Assessment of the aetiology of acute gastroenteritis outbreaks in infants reveals rotavirus, noroviruses and adenovirus prevalence and viral coinfections in Nsukka, Nigeria

A better understanding of the aetiology of acute gastroenteritis (AGE) outbreaks in Southeast Nigeria would help safeguarding public health. This study screened stool samples collected from infants (children < 5 years of age) attending selected hospitals in Nsukka for human enteric viruses and evaluated the seasonality of AGE based on three-year records available at selected hospitals. A total of 120 stool samples (109 from diarrhoeal-patients and 11 from non-diarrhoeal patients, as control) collected during the AGE outbreaks of January - March 2019 and January-February 2020. The samples were analysed using an immunochromatographic lateral flow assay for differential qualitative detection of rotavirus (RoV), adenovirus (AdV), and norovirus genogroups I and II (NoVI, NoVII). Three-year (2017-2019) retrospective data on the cases of AGE reported at the hospitals were also collected and analysed. The overall prevalence of acute gastroenteritis was high (75.83%), with 13.19%representing viral co-infections. Rotavirus detection rate (69.17%) was higher than that for other viral agents (15.83%). Both mono- and mixed infections were observed for RoV, AdV and NoVII, whereas NoVI was detected only in co-infection cases. Analysis of risk factors showed that acute gastroenteritis was detected more often in infants of age ˂1 year (73.53%) than in those 1 ≤ 2 years (22.55%) or > 2 years (3.92%) in age. Gender and age were not associated with the cases of co-infections (p˂0.05). The seasonality data indicated one peak of the infection occurring in January 2017 which has decreased consecutively in the subsequent two years. These results demonstrate the prevalence and co-occurrence of enteric viruses in cases of infantile diarrhoea in Nsukka. Further molecular characterization of enteric virus strains, especially noroviruses, in this region would contribute significantly to global epidemiological data.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-023-00821-2.

Rotavirus A Inoculation and Oral Vitamin A Supplementation of Vitamin A Deficient Pregnant Sows Enhances Maternal Adaptive Immunity and Passive Protection of Piglets against Virulent Rotavirus A

The aim of this study was to determine the impact of vitamin A deficiency (VAD)/supplementation (±VA) and group A RV (RVA) maternal immunization of RVA seropositive multiparous pregnant sows, on their immune responses (anamnestic response) and on passive protection of their piglets against RVA challenge. Our results showed that VAD- mock sows had increased RVA RNA shedding at 1-5 days post piglet RVA challenge, and their litters had increased RVA shedding and diarrhea frequency throughout the experiment. VAD decreased memory B cell frequencies while VA supplementation increased RVA specific IgA/IgG antibody (Ab) secreting cell (ASC) numbers in blood, milk, and tissues of RVA inoculated VAD sows. The increased numbers of RVA specific IgA/IgG ASCs in blood, milk/colostrum, intestinal contents, and tissues in VA supplemented VAD sows, suggest a role of VA in B cell immunity and trafficking to tissues. We also observed that RVA inoculated sows had the highest viral neutralizing Ab titers in serum and milk while VA supplementation of VAD sows and RVA inoculation increased IgA⁺ B cell frequencies in sow colostrum. In summary, we demonstrated that daily oral VA-supplementation (2nd trimester-throughout lactation) to RVA inoculated VAD sows improved the function of their gut-mammary-IgA immunological axis, reducing viral RNA shedding, diarrhea, and increasing weight gain in suckling piglets.

Rotaviruses A and C in dairy cattle in the state of Rio de Janeiro, Brazil

Stool samples were collected from calves from nine family-based small dairy farms in the state of Rio de Janeiro, for detection and characterization of rotavirus (RV) species A, B, and C (RVA, RVB, and RVC, respectively) by reverse transcription polymerase chain reaction. Twenty-six samples (27.7%) were positive for at least one of the species: 22 (23.4%) samples were positive only for RVA, 3 (3.2%) were positive for RVC, and one sample (1.1%) had co-infection of RVA and RVC. RVB was not detected. Seven (21.9%; n = 32) animals with diarrhea and 19 (30.1% n = 62) asymptomatic animals were positive, with no significant difference in positivity (p = 0.3677). RV was detected in all properties studied, at rates between 14.3 and 80%, demonstrating the widespread circulation of RV in four of the seven geographic regions of the state of Rio de Janeiro. Infection was more prevalent among animals ≤ 6 months of age. Sequence analysis of a portion of the RVA VP6-encoding gene identified the I2 genotype. RVC was also detected; to our knowledge, this is the first description of this agent in cattle in Brazil. The data presented here should add knowledge regarding the importance and prevalence of RV in our national territory, and may facilitate the planning and implementation of control and prevention measures for bovine rotavirus infections in Brazil.

Rotavirus research: 2014-2020

Rotaviruses are major causes of acute gastroenteritis in infants and young children worldwide and also cause disease in the young of many other mammalian and of avian species. During the recent 5-6 years rotavirus research has benefitted in a major way from the establishment of plasmid only-based reverse genetics systems, the creation of human and other mammalian intestinal enteroids, and from the wide application of structural biology (cryo-electron microscopy, cryo-EM tomography) and complementary biophysical approaches. All of these have permitted to gain new insights into structure-function relationships of rotaviruses and their interactions with the host. This review follows different stages of the viral replication cycle and summarizes highlights of structure-function studies of rotavirus-encoded proteins (both structural and non-structural), molecular mechanisms of viral replication including involvement of cellular proteins and lipids, the spectrum of viral genomic and antigenic diversity, progress in understanding of innate and acquired immune responses, and further developments of prevention of rotavirus-associated disease.

Levels of human Rotaviruses and Noroviruses GII in urban rivers running through the city mirror their infection prevalence in populations

Enteric viruses exposed to water pose a huge threat to global public health and can lead to waterborne disease outbreaks. A sudden increase in enteric viruses in some water matrices also underpins the prevalence of corresponding waterborne diseases in communities over the same time period. However, few efforts have been focused on water matrices whose viral pollution may best reflect the clinical prevalence in communities. Here, a one-year surveillance of human enteric viruses including Enteroviruses (EnVs), Rotaviruses (HRVs), Astroviruses (AstVs), Noroviruses GII (HuNoVsGII) and Mastadenoviruses (HAdVs) in four representative water matrices: an urban river (UR) running through city, effluent from Wastewater Treatment Plant (EW), raw water for Urban Water Treatment Plant (RW), and tap water (TW) were performed by qPCR. The relationship between the virus detection frequency at each site and their prevalence in clinical PCR assay was further analyzed. We found that the detection frequencies of HRVs, HuNoVsGII, and AstVs in stools peaked in winter, while EnVs peaked in autumn. No EnVs occurred in EW, RW, or TW, but HuNoVsGII and AstVs occurred intensively in winter. For UR, all types of enteric viruses could be detected and the levels of acute gastroenteritis viruses (HRVs, HuNoVsGII, AstVs, and HAdVs) were highest in autumn or winter, whereas EnVs peaked in summer. In terms of correlation analyses, only HRVs and HuNoVsGII levels in UR showed a strong positive correlation with their prevalence in clinical stool samples. This study indicated that HRVs and HuNoVsGII levels in URs may mirror the local virus prevalence, thereby implying the possibility of revealing their local epidemiology by monitoring them in the URs.

Epidemiology and genotypes of group A rotaviruses in cattle and goats of Bangladesh, 2009-2010

Group A rotavirus (RVA) is recognized as a major cause of severe gastroenteritis in newborn calves and goat kids. We estimated the proportion of ruminants infected with rotavirus and identified the circulating genotypes in cattle and goats in Bangladesh. Between May 2009 and August 2010, fecal samples were collected from 520 cattle and goats presenting with diarrhea at three government veterinary hospitals in three districts of Bangladesh. All samples were screened for RVA RNA using real-time, one-step, reverse transcription polymerase chain reaction (qRT-PCR). Of the 520 animals tested, 11.7% (61) were positive for RVA RNA, with 6.2% (15/241) and 16.5% (46/279) positivity in cattle and goats, respectively. RVA positive samples were further characterized by nucleotide sequence analysis of two structural protein gene fragments, VP7 (G genotype), and VP4 (P genotype). Among 17 successfully sequenced strains, G8 (17.9%) was the most prevalent G-genotype followed by G10 (8%) and G6 (1.6%). P[1] (11.3%) was the most frequently detected P-genotype followed by P[11] (3.2%) and P[15] (1.6%). The most common VP7/VP4 combinations for cattle were G10P[11], G10P[15], and G6P[11], and for goat, G8P[1], and G10P[1]. Phylogenetic analysis of the RVA strains showed clustering with bovine and caprine strains from neighboring India. The study adds to our understanding of the genetic diversity of bovine and caprine rotavirus strains in Bangladesh. Our findings highlight the importance of rotavirus surveillance in cattle and goat populations, which may serve as a potential source for genetic reassortment and zoonotic transmission.

Whole-genome sequencing and analyses identify high genetic heterogeneity, diversity and endemicity of rotavirus genotype P[6] strains circulating in Africa

Rotavirus A (RVA) exhibits a wide genotype diversity globally. Little is known about the genetic composition of genotype P[6] from Africa. This study investigated possible evolutionary mechanisms leading to genetic diversity of genotype P[6] VP4 sequences. Phylogenetic analyses on 167 P[6] VP4 full-length sequences were conducted, which included six porcine-origin sequences. Of the 167 sequences, 57 were newly acquired through whole genome sequencing as part of this study. The other 110 sequences were all publicly-available global P[6] VP4 full-length sequences downloaded from GenBank. The strength of association between the phenotypic features and the phylogeny was also determined. A number of reassortment and mixed infections of RVA genotype P[6] strains were observed in this study. Phylogenetic analyses demostrated the extensive genetic diversity that exists among human P[6] strains, porcine-like strains, their concomitant clades/subclades and estimated that P[6] VP4 gene has a higher substitution rate with the mean of 1.05E-3 substitutions/site/year. Further, the phylogenetic analyses indicated that genotype P[6] strains were endemic in Africa, characterised by an extensive genetic diversity and long-time local evolution of the viruses. This was also supported by phylogeographic clustering and G-genotype clustering of the P[6] strains when Bayesian Tip-association Significance testing (BaTS) was applied, clearly supporting that the viruses evolved locally in Africa instead of spatial mixing among different regions. Overall, the results demonstrated that multiple mechanisms such as reassortment events, various mutations and possibly interspecies transmission account for the enormous diversity of genotype P[6] strains in Africa. These findings highlight the need for continued global surveillance of rotavirus diversity.

Changes of haemogram and serum biochemistry in neonatal piglet diarrhoea associated with porcine rotavirus type A

Porcine rotavirus type A (RVA) is a major cause of neonatal piglet mortality in India. The effect of the disease on haemogram and serum biochemical profile is not well established in piglets. Accordingly, we assessed the haemogram and serum biochemical profile in the neonatal piglet diarrhoea with RVA infection (n = 17). The diagnosis of RVA was confirmed using RNA-polyacrylamide gel electrophoresis (RNA-PAGE), commercially available enzyme-linked immunosorbent assay (ELISA) kit and reverse transcription-polymerase chain reaction (RT-PCR). Non-infected healthy piglets (n = 6) served as control. The concentrations of total protein, albumin, alanine amino transaminase (ALT), aspartate amino transaminase (AST), blood urea nitrogen (BUN) and creatinine in serum were measured by spectrophotometric method. Haemogram was done in the blood using sodium ethylenediaminetetraacetic acid (Na₂ EDTA) as anticoagulant. The mean values of total protein, albumin and globulin concentrations were significantly (P < 0.001) decreased and concentrations of ALT, AST, BUN and creatinine were significantly increased (P < 0.001) in the RVA-infected piglets. Haemogram showed marked haemoconcentration (P < 0.001), leukopenia (P < 0.01) and neutropenia (P < 0.01) in the presence of RVA infection than healthy piglets. The results indicated a possible extra-intestinal spread of RVA in piglets during neonatal diarrhoea. The finding might be helpful to clinicians and while treating such type of clinical cases, incorporation of organ protective drugs will be helpful for better response in the treatment schedule.

Comparative analysis of the Rotarix™ vaccine strain and G1P[8] rotaviruses detected before and after vaccine introduction in Belgium

G1P[8] rotaviruses are responsible for the majority of human rotavirus infections worldwide. The effect of universal mass vaccination with rotavirus vaccines on circulating G1P[8] rotaviruses is still poorly understood. Therefore we analyzed the complete genomes of the Rotarix™ vaccine strain, and 70 G1P[8] rotaviruses, detected between 1999 and 2010 in Belgium (36 before and 34 after vaccine introduction) to investigate the impact of rotavirus vaccine introduction on circulating G1P[8] strains. All rotaviruses possessed a complete Wa-like genotype constellation, but frequent intra-genogroup reassortments were observed as well as multiple different cluster constellations circulating in a single season. In addition, identical cluster constellations were found to circulate persistently over multiple seasons. The Rotarix™ vaccine strain possessed a unique cluster constellation that was not present in currently circulating G1P[8] strains. At the nucleotide level, the VP6, VP2 and NSP2 gene segments of Rotarix™ were relatively distantly related to any Belgian G1P[8] strain, but other gene segments of Rotarix™ were found in clusters also containing circulating Belgian strains. At the amino acid level, the genetic distance between Rotarix™ and circulating Belgian strains was considerably lower, except for NSP1. When we compared the Belgian G1P[8] strains collected before and after vaccine introduction a reduction in the proportion of strains that were found in the same cluster as the Rotarix™ vaccine strain was observed for most gene segments. The reduction in the proportion of strains belonging to the same cluster may be the result of the vaccine introduction, although natural fluctuations cannot be ruled out.

Inflammatory and oxidative stress in rotavirus infection

Rotaviruses are the single leading cause of life-threatening diarrhea affecting children under 5 years of age. Rotavirus entry into the host cell seems to occur by sequential interactions between virion proteins and various cell surface molecules. The entry mechanisms seem to involve the contribution of cellular molecules having binding, chaperoning and oxido-reducing activities. It appears to be that the receptor usage and tropism of rotaviruses is determined by the species, cell line and rotavirus strain. Rotaviruses have evolved functions which can antagonize the host innate immune response, whereas are able to induce endoplasmic reticulum (ER) stress, oxidative stress and inflammatory signaling. A networking between ER stress, inflammation and oxidative stress is suggested, in which release of calcium from the ER increases the generation of mitochondrial reactive oxygen species (ROS) leading to toxic accumulation of ROS within ER and mitochondria. Sustained ER stress potentially stimulates inflammatory response through unfolded protein response pathways. However, the detailed characterization of the molecular mechanisms underpinning these rotavirus-induced stressful conditions is still lacking. The signaling events triggered by host recognition of virus-associated molecular patterns offers an opportunity for the development of novel therapeutic strategies aimed at interfering with rotavirus infection. The use of N-acetylcysteine, non-steroidal anti-inflammatory drugs and PPARγ agonists to inhibit rotavirus infection opens a new way for treating the rotavirus-induced diarrhea and complementing vaccines.

Genetic diversity of rotavirus genome segment 6 (encoding VP6) in Pretoria, South Africa

BACKGROUND

Rotavirus viral protein 6 (VP6), encoded by genome segment (GS) 6, is the primary target for rotavirus diagnosis by serological and some molecular techniques. Selected full length nucleotide sequences of GS 6 of rotavirus strains from South Africa were sequenced and analysed to determine genetic diversity and variations within the circulating rotaviruses.

FINDINGS

The VP6 amplicons were sequenced using the Sanger ABI 3130xl. Phylogenetic and pairwise analysis revealed that the VP6 genes of the study strains belonged to two different VP6 [I] genotypes. Five sequences were assigned genotype I1 and seven as genotype I2. Comparison of the group specific antigenic regions of the South African strains to the reference strains, shows that the South African VP6 sequences belonging to the VP6 genotype I2 were highly conserved, with only two amino acids changes at positions 239 (T›N) and 261(I›V). On the other hand, South African VP6 sequences belonging to I1 genotypes revealed several amino acid variations mostly within the antigenic region III.

CONCLUSIONS

Rotavirus strains with I1 and I2 genotype are predominantly circulating within the South African communities of which the later seems to be more conserved within the antigenic regions. The observed genetic variations observed within GS 6 of rotaviruses analysed in the current study are unlikely to impact negatively on the performance of the current VP6-based detection methods. Nevertheless, investigators should continually consider this diversity and adapt the primer design for the detection and characterization of the VP6 gene accordingly.

The prevalence and genetic diversity of group A rotaviruses on pig farms in the Mekong Delta region of Vietnam

Group A rotaviruses (ARoVs) are a common cause of severe diarrhea among children worldwide and the cause of approximately 45% of pediatric hospitalizations for acute diarrhea in Vietnam. ARoVs are known to cause significant economic losses to livestock producers by reducing growth performance and production efficiencies, however little is known about the implications of asymptomatic endemic circulation of ARoV. We aimed to determine the prevalence and predominant circulating genotypes of ARoVs on pig farms in a southern province of Vietnam. We found overall animal-level and farm-level prevalence of 32.7% (239/730) and 74% (77/104), respectively, and identified six different G types and 4 P types in various combinations (G2, G3, G4, G5, G9, G11 and P[6], P[13], P[23], and P[34]). There was no significant association between ARoV infection and clinical disease in pigs, suggesting that endemic asymptomatic circulation of ARoV may complicate rotavirus disease attribution during outbreaks of diarrhea in swine. Sequence analysis of the detected ARoVs suggested homology to recent human clinical cases and extensive genetic diversity. The epidemiological relevance of these findings for veterinary practitioners and to ongoing pediatric ARoV vaccine initiatives in Vietnam merits further study.