New approaches in oral rotavirus vaccines

Strategies to Develop a Mucosa-Targeting Vaccine against Emerging Infectious Diseases

Numerous pathogenic microbes, including viruses, bacteria, and fungi, usually infect the host through the mucosal surfaces of the respiratory tract, gastrointestinal tract, and reproductive tract. The mucosa is well known to provide the first line of host defense against pathogen entry by physical, chemical, biological, and immunological barriers, and therefore, mucosa-targeting vaccination is emerging as a promising strategy for conferring superior protection. However, there are still many challenges to be solved to develop an effective mucosal vaccine, such as poor adhesion to the mucosal surface, insufficient uptake to break through the mucus, and the difficulty in avoiding strong degradation through the gastrointestinal tract. Recently, increasing efforts to overcome these issues have been made, and we herein summarize the latest findings on these strategies to develop mucosa-targeting vaccines, including a novel needle-free mucosa-targeting route, the development of mucosa-targeting vectors, the administration of mucosal adjuvants, encapsulating vaccines into nanoparticle formulations, and antigen design to conjugate with mucosa-targeting ligands. Our work will highlight the importance of further developing mucosal vaccine technology to combat the frequent outbreaks of infectious diseases.

G3 and G9 Rotavirus genotypes in waste water circulation from two major metropolitan cities of Pakistan

Rotavirus A (RVA) is a diarrheal pathogen affecting children under age five, particularly in developing and underdeveloped regions of the world due to malnutrition, poor healthcare and hygienic conditions. Water and food contamination are found to be major sources of diarrheal outbreaks. Pakistan is one of the countries with high RVA related diarrhea burden but with insufficient surveillance system. The aim of this study was to gauge the RVA contamination of major open sewerage collecting streams and household water supplies in two major metropolitan cities of Pakistan. Three concentration methods were compared using RNA purity and concentration as parameters, and detection efficiency of the selected method was estimated. Water samples were collected from 21 sites in Islamabad and Rawalpindi in two phases during the year 2014-2015. Meteorological conditions were recorded for each sampling day and site from Pakistan Meteorological Department (PMD). Nested PCR was used to detect the presence of RVA in samples targeting the VP7 gene. Logistic regression was applied to assess the association of weather conditions with RVA persistence in water bodies. Statistical analysis hinted at a temporal and seasonal pattern of RVA detection in water. Phylogenetic analysis of selected isolates showed a close association of environmental strains with clinical RVA isolates from hospitalized children with acute diarrhea during the same period. This is the first scientific report cataloging the circulating RVA strains in environmental samples from the region. The study highlights the hazards of releasing untreated sewerage containing potentially infectious viral particles into collecting streams, which could become a reservoir of multiple pathogens and a risk to exposed communities. Moreover, routine testing of these water bodies can present an effective surveillance system of circulating viral strains in the population.

Therapeutics and Immunoprophylaxis Against Noroviruses and Rotaviruses: The Past, Present, and Future

Background:

Noroviruses and rotaviruses are important viral etiologies of severe gastroenteritis. Noroviruses are the primary cause of nonbacterial diarrheal outbreaks in humans, whilst rotaviruses are a major cause of childhood diarrhea. Although both enteric pathogens substantially impact human health and economies, there are no approved drugs against noroviruses and rotaviruses so far. On the other hand, whilst the currently licensed rotavirus vaccines have been successfully implemented in over 100 countries, the most advanced norovirus vaccine has recently completed phase-I and II trials.

Methods:

We performed a structured search of bibliographic databases for peer-reviewed research litera-ture on advances in the fields of norovirus and rotavirus therapeutics and immunoprophylaxis.

Results:

Technological advances coupled with a proper understanding of viral morphology and replication over the past decade has facilitated pioneering research on therapeutics and immunoprophylaxis against noroviruses and rotaviruses, with promising outcomes in human clinical trials of some of the drugs and vaccines. This review focuses on the various developments in the fields of norovirus and rotavirus thera-peutics and immunoprophylaxis, such as potential antiviral drug molecules, passive immunotherapies (oral human immunoglobulins, egg yolk and bovine colostral antibodies, llama-derived nanobodies, and anti-bodies expressed in probiotics, plants, rice grains and insect larvae), immune system modulators, probiot-ics, phytochemicals and other biological substances such as bovine milk proteins, therapeutic nanoparti-cles, hydrogels and viscogens, conventional viral vaccines (live and inactivated whole virus vaccines), and genetically engineered viral vaccines (reassortant viral particles, virus-like particles (VLPs) and other sub-unit recombinant vaccines including multi-valent viral vaccines, edible plant vaccines, and encapsulated viral particles).

Conclusions:

This review provides important insights into the various approaches to therapeutics and im-munoprophylaxis against noroviruses and rotaviruses..

Oral Vaccine Delivery for Intestinal Immunity-Biological Basis, Barriers, Delivery System, and M Cell Targeting

Most currently available commercial vaccines are delivered by systemic injection. However, needle-free oral vaccine delivery is currently of great interest for several reasons, including the ability to elicit mucosal immune responses, ease of administration, and the relatively improved safety. This review summarizes the biological basis, various physiological and immunological barriers, current delivery systems with delivery criteria, and suggestions for strategies to enhance the delivery of oral vaccines. In oral vaccine delivery, basic requirements are the protection of antigens from the GI environment, targeting of M cells and activation of the innate immune response. Approaches to address these requirements aim to provide new vaccines and delivery systems that mimic the pathogen's properties, which are capable of eliciting a protective mucosal immune response and a systemic immune response and that make an impact on current oral vaccine development.

Drug therapy combined with systematic nursing for children with rotavirus enteritis: Therapeutic effect and impact on serum cytokines

AIM

To investigate the therapeutic effect of drug therapy combined with systematic nursing in children with rotavirus enteritis and the effect on serum cytokines.

METHODS

A total of 90 children with rotavirus enteritis treated at our hospital from July 2015 to August 2017 were selected and equally divided into either an observation group (Saccharomyces boulardii sachets + systematic nursing) or a control group (Saccharomyces boulardii sachets). After 3 d of treatment, the clinical efficacy of the two groups was evaluated, time to remission of clinical symptoms and the hospitalization time were recorded, and the levels of serum interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α were measured.

RESULTS

The total effective rate was significantly higher in the observation group than in the control group (93.33% vs 77.78%, P < 0.05). The time to remission of fever, dehydration, and diarrhea and hospitalization time were significantly shorter in the observation group than in the control group (3.02 d ± 0.97 d vs 4.57 d ± 1.04 d, 3.36 d ±1.67 d vs 5.84 d ± 1.49 d, 5.32 d ± 1.13 d vs 6.28 d ± 1.25 d, 5.98 d ± 2.11 d vs 7.83 d ±2.16 d; P < 0.05). After treatment, serum levels of IL-6, IL-10, and TNF-αin both groups significantly decreased (P < 0.05), and the decrease was significantly greater in the observation group than in the control group (70.21 pg/mL ± 16.84 pg/mL vs 78.58 pg/mL ± 18.63 pg/mL, 12.18 pg/mL ± 8.97 pg/mL vs 16.86 pg/mL ± 9.14 pg/mL, 3.48 pg/mL ± 1.08 pg/mL vs 4.39 pg/mL ± 1.13 pg/mL; P < 0.05).

CONCLUSION

Saccharomyces boulardii sachets combined with systematic nursing is an effective way to shorten the time to remission of clinical symptoms and hospitalization time and lower the levels of IL-6, IL-10, and TNF-α in children with rotavirus enteritis.

Delivery strategies to enhance oral vaccination against enteric infections

While the majority of human pathogens infect the body through mucosal sites, most licensed vaccines are injectable. In fact the only mucosal vaccine that has been widely used globally for infant and childhood vaccination programs is the oral polio vaccine (OPV) developed by Albert Sabin in the 1950s. While oral vaccines against Cholera, rotavirus and Salmonella typhi have also been licensed, the development of additional non-living oral vaccines against these and other enteric pathogens has been slow and challenging. Mucosal vaccines can elicit protective immunity at the gut mucosa, in part via antigen-specific secretory immunoglobulin A (SIgA). However, despite their advantages over the injectable route, oral vaccines face many hurdles. A key challenge lies in design of delivery strategies that can protect antigens from degradation in the stomach and intestine, incorporate appropriate immune-stimulatory adjuvants and control release at the appropriate gastrointestinal site. A number of systems including micro and nanoparticles, lipid-based strategies and enteric capsules have significant potential either alone or in advanced combined formulations to enhance intestinal immune responses. In this review we will outline the opportunities, challenges and potential delivery solutions to facilitate the development of improved oral vaccines for infectious enteric diseases.