Host genetic factors affect susceptibility to norovirus infections in Burkina Faso

Associations Between Histo-blood Group Antigen Status in Mother-Infant Dyads and Infant Oral Rotavirus Vaccine Immunogenicity in Rural Zimbabwe

BACKGROUND

Histo-blood group antigen (HBGA) phenotypes may contribute to poor oral rotavirus vaccine (RVV) immunogenicity, since rotavirus binds intestinal epithelial HBGA glycans, while maternal HBGA status shapes breastmilk composition, which influences the composition of the infant microbiome. We investigated associations between maternal/infant HBGA phenotypes and RVV immunogenicity in rural Zimbabwe.

METHODS

We undertook salivary FUT2/FUT3 phenotyping in mother-infant pairs. Serum anti-rotavirus immunoglobulin A was measured by enzyme-linked immunosorbent assay. We explored adjusted associations between FUT2/FUT3 status and RVV seroconversion (primary outcome, n = 322) and seropositivity and geometric mean titer (secondary outcomes, n = 776).

RESULTS

Infants of FUT2- or FUT3-positive women were less likely to seroconvert post-RVV than infants of FUT2- or FUT3-negative women (FUT2 positive [20.1%] vs FUT2 negative [27.5%]: adjusted relative risk [aRR], 0.47; 95% CI, .26-.82; P = .008; FUT3 positive [18.1%] vs FUT3 negative [30.0%]: aRR, 0.45; 95% CI, .25-.78; P = .005). When compared with FUT2-positive infants with FUT2-positive mothers, FUT2-positive infants with FUT2-negative mothers were twice as likely to seroconvert (36.8% vs 21.9%; aRR, 2.12; 95% CI, 1.23-3.63; P = .006). When compared with FUT3-positive infants with FUT3-positive mothers, FUT3-positive infants with FUT3-negative mothers were 3 times as likely to seroconvert (48.3% vs 18.2%; aRR, 2.99; 95% CI, 1.82-4.90; P < .001).

CONCLUSIONS

Maternal and infant FUT2 and FUT3 status influences infant RVV immunogenicity.

Global burden and trends of norovirus-associated diseases from 1990 to 2021 an observational trend study

Background

Norovirus remains a significant viral cause of waterborne and foodborne gastroenteritis outbreaks and epidemics worldwide. The burden of norovirus extends across different income settings.

Methods

Leveraging secondary data from the 2021 Global Burden of Diseases Study, our analysis spanned the period from 1990 to 2021 to assess the burden of norovirus-associated diseases (NADs). We utilized descriptive statistics to examine global mortality rates and disability-adjusted life years (DALYs). For trend analysis, we employed annual percentage change (EAPC) through linear regression and applied Joinpoint analysis to identify significant changes over time. A comprehensive age-period-cohort model evaluated the key mortality risk factors. Furthermore, a Bayesian age-period-cohort analysis was conducted to forecast trends up to 2035, providing valuable insights for policy formulation and resource allocation.

Results

In 2021, the global age-standardized mortality rate (ASMR) for NADs was 1.62 per 100,000 population (95% UI: 0.35 to 2.91), while the age-standardized DALY rates (ASDR) was 79.02 years per 100,000 population (95% UI: 26.61 to 132.26). A downward trend was observed in most regions and countries, with EAPC of -4.29% (95% UI: -4.53 to -4.05) for ASMR and -4.40% (95% UI: -4.62 to -4.19) for ASDR from 1990 to 2021. Notably, children under 5 years old had considerably higher ASDR: 475.52 years (95% UI: 160.73 to 893.72) per 100,000 for males and 335.44 years (95% UI: 112.29 to 623.48) per 100,000 for females. Mortality risk from NADs escalated with age, with a peak of 69.27 (95% CI: 64.04 to 74.92) per 100,000 for the under-five age group, and 11.38 (95% CI: 10.59 to 12.22) per 100,000 for individuals over 95 years. Bayesian Age-Period Cohort projections indicate a continued decline in ASMR and ASDR through 2035.

Discussion

Between 1990 and 2021, ASMR and ASDR for NADs significantly declined due to public health interventions, vaccination, and improved sanitation. However, norovirus remains highly contagious, especially among children and the older adult. Projections suggest a continued decrease in the burden of such diseases by 2035. To further reduce this burden, preventive measures like vaccination and infection control strategies are essential for high-risk populations, alongside ongoing research into norovirus epidemiology and transmission dynamics.

The attachment factors and attachment receptors of human noroviruses

Human noroviruses (HuNoVs) are the leading etiological agent causing the worldwide outbreaks of acute epidemic non-bacterial gastroenteritis. Histo-blood group antigens (HBGAs) are commonly acknowledged as cellular receptors or co-receptors for HuNoVs. However, certain genotypes of HuNoVs cannot bind with any HBGAs, suggesting potential additional co-factors and attachment receptors have not been identified yet. In addition, food items, such as oysters and lettuce, play an important role in the transmission of HuNoVs. In the past decade, a couple of attachment factors other than HBGAs have been identified and analyzed from foods and microbiomes. Attachment factors exhibit potential as inhibitors of viral binding to receptors on host cells. Therefore, it is imperative to further characterize the attachment factors for HuNoVs present in foods to effectively control the spread of HuNoVs within the food chain. This review summarizes the potential attachment factors/receptors of HuNoVs in humans, foods, and microbiome.

Modifiable and Non-Modifiable Factors That Affect Human Milk Oligosaccharides Composition

Human milk, the gold standard in infant nutrition, is a unique fluid that provides essential nutrients such as lactose, lipids, proteins, and free oligosaccharides. While its primary role is nutritional, it also protects against pathogens. This protection mainly comes from immunoglobulins, with human milk oligosaccharides (HMOs) providing additional support by inhibiting pathogen binding to host cell ligands. The prebiotic and immune-modulatory activity of HMOs strongly depends on their structure. Over 200 individual structures have been identified so far, with the composition varying significantly among women. The structure and composition of HMOs are influenced by factors such as the Lewis blood group, secretor status, and the duration of nursing. HMO profiles are heavily influenced by maternal phenotypes, which are defined based on the expression of two specific fucosyltransferases. However, recent data have shown that HMO content can be modified by various factors, both changeable and unchangeable, including diet, maternal age, gestational age, mode of delivery, breastfeeding frequency, and race. The first part of this overview presents the historical background of these sugars and the efforts by scientists to extract them using the latest chromatography methods. The second part is divided into subchapters that examine modifiable and non-modifiable factors, reviewing the most recent articles on HMO composition variations due to specific reasons and summarizing potential future challenges in conducting these types of studies.

Geographical distribution of enteric pathogenic viruses in Burkina Faso: a systematic review and meta-analysis

BACKGROUND

Viruses, which are transmitted mainly via the digestive tract, are responsible for the high morbidity and mortality of diseases, particularly in low-income countries. Although several studies have established the prevalence and characterization of various enteric viruses in Burkina Faso, to date, no aggregate data have been released.

OBJECTIVE

Our objective was to describe the available data on the prevalence and circulating genotypes of enteric pathogen viruses responsible for human infections in Burkina Faso by carrying out a systematic review and meta-analysis.

METHODS

Potentially relevant studies were identified by a search of PubMed, ScienceDirect, Google Scholar, university libraries and by a manual search of the reference lists of identified studies. The search with no restrictions on language or age was limited to studies conducted only in Burkina. Study selection, data extraction, and methodological quality of the included studies were performed independently by two investigators. Heterogeneity between studies was assessed using the Cochrane Q test and I2 test statistics based on the random effects model. Comprehensive meta-analysis (CMA 3.7) was employed to compute the pooled prevalence of pathogens identified in the studies.

RESULTS

Forty-three (43) studies reporting 4,214 diagnosed cases in all aged human populations were selected. Overall, 72.6% of the pathogens diagnosed were gastroenteritis, and 27.2% were entero-transmissible hepatitis viruses. Rotavirus was the most common cause of human viral gastroenteritis, accounting for 27.7% (95% CI: 20.9 - 35.8) of the cases, followed by norovirus (16% (95% CI: 12.25 - 20.6)) and sapovirus (11.2% (95% CI: 6.2 - 19.4)). In terms of human entero-transmissible infections, hepatitis A virus (HAV) was the most prevalent (52% [95% CI: 14.2-87.7] of total antibodies), followed by hepatitis E virus (HEV) (28.3% [95% CI: 17.7-42]).

CONCLUSIONS

This study highlights the substantial burden of viral enteric infections and highlights the need for more molecular epidemiological studies to improve preventive measures against these viruses.

Rotavirus vaccines in Africa and Norovirus genetic diversity in children aged 0 to 5 years old: a systematic review and meta-analysis : Rotavirus vaccines in Africa and Norovirus genetic diversity

Noroviruses are the second leading cause of death in children under the age of 5 years old. They are responsible for 200 million cases of diarrhoea and 50,000 deaths in children through the word, mainly in low-income countries. The objective of this review was to assess how the prevalence and genetic diversity of noroviruses have been affected by the introduction of rotavirus vaccines in Africa. PubMed, Web of Science and Science Direct databases were searched for articles. All included studies were conducted in Africa in children aged 0 to 5 years old with gastroenteritis. STATA version 16.0 software was used to perform the meta-analysis. The method of Dersimonian and Laird, based on the random effects model, was used for the statistical analyses in order to estimate the pooled prevalence's at a 95% confidence interval (CI). Heterogeneity was assessed by Cochran's Q test using the I2 index. The funnel plot was used to assess study publication bias. A total of 521 studies were retrieved from the databases, and 19 were included in the meta-analysis. The pooled norovirus prevalence's for pre- and post-vaccination rotavirus studies were 15% (95 CI, 15-18) and 13% (95 CI, 09-17) respectively. GII was the predominant genogroup, with prevalence of 87.64% and 91.20% respectively for the pre- and post-vaccination studies. GII.4 was the most frequently detected genotype, with rates of 66.84% and 51.24% respectively for the pre- and post-vaccination studies. This meta-analysis indicates that rotavirus vaccination has not resulted in a decrease in norovirus infections in Africa.

Current trends and new approaches for human norovirus replication in cell culture: a literature review

Human norovirus (HuNoV) is one of the world's leading causes of acute gastroenteritis. At present, effective reproduction of the virus in cell cultures remains a challenge for virologists, as there is a lack of a permissive cell line that allows the entire viral life cycle to be reproduced. This is a barrier to the study of the HuNoV life cycle, its tropism, and virus-host interactions. It is also a major hurdle for the development of viral detection platforms, and ultimately for the development of therapeutics. The lack of an inexpensive, technically simple, and easily implemented cultivation method also negatively affects our ability to evaluate the efficacy of a variety of control measures (disinfectants, food processes) for human norovirus. In the process of monitoring this pathogen, it is necessary to detect infectious viral particles in water, food, and other environmental samples. Therefore, improvement of in vitro replication of HuNoV is still needed. In this review, we discuss current trends and new approaches to HuNoV replication in cell culture. We highlight ways in which previous research on HuNoV and other noroviruses has guided and influenced the development of new HuNoV culture systems and discuss the improvement of in vitro replication of HuNoV.

A household survey of intrafamily norovirus transmission

Norovirus (NoV) is a leading cause of epidemic and sporadic gastroenteritis in people of all ages. Humans are the primary source of NoV and household contact is one of the risk factors for NoV transmission. However, the mechanisms underlying person-to-person NoV transmission are poorly understood. Here we conducted a survey to profile the frequency and characteristics of intrafamily NoV transmission. Stool samples were collected every week from three households between 2016 and 2020; the total number of samples was 1105. The detection of NoV and the genotyping were performed by reverse transcription-polymerase chain reaction targeting the capsid region and direct sequencing methods. NoV was detected in 3.4% of all samples. Eight NoV genotypes were identified. The most common genotype was GII.17, followed in order by GII.6, GI.6, GII.4, GI.3, and GI.2/GI.8/GI.9. Most NoV-positive samples were obtained from asymptomatic individuals. The highest number of NoV transmissions was found in household 3 (6 infections), followed by household 2 (2 infections), while household 1 had no NoV transmission, suggesting that asymptomatic NoV carriers play a major role in infection as NoV reservoirs in the households. Further clarification of the mode of infection will contribute to improved understanding and an appropriate prevention.

Assessment of the influence of ABO blood groups on oral cholera vaccine immunogenicity in a cholera endemic area in Zambia

BACKGROUND

Histo-blood group antigens (HBGAs) which include the ABO and Lewis antigen systems have been known for determining predisposition to infections. For instance, blood group O individuals have a higher risk of severe illness due to V. cholerae compared to those with non-blood group O antigens. We set out to determine the influence that these HBGAs have on oral cholera vaccine immunogenicity and seroconversion in individuals residing within a cholera endemic area in Zambia.

METHODOLOGY

We conducted a longitudinal study nested under a clinical trial in which samples from a cohort of 223 adults who were vaccinated with two doses of Shanchol™ and followed up over 4 years were used. We measured serum vibriocidal geometric mean titers (GMTs) at Baseline, Day 28, Months 6, 12, 24, 30, 36 and 48 in response to the vaccine. Saliva obtained at 1 year post vaccination was tested for HBGA phenotypes and secretor status using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Of the 133/223 participants included in the final analysis, the majority were above 34 years old (58%) and of these, 90% were males. Seroconversion rates to V. cholerae O1 Inaba with non-O (23%) and O (30%) blood types were comparable. The same pattern was observed against O1 Ogawa serotype between non-O (25%) and O (35%). This trend continued over the four-year follow-up period. Similarly, no significant differences were observed in seroconversion rates between the non-secretors (26%) and secretors (36%) against V. cholerae O1 Inaba. The same was observed for O1 Ogawa in non-secretors (22%) and the secretors (36%).

CONCLUSION

Our results do not support the idea that ABO blood grouping influence vaccine uptake and responses against cholera.

Maternal and child FUT2 and FUT3 status demonstrate relationship with gut health, body composition and growth of children in Bangladesh

Fucosyltransferase 2 (FUT2) and 3 (FUT3) may influence host biological functions. We aim to assess the relationship between maternal and child FUT2 (Secretor) and FUT3 (Lewis) status with growth, body composition, gut health and histologic features in Bangladeshi children. We conducted a case-control study where secretor and Lewis status were ascertained from saliva samples of 408 mother-child dyads. Upper-arm fat area estimate (UFE) and total upper arm area (TUA) were found higher among children of Lewis negative mothers (p = 0.01 and p = 0.07, respectively). Changes in UFE after nutrition intervention were significantly greater among Lewis positive children than those of negative for Lewis (p = 0.05). Significant differences were observed for child UFE based on secretor and Lewis status of the mothers (p = 0.04). Lewis positive children had greater changes in WAZ (p = 0.07) and WLZ (p = 0.02) than Lewis negative children at the end of nutrition intervention. Fecal Reg1B was elevated in secretor positive children compared to their counterparts (p = 0.03). Lewis negative children had higher concentrations of MPO compared to Lewis positive children (p = 0.08). We also observed a higher frequency of subtotal villous atrophy among secretor negative and Lewis positive children (p = 0.09 and p = 0.01, respectively) than those of their counterparts. The findings provide insights for further studies to elucidate causal influences.

ABO blood groups and the risk of SARS-CoV-2 infection

There is no doubt that genetic factors of the host play a role in susceptibility to infectious diseases. An association between ABO blood groups and SARS-CoV-2 infection as well as the severity of COVID-19 has been suggested relatively early during the pandemic and gained enormously high public interest. It was postulated that blood group A predisposes to a higher risk of infection as well as to a much higher risk of severe respiratory disease and that people with blood group O are less frequently and less severely affected by the disease. However, as to the severity of COVID-19, a thorough summary of the existing literature does not support these assumptions in general. Accordingly, at this time, there is no reason to suppose that knowledge of a patient's ABO phenotype should directly influence therapeutical decisions in any way. On the other hand, there are many data available supporting an association between the ABO blood groups and the risk of contracting SARS-CoV-2. To explain this association, several interactions between the virus and the host cell membrane have been proposed which will be discussed here.

Association of histo-blood group antigens and predisposition to gastrointestinal diseases

Infectious gastroenteritis is a common illness afflicting people worldwide. The two most common etiological agents of viral gastroenteritis, rotavirus and norovirus are known to recognize histo-blood group antigens (HBGAs) as attachment receptors. ABO, Lewis, and secretor HBGAs are distributed abundantly on mucosal epithelia, red blood cell membranes, and also secreted in biological fluids, such as saliva, intestinal content, milk, and blood. HBGAs are fucosylated glycans that have been implicated in the attachment of some enteric pathogens such as bacteria, parasites, and viruses. Single nucleotide polymorphisms in the genes encoding ABO (H), fucosyltransferase gene FUT2 (Secretor/Se), FUT3 (Lewis/Le) have been associated with changes in enzyme expression and HBGAs production. The highly polymorphic HBGAs among different populations and races influence genotype-specific susceptibility or resistance to enteric pathogens and its epidemiology, and vaccination seroconversion. Therefore, there is an urgent need to conduct population-based investigations to understand predisposition to enteric infections and gastrointestinal diseases. This review focuses on the relationship between HBGAs and predisposition to common human gastrointestinal illnesses caused by viral, bacterial, and parasitic agents.

Intestinal Norovirus Binding Patterns in Nonsecretor Individuals

Human norovirus (HuNoV) infection is associated with an active FUT2 gene, which characterizes the secretor phenotype. However, nonsecretor individuals are also affected by HuNoV infection although in a lesser proportion. Here, we studied GII.3, GII.4, and GII.17 HuNoV interactions in nonsecretor individuals using virus-like particles (VLPs). Only GII.4 HuNoV specifically interacted with nonsecretor saliva. Competition experiments using histo-blood group antigen (HBGA)-specific monoclonal antibodies (MAbs) demonstrate that GII.4 VLPs recognized the Lewis a (Le^a) antigen. We also analyzed HuNoV VLP interactions on duodenum tissue blocks from healthy nonsecretor individuals. VLP binding was observed for the three HuNoV genotypes in 10 of the 13 individuals, and competition experiments demonstrated that VLP recognition was driven by an interaction with the Le^a antigen. In 3 individuals, binding was restricted to either GII.4 alone or GII.3 and GII.17. Finally, we performed a VLP binding assay on proximal and distal colon tissue blocks from a nonsecretor patient with Crohn's disease. VLP binding to inflammatory tissues was genotype specific since GII.4 and GII.17 VLPs were able to interact with regenerative mucosa, whereas GII.3 VLP was not. The binding of GII.4 and GII.17 HuNoV VLPs was linked to Le^a in regenerative mucosae from the proximal and distal colon. Overall, our data clearly showed that Le^a has a pivotal role in the recognition of HuNoV in nonsecretors. We also showed that Le^a is expressed in inflammatory/regenerative tissues and interacts with HuNoV in a nonsecretor individual. The physiological and immunological consequences of such interactions in nonsecretors have yet to be elucidated. IMPORTANCE Human norovirus (HuNoV) is the main etiological agent of viral gastroenteritis in all age classes. HuNoV infection affects mainly secretor individuals where ABO(H) and Lewis histo-blood group antigens (HBGAs) are present in the small intestine. Nonsecretor individuals, who only express Lewis (Le) antigens, are less susceptible to HuNoV infection. Here, we studied the interaction of common HuNoV genotypes (GII.3, GII.4, and GII.17) in nonsecretor individuals using synthetic viral particles. Saliva binding assays showed that only GII.4 interacted with nonsecretor saliva via the Lewis a (Le^a) antigen Surprisingly, the three genotypes interacted with nonsecretor enterocytes via the Le^a antigen on duodenal tissue blocks, which were more relevant for HuNoV/HBGA studies. The Le^a antigen also played a pivotal role in the recognition of GII.4 and GII.17 particles by inflammatory colon tissue from a nonsecretor Crohn's disease patient. The implications of HuNoV binding in nonsecretors remain to be elucidated in physiological and pathological conditions encountered in other intestinal diseases.

Norovirus Genetic Diversity in Children under Five Years Old with Acute Diarrhea in Mozambique (2014-2015)

Norovirus (NoV) is the second most important cause of viral diarrheal disease in children worldwide after rotavirus and is estimated to be responsible for 17% of acute diarrhea in low-income countries. This study aimed to identify and report NoV genotypes in Mozambican children under the age of five years with acute diarrhea. Between May 2014 and December 2015, stool specimens were collected within the Mozambique Diarrhea National Surveillance (ViNaDia) and tested for NoV genogroups I (GI) and II (GII) using conventional reverse transcriptase-polymerase chain reaction (RT-PCR). Partial capsid and RNA-dependent RNA polymerase (RdRp) nucleotide sequences were aligned using the Muscle tool, and phylogenetic analyses were performed using MEGA X. A total of 204 stool specimens were tested for NoV. The detection rate of NoV was 14.2% (29/204). The presence of NoV was confirmed, by real-time RT-PCR (RT-qPCR), in 24/29 (82.8%) specimens, and NoV GII predominated (70.8%; 17/24). NoV GII.4 Sydney 2012[P31] was the predominant genotype/P-type combination detected (30.4%; 7/23). This is the first study which highlights the high genetic diversity of NoV in Mozambican children and the need to establish a continuous NoV surveillance system.

Recombinant Noroviruses Circulating in Spain from 2016 to 2020 and Proposal of Two Novel Genotypes within Genogroup I

Noroviruses are the leading cause of sporadic cases and outbreaks of viral gastroenteritis. For more than 20 years, most norovirus infections have been caused by the pandemic genotype GII.4, yet recent studies have reported the emergence of recombinant strains in many countries. In the present study, 4,950 stool samples collected between January 2016 and April 2020 in Valencia, Spain, from patients with acute gastroenteritis were analyzed to investigate the etiological agent. Norovirus was the most frequently detected enteric virus, with a positivity rate of 9.5% (471/4,950). Among 224 norovirus strains characterized, 175 belonged to genogroup II (GII) and 49 belonged to GI. Using dual genotyping based on sequencing of the open reading frame 1 (ORF1)/ORF2 junction region, we detected 25 different capsid-polymerase-type associations. The most common GII capsid genotype was GII.4 Sydney 2012, followed by GII.2, GII.3, GII.6, and GII.17. A high prevalence of recombinant strains (90.4%) was observed among GII infections between 2018 and 2020. GII.4 Sydney[P16] was the predominant genotype from 2019 to 2020. In addition, GII.P16 polymerase was found harbored within six different capsid genes. GI.4 and GI.3 were the predominant genotypes in genogroup I, in which recombinant strains were also found, such as GI.3[P10], GI.3[P13], and GI.5[P4]. Interestingly, applying the criterion of 2 times the standard deviation, we found that 12 sequences initially classified as GI.3 may represent two new tentative genotypes in genogroup I, designated GI.10 and GI.11. This study shows the extensive diversity of recombinant noroviruses circulating in Spain and highlights the role of recombination events in the spread of noroviruses. IMPORTANCE Human noroviruses are the most common cause of viral diarrhea. There are no approved vaccines to prevent their infections yet, which would be very useful to protect infants, small children, and the elderly in residential institutions. These viruses are extremely contagious and can be transmitted by contaminated food and water as well as directly from person to person. Molecular surveillance and epidemiology of norovirus infections allow the identification of the most common viral strains in different geographical areas over time. Noroviruses show wide genetic variability due to a high rate of mutations but also due to genomic recombinations, as we demonstrate in this study. We have detected 25 different viral capsid-polymerase gene associations among 224 norovirus strains characterized in Spain between January 2016 and April 2020, including two tentative new capsid genotypes in genogroup I.

Fucosyltransferase 2: A Genetic Risk Factor for Intestinal Diseases

The fucosyltransferase 2 gene (FUT2) mediates the synthesis of histoblood group antigens (HBGA) that occur in vivo from multiple organs, particularly on the surface of intestinal epithelial cells and body fluids. To date, many studies have demonstrated that the interaction of HBGA with the host microbiota is the cause of pathogenesis of intestinal diseases, making FUT2 non-secretor a risk factor for inflammatory bowel disease (IBD) due to the lack of HBGA. As HBGA also acts as an attachment site for norovirus (NoV) and rotavirus (RV), the non-secretor becomes a protective factor for both viral infections. In addition, the interaction of norovirus and rotavirus with symbiotic bacteria has been found to play an important role in regulating enteroviral infection in IBD. Given the current incomplete understanding of the complex phenomenon and the underlying pathogenesis of intestinal diseases such as IBD, it has recently been hypothesized that the FUT2 gene regulates intestinal bacteria through attachment sites, may help to unravel the role of FUT2 and intestinal flora in the mechanism of intestinal diseases in the future, and provide new ideas for the prevention and treatment of intestinal diseases through more in-depth studies.

FUT2 gene as a genetic susceptible marker of infectious diseases: A Review

Some blood group antigens are reported as a susceptibility marker for some diseases. For instance, HBGA (Histo-blood group antigen) which is controlled by gene FUT2 also considered as a susceptible marker. The FUT2 gene which exhibits the expression of alpha-1, 2-L-fucosyltransferase enzyme also leads to HBGA expression for the gut, and it provides a composition of the phenotypical profile that exists in some populations with unique histories of evolution and it can be considered as a marker of the genetic population. It is found to have an association with many diseases which is discussed in this review. Polymorphic mutations are known to inhibit and reduce its function which are population specific. Detailed understanding and deeper knowledge of its role in the pathogenesis and prevention of many diseases is required. FUT2 may also have a potential role in the case of COVID-19 as a susceptible marker due to its association with respiratory diseases and the ABO blood group. There is an utmost need for this kind of review knowing its importance and owing to limited collective information.

Histo-Blood Group Antigens, Enteropathogen Carriage and Environmental Enteropathy in Stunted Zambian Children

OBJECTIVES

Stunting, the most common form of childhood undernutrition, is associated with environmental enteropathy (EE). Enteric infections are believed to play a role in the pathophysiology of EE and stunting though the exact mechanism remains undetermined. The FUT2 (secretor) and FUT3 (Lewis) genes have been shown to be associated with some symptomatic enteric infections in both children and adults. These genes are responsible for the presence of histo-blood group antigens (HBGAs) in various secretions and epithelial surfaces.We evaluated whether the secretor and Lewis status influences asymptomatic enteric infections and thus EE severity on duodenal biopsies of stunted children.

METHODS

In this case-control study, we used saliva samples to determine the secretor and Lewis status of stunted children (cases, n = 113) enrolled in a nutritional rehabilitation program and from their well-nourished counterparts (controls, n = 42). Where available, saliva was also collected from the mothers. Baseline stool samples were used to detect asymptomatic enteropathogen carriage. Duodenal biopsies were collected from a subgroup of stunted children (n = 77) who had an upper gastrointestinal endoscopy done as part of the evaluation process for their non-response to nutritional therapy.

RESULTS

The proportion of secretors was similar between the cases and the controls (82% vs 81%, P = 0.81). The stunted children had significantly higher rates of carrying multiple enteropathogens, but this was not associated with their secretor status nor that of their mothers. The secretor status was also not associated with mucosal morphometry of duodenal biopsies.

CONCLUSION

This case-control analysis in Zambian children does not support the hypothesis that fucosylation status determines asymptomatic enteropathogen carriage in stunting.

Effect of rotavirus genetic diversity on vaccine impact

Group A rotaviruses (RVAs) are the leading cause of gastroenteritis, causing 0.2 million deaths and several million hospitalisations globally each year. Four rotavirus vaccines (Rotarix^TM , RotaTeq^TM , Rotavac^® and ROTASIIL^® ) have been pre-qualified by the World Health Organization (WHO), but the two newly pre-qualified vaccines (Rotavac^® and ROTASIIL^® ) are currently only in use in Palestine and India, respectively. In 2009, WHO strongly proposed that rotavirus vaccines be included in the routine vaccination schedule of all countries around the world. By the end of 2019, a total of 108 countries had administered rotavirus vaccines, and 10 countries have currently been approved by Gavi for the introduction of rotavirus vaccine in the near future. With 39% of global coverage, rotavirus vaccines have had a substantial effect on diarrhoeal morbidity and mortality in different geographical areas, although efficacy appears to be higher in high income settings. Due to the segmented RNA genome, the pattern of RVA genotypes in the human population is evolving through interspecies transmission and/or reassortment events for which the vaccine might be less effective in the future. However, despite the relative increase in some particular genotypes after rotavirus vaccine use, the overall efficacy of rotavirus mass vaccination worldwide has not been affected. Some of the challenges to improve the effect of current rotavirus vaccines can be solved in the future by new rotavirus vaccines and by vaccines currently in progress.

The Role of Host Glycobiology and Gut Microbiota in Rotavirus and Norovirus Infection, an Update

Rotavirus (RV) and norovirus (NoV) are the leading causes of acute gastroenteritis (AGE) worldwide. Several studies have demonstrated that histo-blood group antigens (HBGAs) have a role in NoV and RV infections since their presence on the gut epithelial surfaces is essential for the susceptibility to many NoV and RV genotypes. Polymorphisms in genes that code for enzymes required for HBGAs synthesis lead to secretor or non-secretor and Lewis positive or Lewis negative individuals. While secretor individuals appear to be more susceptible to RV infections, regarding NoVs infections, there are too many discrepancies that prevent the ability to draw conclusions. A second factor that influences enteric viral infections is the gut microbiota of the host. In vitro and animal studies have determined that the gut microbiota limits, but in some cases enhances enteric viral infection. The ways that microbiota can enhance NoV or RV infection include virion stabilization and promotion of virus attachment to host cells, whereas experiments with microbiota-depleted and germ-free animals point to immunoregulation as the mechanism by which the microbiota restrict infection. Human trials with live, attenuated RV vaccines and analysis of the microbiota in responder and non-responder individuals also allowed the identification of bacterial taxa linked to vaccine efficacy. As more information is gained on the complex relationships that are established between the host (glycobiology and immune system), the gut microbiota and intestinal viruses, new avenues will open for the development of novel anti-NoV and anti-RV therapies.

Association of fucosyltransferase 2 gene with norovirus infection: A systematic review and meta-analysis

BACKGROUND

Norovirus is a leading cause of viral gastroenteritis outbreaks worldwide. Histo-blood group antigens (HBGAs) are important host attachment factors in susceptibility to norovirus. In this study, the association of FUT2 gene, which participates in the biosynthesis of HBGAs, with norovirus infection has been investigated.

METHODS

All relevant studies on the associations of FUT2 gene with norovirus were retrieved from PubMed, Web of Science, Embase, and Cochrane Library databases. Odds ratios (ORs) and 95% confidence interval (CI) were used to analyze the extracted data. I2 statistic, sensitivity analysis and publication bias analysis were used to confirm the findings. Subgroup analyses were performed for races, genotypes, development degree of the countries, publication years, age and setting when heterogeneity was recorded.

RESULTS

Twenty studies including 4066 participants were included for the meta-analysis. This analysis showed that there is a significant association between FUT2 gene and norovirus infection (OR = 3.02, 95%CI = 2.00-4.55, P < 0.001). Additionally, the ORs of norovirus infection among Chinese (OR = 4.49, 95%CI = 2.37-8.50, P < 0.001) were higher than those among Caucasian (OR = 3.23, 95%CI = 2.20-4.74, P < 0.001).

CONCLUSIONS

The meta-analysis suggested that FUT2 gene is associated with susceptibility to norovirus infection.

Plasma rotavirus-specific IgA and risk of rotavirus vaccine failure in infants in Malawi

BACKGROUND

Rotavirus vaccine efficacy is reduced in low-income populations, but efforts to improve vaccine performance are limited by lack of clear correlates of protection. While plasma rotavirus (RV)-specific IgA appears strongly associated with protection against rotavirus gastroenteritis in high-income countries, weaker association has been observed in low-income countries. We tested the hypothesis that lower RV-specific IgA is associated with rotavirus vaccine failure in Malawian infants.

METHODS

In a case-control study we recruited infants presenting with severe rotavirus gastroenteritis following monovalent oral rotavirus vaccination (RV1 vaccine failures). Conditional logistic regression was used to determine the odds of rotavirus seronegativity (RV-specific IgA<20 U/mL) in these cases compared 1:1 with age-matched, vaccinated, asymptomatic community controls. Plasma RV-specific IgA was determined by ELISA for all participants at recruitment, and for cases at 10 days post symptom onset. Rotavirus infection and genotype were determined by antigen testing and RT-PCR respectively.

RESULTS

In 116 age-matched pairs, infants with RV1 vaccine failure were more likely to be RV-specific IgA seronegative than controls: OR 3.1 (95%CI 1.6-5.9), p=0.001. In 60 infants with convalescent serology, 42/45 (93%, 95%CI 81-98%) infants seronegative at baseline became seropositive. Median rise in RV-specific IgA concentration following acute infection was 112.8 (IQR 19.1-380.6) fold.

CONCLUSIONS

In this vaccinated population with high residual burden of rotavirus disease, RV1 vaccine failure was associated with lower RV-specific IgA, providing further evidence of RV-specific IgA as a marker of protection. Robust convalescent RV-specific IgA response in vaccine failures suggests differences in wild-type and vaccine-induced immunity, which informs future vaccine development.

Dynamics of norovirus genotype change and early characterization of variants in children with diarrhea in central Tunisia, 2001-2012

Human noroviruses (HuNoVs), especially GII.4 strains, are a major cause of gastroenteritis epidemics in both children and adults. Stool samples were collected from 113 Tunisian children with acute gastroenteritis in 2001 and 2002 and were retrospectively tested for HuNoVs. Fifteen (13.2%) of the 113 samples were positive for HuNoVs, all of which were genogroup II strains, and the GII.4-2004/Hunter variant was predominant (67%). We reconstituted the temporal circulation of HuNoV strains in central Tunisia between 2003 and 2012 using HuNoV isolates reported in our previous studies. A comparative analysis showed a dynamic change in the molecular profile of the HuNoV strains over a 12-year period. We found that GII.4-2004/Hunter strains were circulating as early as June 2002 and that GIX.1[GII.P15] HuNoVs were already circulating four years before this genotype was first reported in Japan in 2006. Our data suggest that epidemic strains of HuNoV circulate for several years in the pediatric population before becoming predominant. This study suggests that children from low-income countries with poor sanitation may play a significant role in the molecular evolution of noroviruses and the global emergence of new epidemic strains.

Use of TaqMan Array Cards to investigate the aetiological agents of diarrhoea among young infants with severe acute malnutrition

OBJECTIVE

Studies involving less sensitive conventional microscopy and culture-based approaches have identified distinct differences in diarrhoeal aetiology in childhood malnutrition. Our study involved the use of an advanced molecular biology technique, the TaqMan Array Cards (TAC), to elucidate the diarrhoeal aetiology among young infants with severe acute malnutrition (SAM).

METHOD

A total of 113 faecal samples was collected from SAM infants, aged 2-6 months, upon admission to the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) with complications of diarrhoea and related comorbidities. We used TAC for the detection of 29 different diarrhoeal enteropathogens from a single faecal sample. For comparison, we also analysed 25 diarrhoeal samples from well-nourished infants of similar age.

RESULTS

Higher odds of detection of all bacterial enteropathogens were associated with diarrhoea among SAM infants. In particular, the detection of Aeromonas sp (aOR: 25.7, p = 0.011), Campylobacter sp (aOR: 9.6, p < 0.01) and ETEC (aOR: 5.2, p = 0.022) was significantly associated with diarrhoea among SAM infants in comparison to well-nourished infants. 80% higher odds of detection of rotavirus and norovirus GII were associated with diarrhoea among well-nourished infants in comparison to SAM infants (aOR: 0.2, p < 0.05).

CONCLUSION

Our study findings demonstrate a difference in diarrhoeal aetiology among SAM and well-nourished young infants, which may be useful in providing an evidence-based logic for possible revision of treatment guidelines for treatment of young diarrhoeal infants with SAM in the early management of the menace of antimicrobial resistance.

Maternal H-antigen secretor status is an early biomarker for potential preterm delivery

OBJECTIVE

Pre-pregnancy or first trimester biomarkers predicting preterm delivery are lacking. The purpose of this study was to determine whether maternal H-antigen (secretor status) is a potential biomarker for preterm delivery.

METHODS

This cohort study examined maternal saliva samples and birth data gathered by the National Children's Study Vanguard pilot phase (2009-2014) and included 300 women who were ≥18 years old and provided birth data and saliva samples. The maternal secretor status phenotype was determined by quantifying H-antigen in saliva using enzyme-linked immunoassay. Mothers were stratified by secretor status and multivariable analysis estimated adjusted associations with preterm delivery.

RESULTS

Maternal lack of H-antigen production was an independent risk factor for preterm delivery after adjusting for known confounders (aOR 4.53; 95% CI: 1.74, 11.81; P = 0.002).

CONCLUSIONS

Maternal H-antigen may be a biomarker identifying women at-risk for preterm delivery. Prospective cohort studies validating these findings are needed.

Secretor status strongly influences the incidence of symptomatic norovirus infection in a genotype-dependent manner in a Nicaraguan birth cohort

BACKGROUND

The role of histo-blood group on the burden and severity of norovirus gastroenteritis in young infants has not been well documented.

METHODS

Norovirus gastroenteritis was assessed in 443 Nicaraguan children followed from birth until 3 years of age. Stool samples were tested for norovirus by RT-qPCR and histo-blood group antigens (HBGA) were determined by phenotyping of saliva and blood. Hazards ratios (95% CI) and predictors of norovirus AGE outcome stratified by HBGA were estimated using Cox proportional hazards models.

RESULTS

Of 1,353 AGE episodes experienced by children, 229 (17%) tested positive for norovirus with an overall incidence of 21.9/100 child-years. Secretor children were infected as early as 2 months old and had a higher incidence of norovirus GII compared to non-secretor children (15.4 vs 4.1/100 child-years, P = 0.006). Furthermore, all GII.4 AGE episodes occurred in secretor children. Children infected with GI (adjusted OR=0.09, 95% CI 0.02-0.33) or non-GII.4 viruses (adjusted OR=0.2, 95% CI: 0.07-0.6) were less likely to have severe AGE compared to GII.4 infected children.

CONCLUSION

Secretor status in children strongly influences the incidence of symptomatic norovirus infection in a genogroup or genotype-dependent manner and provides evidence that clinical severity in children depends on norovirus genotypes.

Epidemiology of enteric virus infections in children living in the Amazon region

OBJECTIVES

To verify the frequency of viruses causing acute gastroenteritis (AGE) in association with the histo-blood group antigen (HBGA) and Rotarix™ vaccination coverage in children from the Amazon region.

DESIGN

Fecal and saliva samples were collected from children with AGE (n = 485) and acute respiratory infection (ARI) (n = 249) clinical symptoms. Rotavirus A (RVA), norovirus, human adenovirus (HAdV), and sapovirus (SaV) were verified in feces by molecular detection. Saliva samples were used for HBGA phenotyping/FUT3 genotyping. Blood group types, clinical aspects and Rotarix™ RVA vaccination data were recorded.

RESULTS

Norovirus remained the most prevalently detected cause of AGE (38%, 184/485 and ARI 21.3%, 53/249). High HAdV frequencies were observed in AGE children (28.6%, 139/485) and ARI children (37.3%, 93/249). RVA was the third most prevalent virus causing AGE (22.7%, 110/485 and ARI 19.3%, 48/249) and a low RV1 coverage (61%, 448/734) was verified. The SaV frequencies were lower (7.2%, 35/485 for AGE and 6.8%, 17/249 for ARI). Secretor children were HBGA susceptible to HAdV infection (OR 1.5, 95% CI 1.0-2.3; P = 0.04) but not to RVA, norovirus or SaV infection.

CONCLUSIONS

Norovirus could be considered the main etiological agent of AGE. No association was verified for HBGA susceptibility to RVA, norovirus and SaV. Secretor children showed a slight susceptibility to HAdV infection and the Le (a-b-) heterogeneous SNPs on the FUT3 gene.

The role of the blood group-related glycosyltransferases FUT2 and B4GALNT2 in susceptibility to infectious disease

The glycosylation profile of the gastrointestinal tract is an important factor mediating host-microbe interactions. Variation in these glycan structures is often mediated by blood group-related glycosyltransferases, and can lead to wide-ranging differences in susceptibility to both infectious- as well as chronic disease. In this review, we focus on the interplay between host glycosylation, the intestinal microbiota and susceptibility to gastrointestinal pathogens based on studies of two exemplary blood group-related glycosyltransferases that are conserved between mice and humans, namely FUT2 and B4GALNT2. We highlight that differences in susceptibility can arise due to both changes in direct interactions, such as bacterial adhesion, as well as indirect effects mediated by the intestinal microbiota. Although a large body of experimental work exists for direct interactions between host and pathogen, determining the more complex and variable mechanisms underlying three-way interactions involving the intestinal microbiota will be the subject of much-needed future research.

Virus Etiology, Diversity and Clinical Characteristics in South African Children Hospitalised with Gastroenteritis

BACKGROUND

Viral gastroenteritis remains a major cause of hospitalisation in young children. This study aimed to determine the distribution and diversity of enteric viruses in children ≤5 years, hospitalised with gastroenteritis at Kalafong Provincial Tertiary Hospital, Pretoria, South Africa, between July 2016 and December 2017.

METHODS

Stool specimens (n = 205) were screened for norovirus GI and GII, rotavirus, sapovirus, astrovirus and adenovirus by multiplex RT-PCR. HIV exposure and FUT2 secretor status were evaluated. Secretor status was determined by FUT2 genotyping.

RESULTS

At least one gastroenteritis virus was detected in 47% (96/205) of children. Rotavirus predominated (46/205), followed by norovirus (32/205), adenovirus (15/205), sapovirus (9/205) and astrovirus (3/205). Norovirus genotypes GI.3, GII.2, GII.3, GII.4, GII.7, GII.12, GII.21, and rotavirus strains G1P[8], G2P[4], G2P[6], G3P[4], G3P[8], G8P[4], G8P[6], G9P[6], G9P[8] and sapovirus genotypes GI.1, GI.2, GII.1, GII.4, GII.8 were detected; norovirus GII.4[P31] and rotavirus G3P[4] predominated. Asymptomatic norovirus infection (GI.3, GI.7, GII.4, GII.6, GII.13) was detected in 22% of 46 six-week follow up stools. HIV exposure (30%) was not associated with more frequent or severe viral gastroenteritis hospitalisations compared to unexposed children. Rotavirus preferentially infected secretor children (p = 0.143) and norovirus infected 78% secretors and 22% non-secretors.

CONCLUSION

Rotavirus was still the leading cause of gastroenteritis hospitalisations, but norovirus caused more severe symptoms.

Association between circulating rotavirus genotypes and histo-blood group antigens in the children hospitalized with acute gastroenteritis in Iran

Rotaviruses are the dominant cause of severe acute gastroenteritis in children under 5 years of age. Previous studies showed that some children are less susceptible to rotavirus gastroenteritis. It has been shown that this resistance depends on the rotavirus genotype and also human histo-blood group antigens (HBGAs), which works as a receptor for rotavirus surface protein (VP4). The present study aimed to evaluate the human genetic susceptibility to rotavirus gastroenteritis in Iran and to obtain a comparative analysis between rotavirus gastroenteritis and secretor or Lewis status in case and control groups in the Iranian population. The study was performed on fecal specimens from 108 children with acute rotavirus gastroenteritis from 2015 to 2017. A total of 50 fecal specimens from children with acute gastroenteritis of unknown etiology were also used as a control group. After the genotyping of positive rotavirus cases and human HBGAs by Sanger sequencing, the phylogenetic tree analysis showed that all rotavirus strains from Iran belonged to P[II]. The most common genotype was P[8] (n = 102; 94.4%), while the remaining belonged to P[4] (n = 3; 2.8%) and P[6] (n = 3; 2.8%) genotypes. The P[8] genotype was found to be associated with secretor and Lewis positive status (p < .05).

Understanding Pediatric Norovirus Epidemiology: A Decade of Study among Ghanaian Children

Understanding the epidemiology of human norovirus infection in children within Ghana and the entire sub-Saharan African region, where future norovirus vaccines would have the greatest impact, is essential. We analyzed 1337 diarrheic stool samples collected from children <5 years from January 2008 to December 2017 and found 485 (36.2%) shedding the virus. GII.4 (54.1%), GII.3 (7.7%), GII.6 (5.3%), GII.17 (4.7%), and GII.5 (4.7%) were the most common norovirus genotypes. Although norovirus GII.4 remained the predominant capsid genotype throughout the study period, an increase in GII.6 and GII.3 capsid genotypes was observed in 2013 and 2014, respectively. The severity of clinical illness in children infected with GII.4 norovirus strains was similar to illness caused by non-GII.4 strains. Since the epidemiology of norovirus changes rapidly, establishment of systematic surveillance within sentinel sites across the country would enhance the monitoring of circulating norovirus strains and allow continuous understanding of norovirus infection in Ghana.

Low fecal rotavirus vaccine virus shedding is significantly associated with non-secretor histo-blood group antigen phenotype among infants in northern Pretoria, South Africa

Histo-blood group antigens are recognized by rotaviruses in a P- genotype dependent manner and their frequency in a population can influence fecal virus shedding. This study investigated the rate of fecal shedding of Rotarix vaccine and its association with HBGA phenotype distribution in South Africa. Stool and saliva specimens were collected from 150 infants attending immunization on the day of both first and second doses and 7 days later. Virus shedding was detected by real-time qPCR while HBGA phenotypes in saliva were determined by enzyme linked immunosorbent assay. Vaccine virus shedding was higher (23.6%) after the first dose than the second dose (4.7%). About 77% of virus-shedding infants were secretors (OR = 129; 95% CI, 6.088 - 2733), compared with none of non-virus shedding infants. Non-secretor status was significantly associated with low vaccine virus shedding while the likelihood of shedding was significantly higher in secretors.

Norovirus-specific immunoglobulin A in breast milk for protection against norovirus-associated diarrhea among infants

BACKGROUND

Norovirus (NV) causes acute gastroenteritis in infants. Humoral and fecal immunoglobulin A (IgA) responses have been correlated with protection against NV; however, the role of breast milk IgA against NV infection and associated diarrhea is still unknown. This study aimed to evaluate the protective role of NV-specific IgA (NV-IgA) in breast milk.

METHODS

Ninety-five breast milk samples collected from mothers enrolled in a 2016-2017 Peruvian birth cohort study were tested for total IgA and NV-IgA by ELISA using GII·4 variants and non-GII·4 genotype virus-like particles (VLPs). Breast milk samples were grouped according to the NV infection and diarrheal status of infants: NV positive with diarrhea (NV+D+, n=18); NV positive without diarrhea (NV+D-, n=37); and NV negative without diarrhea (NV-D-, n=40). The percent positivity and titer of NV-IgA were compared among groups. The cross-reactivity was estimated based on the correlation of ratio between NV-IgA against GII·4 variants and non-GII·4 genotype VLPs.

FINDINGS

NV-IgA had high positivity rates against different VLPs, especially against GII (89-100%). The NV+D- group had higher percent positivity (89% vs. 61%, p=0·03) and median titer (1:100 vs 1:50, p=0·03) of NV-IgA than the NV+D+ group against GI·1 VLPs. A relatively high correlation between different GII·4 variants (0·87) and low correlation between genogroups (0·23-0·37) were observed.

INTERPRETATION

Mothers with high positivity rates and titers of NV-IgA in breast milk had NV infected infants with reduced diarrheal symptoms. Antigenic relatedness to the genetic diversity of human norovirus was suggested.Funding National Institute of Allergy and Infectious Diseases, National Institute of Health: 1R01AI108695-01A1 and the Japan Society for the Promotion of Science (Fostering Joint International Research B):19KK0241.

FUT2, Secretor Status and FUT3 Polymorphisms of Children with Acute Diarrhea Infected with Rotavirus and Norovirus in Brazil

Host susceptibility according to human histo-blood group antigens (HBGAs) is widely known for norovirus infection, but is less described for rotavirus. Due to the variable HBGA polymorphism among populations, we aimed to evaluate the association between HBGA phenotypes (ABH, Lewis and secretor status) and susceptibility to rotavirus and norovirus symptomatic infection, and the polymorphisms of FUT2 and FUT3, of children from southeastern Brazil. Paired fecal-buccal specimens from 272 children with acute diarrhea were used to determine rotavirus/norovirus genotypes and HBGAs phenotypes/genotypes, respectively. Altogether, 100 (36.8%) children were infected with rotavirus and norovirus. The rotavirus P[8] genotype predominates (85.7%). Most of the noroviruses (93.8%) belonged to genogroup II (GII). GII.4 Sydney represented 76% (35/46) amongst five other genotypes. Rotavirus and noroviruses infected predominantly children with secretor status (97% and 98.5%, respectively). However, fewer rotavirus-infected children were Lewis-negative (8.6%) than the norovirus-infected ones (18.5%). FUT3 single nucleotide polymorphisms (SNP) occurred mostly at the T59G > G508A > T202C > C314T positions. Our results reinforce the current knowledge that secretors are more susceptible to infection by both rotavirus and norovirus than non-secretors. The high rate for Lewis negative (17.1%) and the combination of SNPs, beyond the secretor status, may reflect the highly mixed population in Brazil.

Norovirus infection and HBGA host genetic susceptibility in a birth community-cohort, Rio de Janeiro, Brazil

Norovirus has emerged as an important viral agent of acute pediatric gastroenteritis, with a growing genetic diversity reported in the last decades. Histo-blood group antigens (HBGAs) present on the surface of enterocytes are susceptibility factors for norovirus infection and differ between populations which could affects the epidemiology and evolution of these viruses. This study investigated the frequency, incidence and genetic diversity of noroviruses in a cohort of rotavirus A vaccinated children in association to the host HBGA (Secretor/Lewis) genetic susceptibility profile. Norovirus genogroups I and II (GI/GII) were screened by RT-qPCR in 569 stool samples from 132 children followed-up from birth to 11 months of age during 2014--2018. Noroviruses were identified in 21.2% of children enrolled in this study, with a norovirus detection rate of 5.6% (32/569), in 17.1% and 4.7% of acute diarrheic episodes (ADE) and non-ADE, respectively. The norovirus incidence was 5.8 infections per 100 child-months. Partial nucleotide sequencing characterized six different norovirus genotypes, with GII.4 Sydney 2012 being detected in 50% associated with three different polymerase genotypes (GII·P31, GII·P16 and GII·P4 New Orleans 2009). FUT3 genotyping was yielded seven new mutations in this population. A significant association between symptomatic norovirus infection and secretor profile could be inferred.

Population-Level Human Secretor Status Is Associated With Genogroup 2 Type 4 Norovirus Predominance

BACKGROUND

Noroviruses are a leading cause of acute gastroenteritis. Genogroup 2 type 4 (GII.4) has been the dominant norovirus genotype worldwide since its emergence in the mid-1990s. Individuals with a functional fucosyltransferase-2 gene, known as secretors, have increased susceptibility to GII.4 noroviruses. We hypothesized that this individual-level trait may drive GII.4 norovirus predominance at the human population level.

METHODS

We conducted a systematic review for studies reporting norovirus outbreak or sporadic case genotypes and merged this with data on proportions of human secretor status in various countries from a separate systematic review. We used inverse variance-weighted linear regression to estimate magnitude of the population secretor-GII.4 proportion association.

RESULTS

Two hundred nineteen genotype and 112 secretor studies with data from 38 countries were included in the analysis. Study-level GII.4 proportion among all noroviruses ranged from 0% to 100%. Country secretor proportion ranged from 43.8% to 93.9%. We observed a 0.69% (95% confidence interval, 0.19-1.18) increase in GII.4 proportion for each percentage increase in human secretor proportion, controlling for Human Development Index.

CONCLUSIONS

Norovirus evolution and diversity may be driven by local population human host genetics. Our results may have vaccine development implications including whether specific antigenic formulations would be required for different populations.

Do Blood Group Antigens and the Red Cell Membrane Influence Human Immunodeficiency Virus Infection?

The expression of blood group antigens varies across human populations and geographical regions due to natural selection and the influence of environment factors and disease. The red cell membrane is host to numerous surface antigens which are able to influence susceptibility to disease, by acting as receptors for pathogens, or by influencing the immune response. Investigations have shown that Human Immunodeficiency Virus (HIV) can bind and gain entry into erythrocytes, and therefore it is hypothesized that blood groups could play a role in this process. The ABO blood group has been well studied. However, its role in HIV susceptibility remains controversial, while other blood group antigens, and the secretor status of individuals, have been implicated. The Duffy antigen is a chemokine receptor that is important in the inflammatory response. Those who lack this antigen, and type as Duffy null, could therefore be susceptible to HIV infection, especially if associated with neutropenia. Other antigens including those in the Rh, Lutheran and OK blood group systems have all been shown to interact with HIV. More recently, experiments show that cells which overexpress the P^k antigen appear to be protected against infection. These reports all demonstrate that red cell antigens interact and influence HIV infection. However, as the red cell membrane is complex and the pathogenesis of HIV multi-factorial, the role of blood group antigens cannot be studied in isolation.

Systematic sequence analysis of the FUT3 gene identifies 11 novel alleles in the Sindhi and Punjabi populations from Pakistan

The FUT3 (Lewis) gene is responsible for the expression of Lewis fucosyltransferase, which is required for the synthesis of the structural determinants of both Lewis^a and Lewis^b specificity. These factors play an important role not only in clinical but also in medico-legal investigations. The gene sequence is highly polymorphic and ethnically specific. In the current study, we performed systematic sequence analysis of the coding region of FUT3 by DNA sequencing to investigate the genetic variations of FUT3 and the molecular basis of the Lewis phenotype in the Sindhi and Punjabi populations of Pakistan. Twenty-three point mutations were observed, including 7 unreported mutations, among which two missense mutations (490 G > A and 959 T > C) were predicted to be deleterious to enzyme activity by software assessment. In total, we observed 24 Lewis alleles, including 11 novel ones. However, all unreported missense mutations were present in Lewis-negative alleles confirmed previously. According to genotypic data, the Lewis-negative phenotypic frequencies were 11.5% and 22.93% in the Sindhi and Punjabi ethnic groups, respectively. Moreover, we found that le^202,314 and le^59,1067 were predominant among Lewis-negative alleles, while the frequency of le^59,1067 in the Punjabi population was significantly higher than that in the Sindhi population. In summary, our study revealed that there is a relatively high degree of sequence variation of the Lewis gene in Pakistani populations and provided the first genetic data on FUT3 in these two ethnic groups from Pakistan. The allele types and their frequencies showed that these ethnic groups exhibit more Caucasian components.

Human Neonatal Rotavirus Vaccine (RV3-BB) Produces Vaccine Take Irrespective of Histo-Blood Group Antigen Status

BACKGROUND

VP4 [P] genotype binding specificities of rotaviruses and differential expression of histo-blood group antigens (HBGAs) between populations may contribute to reduced efficacy against severe rotavirus disease. P[6]-based rotavirus vaccines could broaden protection in such settings, particularly in Africa, where the Lewis-negative phenotype and P[6] rotavirus strains are common.

METHODS

The association between HBGA status and G3P[6] rotavirus vaccine (RV3-BB) take was investigated in a phase 2A study of RV3-BB vaccine involving 46 individuals in Dunedin, New Zealand, during 2012-2014. FUT2 and FUT3 genotypes were determined from DNA extracted from stool specimens, and frequencies of positive cumulative vaccine take, defined as an RV3-BB serum immune response (either immunoglobulin A or serum neutralizing antibody) and/or stool excretion of the vaccine strain, stratified by HBGA status were determined.

RESULTS

RV3-BB produced positive cumulative vaccine take in 29 of 32 individuals (91%) who expressed a functional FUT2 enzyme (the secretor group), 13 of 13 (100%) who were FUT2 null (the nonsecretor group), and 1 of 1 with reduced FUT2 activity (i.e., a weak secretor); in 37 of 40 individuals (93%) who expressed a functional FUT3 enzyme (the Lewis-positive group) and 3 of 3 who were FUT3 null (the Lewis-negative group); and in 25 of 28 Lewis-positive secretors (89%), 12 of 12 Lewis-positive nonsecretors (100%), 2 of 2 Lewis-negative secretors, and 1 of 1 Lewis-negative weak secretor.

CONCLUSIONS

RV3-BB produced positive cumulative vaccine take irrespective of HBGA status. RV3-BB has the potential to provide an improved level of protection in settings where P[6] rotavirus disease is endemic, irrespective of the HBGA profile of the population.

ABO blood group-associated susceptibility to norovirus infection: A systematic review and meta-analysis

BACKGROUND

Norovirus is responsible for the viral gastroenteritis burden worldwide. Histo-blood type antigens (HBGAs) are the only well-known factor regarding their effect on the pathogenesis of norovirus. Here, we performed the study to further investigate the association of the ABO blood group with norovirus susceptibility.

METHODS

All relevant studies were retrieved from PubMed, Embase, Web of Science, and Cochrane Library databases and the associations of ABO blood groups with norovirus were assessed. The pooled odds ratios (ORs) and 95% confidence interval (CI) were calculated from extracted data. I² statistics, sensitivity analysis, and publication bias were used to confirm the findings. Subgroup analyses were performed for genotypes, publication years, development degree of the countries, and age if heterogeneity was recorded.

RESULTS

Seventeen articles covering 2304 participants were included. The overall analysis of the studies showed similar ORs of norovirus infection among individuals with blood type A (OR = 0.90, 95%CI = 0.71-1.14, P = 0.37) and blood type B (OR = 0.85, 95%CI = 0.66-1.12, P = 0.25) as compared to those controls. An increased odds of norovirus infection was found among individuals with blood type O (OR = 1.28, 95%CI = 1.03-1.59, P = 0.03), while the individuals with blood type AB (OR = 0.91, 95%CI = 0.60-1.39, P = 0.67) showed no correlation with norovirus infection. For blood type B and blood type AB, the results of subgroup analyses mirrored the observations above.

CONCLUSIONS

The meta-analysis suggested that the blood type A, B and AB might not affect susceptibility to norovirus infection. However, blood type O appeared to be more susceptible to norovirus infection.

Nonsecretor Histo-blood Group Antigen Phenotype Is Associated With Reduced Risk of Clinical Rotavirus Vaccine Failure in Malawian Infants

BACKGROUND

Histo-blood group antigen (HBGA) Lewis/secretor phenotypes predict genotype-specific susceptibility to rotavirus gastroenteritis (RVGE). We tested the hypothesis that nonsecretor/Lewis-negative phenotype leads to reduced vaccine take and lower clinical protection following vaccination with G1P[8] rotavirus vaccine (RV1) in Malawian infants.

METHODS

A cohort study recruited infants receiving RV1 at age 6 and 10 weeks. HBGA phenotype was determined by salivary enzyme-linked immunosorbent assay (ELISA). RV1 vaccine virus shedding was detected by quantitative real-time polymerase chain reaction (qRT-PCR) in stool collected on alternate days for 10 days post-immunization. Plasma rotavirus-specific immunoglobulin A was determined by ELISA pre- and post-immunization. In a case-control study, HBGA phenotype distribution was compared between RV1-vaccinated infants with RVGE and 1:1 age-matched community controls. Rotavirus genotype was determined by RT-PCR.

RESULTS

In 202 cohort participants, neither overall vaccine virus fecal shedding nor seroconversion differed by HBGA phenotype. In 238 case-control infants, nonsecretor phenotype was less common in infants with clinical vaccine failure (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.20-0.75). Nonsecretor phenotype was less common in infants with P[8] RVGE (OR, 0.12; 95% CI, 0.03-0.50) and P[4] RVGE (OR, 0.17; 95% CI, 0.04-0.75). Lewis-negative phenotype was more common in infants with P[6] RVGE (OR, 3.2; 95% CI, 1.4-7.2).

CONCLUSIONS

Nonsecretor phenotype was associated with reduced risk of rotavirus vaccine failure. There was no significant association between HBGA phenotype and vaccine take. These data refute the hypothesis that high prevalence of nonsecretor/Lewis-negative phenotypes contributes to lower rotavirus vaccine effectiveness in Malawi.

Molecular characterization of norovirus infection responsible for acute diarrhea in Congolese hospitalized children under five years old in Brazzaville, Republic of Congo

BACKGROUND

Acute diarrhea is a leading cause of morbidity and mortality among children under five worldwide. As no published data is available on the occurrence of this infection in the Republic of Congo, this study aimed at (1) determining the prevalence and (2) characterizing genotypes of norovirus strains in Brazzaville.

METHODS

From June 2012 to June 2013, stool samples were collected from hospitalized young children with acute gastroenteritis. A total of 545 samples were tested for GI and GII norovirus infections using nested duplex reverse-transcription-polymerase chain reaction and sequencing.

RESULTS

The GI and GII norovirus infection were detected in 148 samples. Males (28%) were not significantly more infected than females (25%). Norovirus infection was found exclusively in children aged under 24 months with a higher prevalence (P=0,048) in the age group of 7-12 months, and throughout the year with a peak in August and September. Genetic diversity of norovirus strains revealed that GII was the most prevalent (87%). No risk factor was significantly associated with norovirus infection.

CONCLUSION

This study showed that noroviruses are important agents responsible for acute diarrhea in Congolese children and highlights the importance of continued surveillance.

Histo-Blood Group Antigens in Children with Symptomatic Rotavirus Infection

Group A rotaviruses are a major cause of acute gastroenteritis in children. The diversity and unequal geographical prevalence of rotavirus genotypes have been linked to histo-blood group antigens (HBGAs) in different human populations. In order to evaluate the role of HBGAs in rotavirus infections in our population, secretor status (FUT2+), ABO blood group, and Lewis antigens were determined in children attended for rotavirus gastroenteritis in Valencia, Spain. During three consecutive years (2013-2015), stool and saliva samples were collected from 133 children with rotavirus infection. Infecting viral genotypes and HBGAs were determined in patients and compared to a control group and data from blood donors. Rotavirus G9P[8] was the most prevalent strain (49.6%), followed by G1P[8] (20.3%) and G12P[8] (14.3%). Rotavirus infected predominantly secretor (99%) and Lewis b positive (91.7%) children. Children with blood group A and AB were significantly more prone to rotavirus gastroenteritis than those with blood group O. Our results confirm that a HBGA genetic background is linked to rotavirus P[8] susceptibility. Rotavirus P[8] symptomatic infection is manifestly more frequent in secretor-positive (FUT2+) than in non-secretor individuals, although no differences between rotavirus G genotypes were found.

Norovirus Infections and Disease in Lower-MiddleandLow-Income Countries, 1997⁻2018

Noroviruses are a major cause of viral gastroenteritis. The burden of the norovirus in low-resource settings is not well-established due to limited data. This study reviews the norovirus prevalence, epidemiology, and genotype diversity in lower-middle-income countries (LMIC) and in low-income countries (LIC). PubMed was searched up to 14 January 2019 for norovirus studies from all LIC and LMIC (World Bank Classification). Studies that tested gastroenteritis cases and/or asymptomatic controls for norovirus by reverse transcription-polymerase chain reaction (RT-PCR) were included. Sixty-four studies, the majority on children <5 years of age, were identified, and 14% (95% confidence interval; CI 14–15, 5158/36,288) of the gastroenteritis patients and 8% (95% CI 7–9, 423/5310) of healthy controls tested positive for norovirus. In LMIC, norovirus was detected in 15% (95% CI 15–16) of cases and 8% (95% CI 8–10) of healthy controls. In LIC, 11% (95% CI 10–12) of symptomatic cases and 9% (95% CI 8–10) of asymptomatic controls were norovirus positive. Norovirus genogroup II predominated overall. GII.4 was the predominant genotype in all settings, followed by GII.3 and GII.6. The most prevalent GI strain was GI.3. Norovirus causes a significant amount of gastroenteritis in low-resource countries, albeit with high levels of asymptomatic infection in LIC and a high prevalence of coinfections.

Genetic Susceptibility to Human Norovirus Infection: An Update

Noroviruses are the most common etiological agent of acute gastroenteritis worldwide. Despite their high infectivity, a subpopulation of individuals is resistant to infection and disease. This susceptibility is norovirus genotype-dependent and is largely mediated by the presence or absence of human histo-blood group antigens (HBGAs) on gut epithelial surfaces. The synthesis of these HBGAs is mediated by fucosyl- and glycosyltransferases under the genetic control of the FUT2 (secretor), FUT3 (Lewis) and ABO(H) genes. The so-called non-secretors, having an inactivated FUT2 enzyme, do not express blood group antigens and are resistant to several norovirus genotypes, including the predominant GII.4. Significant genotypic and phenotypic diversity of HBGA expression exists between different human populations. Here, we review previous in vivo studies on genetic susceptibility to norovirus infection. These are discussed in relation to population susceptibility, vaccines, norovirus epidemiology and the impact on public health.

Molecular epidemiology and host genetics of norovirus and rotavirus infections in Portuguese elderly living in aged care homes

Norovirus (NoV) and rotavirus group A (RVA) are major agents of acute gastroenteritis worldwide. This study aimed to investigate their epidemiological profile in Portuguese elderly living in long-term care facilities and to assess the host genetic factors mediating infection susceptibility. From November 2013 to June 2015, 636 faecal specimens from 169 elderly, mainly asymptomatic, living in nursing homes in Greater Lisbon and Faro district, Portugal, were collected. NoV and RVA were detected by real-time polymerase chain reaction and NoV genotyped by phylogenetic analysis. NoV detection rate was 7.1% (12 of 169). Three GI.3 and one GII.6 strains were genotyped. RVA detection rate was 3.6% (6 of 169), exclusively in asymptomatic individuals. Host genetic factors associated with infection susceptibility were described on 250 samples by saliva-based enzyme-linked immunosorbent assays. The Lewis-negative phenotype was 8.8% (22 of 250) and the rate of nonsecretors was 16.8% (42 of 250). Association to NoV and RVA infection was performed in the subgroup of individuals (n = 147) who delivered both faecal and saliva samples. The majority of NoV- and RVA-positive individuals (90.9% and 83.3%, respectively) were secretor-positive, with Lewis B phenotype. In a subset of individuals, FUT2 and FUT3 genes were genotyped to assess mutations and validate the secretor and Lewis phenotypes. All sequenced nonsecretors were homozygous for FUT2 nonsense mutation G428A. In this study, low detection rates of NoV and RVA infections were found during two winter seasons. However, even in the absence of any outbreak, the importance of finding these infections in a nonepidemic situation in long-term care facilities may have important implications for infection control.

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

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

Viral gastroenteritis among children of 0-5 years in Nigeria: Characterization of the first Nigerian aichivirus, recombinant noroviruses and detection of a zoonotic astrovirus

BACKGROUND

Viruses are the leading cause of acute gastroenteritis in children worldwide. Understanding of the occurrence and genetic diversity of these viruses can help to prevent infections.

OBJECTIVES

The present study describes the presence, genetic diversity and possible recombination of five enteric viruses in children with gastroenteritis in Southwestern Nigeria.

STUDY DESIGN

From August 2012 to December 2013, stool samples and sociodemographic data of 103 diarrheic children <5 years were collected to detect and characterize rotavirus A, norovirus, human astrovirus, aichivirus and sapovirus using PCR techniques followed by sequencing and phylogenetic analyses.

RESULTS

At least one virus was identified in 58.3% (60/103) of the stool samples. Rotavirus, norovirus and astrovirus were detected in 39.8% (41/103), 10.7% (11/103), and 6.8% (7/103) respectively. Notably, aichivirus was detected for the first time in Nigeria (1/103; 0.97%). Sapovirus was not detected in the study. Co-infections with rotavirus were observed in eight samples either with norovirus or astrovirus or aichivirus. Phylogenetic analyses of different genome regions of norovirus positive samples provided indication for recombinant norovirus strains. A novel astrovirus strain closely related to canine astrovirus was identified and further characterized for the first time.

CONCLUSIONS

Viruses are the common cause of acute gastroenteritis in Nigerian infants with rotavirus as most frequently detected pathogen. New norovirus recombinants and a not yet detected zoonotic astrovirus were circulating in Southwestern Nigeria, providing new information about emerging and unusual strains of viruses causing diarrhea.

FUT2 Secretor Status Is Not Associated With Oral Poliovirus Vaccine Immunogenicity in South Indian Infants

FUT2 determines whether histo-blood group antigens are secreted at mucosal surfaces. Secretor status influences susceptibility to enteric viruses, potentially including oral poliovirus vaccine (OPV). We performed a nested case-control study to determine the association between FUT2 genotype (single-nucleotide polymorphisms G428A, C302T, and A385T) and seroconversion among Indian infants who received a single dose of monovalent type 3 OPV. Secretor prevalence was 75% (89 of 118) in infants who seroconverted and 80% (97 of 122) in infants who did not seroconvert (odds ratio, 0.79; 95% confidence interval, .43-1.45). Our findings suggest that FUT2 genotype is not a key determinant of variation in OPV immunogenicity.