevents the illness recently was marketed in the United States. Economic issues surround national recommendations for its use. Economic, safety, and effectiveness issues will be resolved only with surveillance systems that document the effectiveness of immunization programs and their cost-effectiveness.

Bacterial expression of the major antigenic regions of porcine rotavirus VP7 induces a neutralizing immune response in mice

The outer capsid protein of rotavirus, VP7, is a major neutralization antigen. A chimeric protein comprising Escherichia coli (E. coli) outer membrane protein A (OmpA) and part of porcine rotavirus VP7 containing all three antigenic regions (217 amino acids) was expressed in Salmonella and E. coli as an outer-membrane associated protein. Mice immunized intraperitoneally or orally, respectively, with live E. coli or Salmonella cells expressing this chimeric protein produced antibodies against native VP7 as determined by enzyme-linked immunosorbent assays and neutralization tests. This indicates that the VP7 fragment from a porcine rotavirus which is antigenically similar to human rotavirus serotype 3, when expressed in bacteria as a chimeric protein, can form a structure resembling its native form at least in some of the major neutralization domains. These results indicate that the use of a live bacterial vector expressing rotavirus VP7 may represent a strategy for the development of vaccines against rotavirus-induced diarrhoea in infants.

Production of reovirus type-1 and type-3 from Vero cells grown on solid and macroporous microcarriers

Two strains of reovirus were propagated in Vero cells grown in stationary or microcarriers cultures. Vero cells grown as monolayers on T-flasks or in spinner cultures of Cytodex-1 or Cultispher-G microcarriers could be infected with reovirus serotype 1, strain Lang (T1L), and serotype 3, strain Dearing (T3D). A regime of intermittent low speed stirring at reduced culture volume was critical to ensure viral infection of cells in microcarrier cultures. The virus titre increased by 3 to 4 orders of magnitude over a culture period of 150 h. Titres of the T3D reovirus strain were higher (43%) compared to those of the T1L strain in all cultures. Titres were significantly higher in T-flask and Cytodex-1 microcarrier cultures compared to Cultispher-G cultures with respect to either reovirus type. The viral productivity in the microcarrier cultures was dependent upon the multiplicity of infection (MOI) and the cell/bead ratio at the point of infection. A combination of high MOI (5 pfu/cell) and high cell/bead loading (>400 for Cytodex-1 and >1,000 for Cultispher-G) resulted in a low virus productivity per cell. However, at low MOI (0.5 pfu/cell) the virus productivity per cell was significantly higher at high cell/bead loading in cultures of either microcarrier type. The maximum virus titre (8.5 x 10(9) pfu/mL) was obtained in Cytodex-1 cultures with a low MOI (0.5 pfu/cell) and a cell/bead loading of 1,000. The virus productivity per cell in these cultures was 4,000 pfu/cell. The lower viral yield in the Cultispher-G microcarrier cultures is attributed to a decreased accessibility of the entrapped cells to viral infection. The high viral productivity from the Vero cells in Cytodex-1 cultures suggests that this is a suitable system for the development of a vaccine production system for the Reoviridae viruses.

Impact of rotavirus disease in Spain: an estimate of hospital admissions due to rotavirus

The epidemiology of rotavirus infection in Spain was investigated using information from existing surveillance systems. Reports from laboratories and data on hospital admissions were used to estimate the number of hospital admissions due to rotavirus infection. Between January 1989 and December 1995 there were 8265 reports of rotavirus identification in the Sistema de Información Microbiológica, a voluntary national laboratory surveillance system. Where age was reported, 89.2% were in children under 5 y old. This represents 21.8% of all pathogens identified in faecal specimens in children of this age group. Between January and December 1994 there were 5639 admissions coded as "infectious intestinal disease" and 8225 as "non-infective gastroenteritis" in children under 5 y of age in the Conjunto Mínimo Básico de Datos, an obligatory hospital admissions surveillance system which covers 83% of public hospitals. Using regression analysis of admission data and laboratory reports it was estimated that rotavirus infection accounted for 3519 (25.3%) of the hospital admissions. We estimate that 4239 admissions attributable to rotavirus occurred in children under 5 y of age in Spain in 1994, a rate of 2.5/1000 population in this age group. These estimates are lower than those published for other countries, where the burden of disease is considered high enough to warrant a national vaccination programme. A cost-effectiveness study with Spanish information is essential before embarking on a national vaccination programme.