ACUTE GASTROENTERITIS ASSOCIATED WITH NOROVIRUS GII.4 VARIANTS

Norovirus strains in patients with acute gastroenteritis in rural and low-income urban areas in northern Brazil

From 2010-2016, a total of 251 stool samples were screened for norovirus using next-generation sequencing (NGS) followed by phylogenetic analysis to investigate the genotypic diversity of noroviruses in rural and low-income urban areas in northern Brazil. Norovirus infection was detected in 19.9% (50/251) of the samples. Eight different genotypes were identified: GII.4_Sydney[P31] (64%, 32/50), GII.6[P7] (14%, 7/50), GII.17[P17] (6%, 3/50), GII.1[P33] (6%, 3/50), GII.3[P16] (4%, 2/50), GII.2[P16] (2%, 1/50), GII.2[P2] (2%, 1/50), and GII.4_New Orleans[P4] (2%, 1/50). Distinct GII.6[P7] variants were recognized, indicating the presence of different co-circulating strains. Elucidating norovirus genetic diversity will improve our understanding of their potential health burden, in particular for the GII.4_Sydney[P31] variant.

Norovirus-associated gastroenteritis, Pernambuco, Northeast Brazil, 2014-2017

Norovirus (NoV) is currently the leading cause of nonbacterial gastroenteritis. In Brazil, few studies have characterized the molecular, epidemiological and clinical features of NoV-associated gastroenteritis. This study aimed to describe the molecular and clinicoepidemiological findings of NoV infections in patients of all ages throughout Pernambuco state, Northeast Brazil. Thus, 1135 stool samples were analyzed from patients with gastroenteritis from Pernambuco state. NoV was detected by enzyme immunoassay in 125 (11.01%) samples. Regarding gender distribution, 55 (44.00%) patients were female and 70 (56.00%) male. Their ages ranged from 5 days to 87 years, and the group most affected by NoV infection (88.00%) was children under 3 years. Complete clinical information was available for 88 out of 125 NoV-positive patients. Diarrhea was present in all patients and vomiting was reported in 60 patients (68.68%). Nine patients (10.22%) had bloody stools and 46 (52.27%) had a fever, with temperatures ranging from 37.90°C to 39.90°C (mean 38.20°C). NoV was detected mainly in the summer-autumn seasons. Genome sequencing and phylogenetic analyses identified four different NoV GII genotypes circulating in this area of the country. Therefore, our study provided valuable information about the clinics and epidemiology of NoV infection in tropical settings and will assist health authorities to develop better control strategies against this important pathogen.

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.

Virus-Like Particles-Based Mucosal Nanovaccines

Virus-like particles (VLPs) are protein complexes that resemble a virus and constitute highly immunogenic entities as they mimic the pathogen at an important degree. Among nanovaccines, those based on VLPs are the most successful thus far with some formulations already commercialized (e.g., those against hepatitis B and E viruses and human papillomavirus). This chapter highlights the advantages of VLPs-based vaccines, describing approaches for their design and transmittance of the state of the art for mucosal VLPs-based vaccines development. Several candidates have been produced in insect cells, plants, and E. coli and mammalian cells; they have been mainly evaluated in i.n. and oral immunization schemes. i.n. vaccines against the influenza virus and the Norwalk virus are the most advanced applications. For the latter, i.n. formulations are under clinical evaluation. Perspectives for the field comprise the expansion of the use of low-cost platforms such as plants and bacteria, the development of multiepitopic/multivalent vaccines, and computationally designed VLPs. Mucosal VLPs-based vaccines stand as a major promising approach in vaccinology and the initiation of more clinical trials is envisaged in a short time.