Rotavirus and norovirus infections in children in Sana'a, Yemen

Objectives To describe the epidemiology of rotavirus and norovirus infection among children with acute gastroenteritis in Sana’a, Yemen. Methods A cross‐sectional study from November 2007 to March 2009 of children aged 1 month to 5 years attending the emergency and outpatient departments of two hospitals in Sana’a with acute gastroenteritis. Rotavirus was detected by ELISA and genotyped by RT‐PCR. Norovirus was detected by End Point RT‐PCR and nucleotide sequencing. Results A total of 290 children (48% in the emergency department and 52% in the outpatient department of the children respectively) were enrolled. Rotavirus infections were detected in 78 (27%) and norovirus infections in 30 (10%). Rotavirus genotypes included G1P[8] (55%), G9P[8] (21%) and G2P[4] (12%) with G12 comprising 3% of strain types. The main norovirus genotype was GII.4 (27%) with >10 other genotypes detected. Conclusions Rotavirus and norovirus infections are common causes of gastroenteritis in Yemen. Rotavirus vaccines could play a significant role in the control of acute childhood diarrhoea in this setting.     

2011年和2013年武汉市病毒性胃肠炎病原监测与分析

目的监测和分析2011年和2013年武汉市婴幼儿和成人病毒性胃肠炎病原。方法用聚丙烯酰胺凝胶电泳及RT-PCR对胃肠炎患者腹泻大便样本进行轮状病毒、诺如病毒、星状病毒以及札幌样病毒检测,部分样本测序并比对同源性。用PCR检测腺病毒。结果轮状病毒、诺如病毒、星状病毒、札幌样病毒检出率分别为21.6%(296/1 368)、35.7%(488/1 368)、10.2%(140/1 368)和7.7%(105/1 368);肠道腺病毒在儿童患者中的检出率为8.2%(70/853)。诺如病毒和轮状病毒易感人群为13~24月龄和7~24月龄儿童,及40~59岁成人。轮状病毒检出高峰在秋冬季。星状病毒、札幌样病毒和腺病毒多发于2岁以下的婴幼儿,无明显季节分布。196人份A组轮状病毒基因型以G9P[8]为主(40.8%),其次为G1P[8](26.5%),G3P[8](16.3%)和G2P[4](11.7%)。经测序比对诺如病毒基因型分别为GⅡ.4型(7/12),GⅡ.3型(5/12);星状病毒为1型(8/13),8型(4/13)和5型(1/13);札幌样病毒为GI.1型(2/6),GI 2型(2/6)和GⅡ.1型(2/6)。结论 2011年和2013年武汉市婴幼儿和成人胃肠炎主要病原是诺如病毒,其次是轮状病毒。     

Diarrhea caused by viruses in transplant recipients

Diarrhea is a common complication after solid organ transplantation, and viruses are emerging as important but underestimated causative agents. Viral infections in solid organ transplant (SOT) recipients can result in severe and prolonged diarrhea with significant patient morbidity and graft complications. Cytomegalovirus remains the most common of the viruses to cause diarrhea, but other viruses are being increasingly recognized, including norovirus, rotavirus, and adenovirus. This article reviews the epidemiology, clinical presentation, diagnosis, management, and outcomes of these viral causes of diarrhea in SOT patients.     

Mucosal and systemic neutralizing antibodies to norovirus induced in infant mice orally inoculated with recombinant rotaviruses

Rotaviruses (RVs) preferentially replicate in the small intestine and frequently cause severe diarrheal disease, and the following enteric infection generally induces variable levels of protective systemic and mucosal immune responses in humans and other animals. Rhesus rotavirus (RRV) is a simian RV that was previously used as a human RV vaccine and has been extensively studied in mice. Although RRV replicates poorly in the suckling mouse intestine, infection induces a robust and protective antibody response. The recent availability of plasmid only-based RV reverse genetics systems has enabled the generation of recombinant RVs expressing foreign proteins. However, recombinant RVs have not yet been experimentally tested as potential vaccine vectors to immunize against other gastrointestinal pathogens in vivo. This is a newly available opportunity because several live-attenuated RV vaccines are already widely administered to infants and young children worldwide. To explore the feasibility of using RV as a dual vaccine vector, we rescued replication-competent recombinant RRVs harboring bicistronic gene segment 7 that encodes the native RV nonstructural protein 3 (NSP3) protein and a human norovirus (HuNoV) VP1 protein or P domain from the predominant genotype GII.4. The rescued viruses expressed HuNoV VP1 or P protein in infected cells in vitro and elicited systemic and local antibody responses to HuNoV and RRV following oral infection of suckling mice. Serum IgG and fecal IgA from infected suckling mice bound to and neutralized both RRV and HuNoV. These findings have encouraging practical implications for the design of RV-based next-generation multivalent enteric vaccines to target HuNoV and other human enteric pathogens.

Mucosal immunity plays a critical role in protecting against many pathogens in the respiratory and intestinal tracts. Live virus infections generally trigger more robust and effective mucosal immune response than oral administration of inactivated viruses or target protein antigens because they are self-amplifying and can more effectively elicit cellular as well as humoral immunity (1–4). Several studies have attempted to utilize recombinant viruses as vaccine vectors to induce an immune response against enteric pathogens (5–8); however, the most advanced of such enteric vaccine vectors are still in early stages of clinical development.Rotaviruses (RVs), the leading cause of acute gastroenteritis in infants, are a promising candidate for enteric vaccine vectors for several reasons. A) RV preferentially replicates in the small intestine, distinguishing it from several other enteric viruses that can also infect systemically or the colon. B) RV infection is acute, and the virus does not integrate into the host genome. C) RV is highly immunogenic and induces both systemic and mucosal immune responses in infected animals and humans (9, 10). D) Several live-attenuated human RV vaccines have been shown to be both safe and effective to use in very young children [e.g., RotaTeq (Merck) and Rotarix (GlaxoSmithKline)]. Other effective live-attenuated RV vaccines [Rotasiil, Rotavac, Lanzhou lamb rotavirus vaccine (LLR), and Rotavin-M1] are also licensed for use globally or primarily in their country of origin (11). E) Following substantial public health efforts, RV vaccines are now widely available in many low- and middle-income countries, as well as the more developed countries, and hence the administration of RV-based vaccines that included other heterologous antigens could potentially be piggybacked onto current RV immunization programs used globally. F) The RV double-stranded RNA (dsRNA) genome is segmented in nature, permitting easy genetic manipulation. G) With the insertion of heterologous antigens, RV replication can become attenuated in vitro (12, 13).Since a plasmid-based reverse genetics system was established in 2017, several studies have reported the generation of recombinant RVs that express fluorescent and bioluminescent reporter proteins (GFP, RFP, luciferase, etc.) and exogenous nucleotide sequences [e.g., endoribonuclease Csy4 target sequence and sequences encoding the receptor binding domain of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein] in vitro (12–22). To facilitate the assessment and development of RVs as potential enteric vaccine vectors, the capacity of recombinant RVs to induce an enteric immune response against other gastrointestinal (GI) pathogens needs to be evaluated in well-characterized preclinical small animal models. Rhesus rotavirus (RRV) is a prototype laboratory strain of simian RV that efficiently replicates in vitro (23, 24). Although RRV does not replicate well in a murine model (25–27), it does induce both systemic and mucosal immune responses in infected mice (28). In addition, RRV itself and RRV-based RV vaccine candidates have previously been shown to be a highly immunogenic and protective in several human vaccine trials and were, for a time, licensed for use in children in the United States (29, 30).Human norovirus (HuNoV) is a major cause of acute gastroenteritis in both young children and adults. Although B cells and human intestinal organoids support HuNoV replication (31, 32), there is not yet a widely available robust cell culture system for efficient HuNoV cultivation, which has impeded both the assessment of HuNoV immunity and vaccine development. The HuNoV virion consists of major capsid protein VP1 and minor capsid protein VP2 surrounding a positive-sense RNA genome (33–35). Exogenously expressed VP1 can form virus-like particles (VLPs) that are structurally and antigenically similar to HuNoV virions (36–38), and the parenteral administration of such VLPs provides some level of protective immunity to HuNoV in adults (39–41). Moreover, expression of the protruding or P domain of VP1 that bears the major antigenic sites of HuNoV can yield subunit “P particles” that can also induce immune responses (42, 43). Here, we demonstrate the induction of both systemic and mucosal antibody responses against HuNoV in suckling mice using recombinant RRVs expressing HuNoV VP1 or P domain. Our data suggest that recombinant RVs represent a potentially effective small-intestine–targeted vaccination platform to express exogenous genes in the human intestine and to protect people from other enteric pathogens such as HuNoV as well as RV.     

Viral Etiologies of Acute Dehydrating Gastroenteritis in Pakistani Children: Confounding Role of Parechoviruses

Despite substantial interventions in the understanding and case management of acute gastroenteritis, diarrheal diseases are still responsible for a notable amount of childhood deaths. Although the rotavirus is known to cause a considerable burden of pediatric diarrheal cases, the roles of other viruses remain undefined for the Pakistani population. This study was based on tertiary care hospital surveillance, from January 2009 to December 2010, including the detection of rotavirus, norovirus, astrovirus, and human parechovirus in children under the age of five using serological or molecular assays. Rotavirus, human parechovirus, norovirus, and astrovirus were detected in 66%, 21%, 19.5%, and 8.5% subjects, respectively. Human parechovirus genotypes, determined through analysis of VP1 gene sequences, showed a great diversity among co-circulating strains. Eighty percent of hospitalized children had dual or multiple viral infections, while 98% parechovirus positive cases were co-infected with rotavirus. The remarkable diversity of viruses associated with the childhood diarrhea in Pakistan calls for large-scale epidemiological surveys, coupled with case control studies, to ascertain their role in clinical manifestations. In addition, these findings also highlight the need for the implementation of up-to-date health interventions, such as the inclusion of a rotavirus vaccine in routine immunization programs for the improvement of quality in child health care.     

A Nanoparticle-Based Trivalent Vaccine Targeting the Glycan Binding VP8* Domains of Rotaviruses

Rotavirus causes severe gastroenteritis in children. Although vaccines are implemented, rotavirus-related diarrhea still claims ~200,000 lives annually worldwide, mainly in low-income settings, pointing to a need for improved vaccine tactics. To meet such a public health need, a P₂₄-VP8* nanoparticle displaying the glycan-binding VP8* domains, the major neutralizing antigens of rotavirus, was generated as a new type of rotavirus vaccine. We reported here our development of a P₂₄-VP8* nanoparticle-based trivalent vaccine. First, we established a method to produce tag-free P₂₄-VP8* nanoparticles presenting the VP8*s of P[8], P[4], and P[6] rotaviruses, respectively, which are the three predominantly circulating rotavirus P types globally. This approach consists of a chemical-based protein precipitation and an ion exchange purification, which may be scaled up for large vaccine production. All three P₂₄-VP8* nanoparticle types self-assembled efficiently with authentic VP8*-glycan receptor binding function. After they were mixed as a trivalent vaccine, we showed that intramuscular immunization of the vaccine elicited high IgG titers specific to the three homologous VP8* types in mice. The resulted mouse sera strongly neutralized replication of all three rotavirus P types in cell culture. Thus, the trivalent P₂₄-VP8* nanoparticles are a promising vaccine candidate for parenteral use against multiple P types of predominant rotaviruses.     

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.     

Viral Enteritis in Solid-Organ Transplantation

Solid organ transplant recipients are at increased risk for infections due to chronic immunosuppression. Diarrhea is a commonly encountered problem post transplantation, with infectious causes of diarrhea being a frequent complication. Viral infections/enteritides in solid organ transplant recipients often result from frequently encountered pathogens in this population such as cytomegalovirus, adenovirus, and norovirus. However, several emerging viral pathogens are increasingly being recognized as more sensitive diagnostic techniques become available. Treatment is often limited to supportive care and reduction in immunosuppression, though antiviral therapies mayplay a role in the treatment in certain diseases. Viral enteritis is an important entity that contributes to morbidity and mortality in transplant recipients.