An oral NoV-rAd5 vaccine with built-in dsRNA adjuvant elicits systemic immune responses in mice.

Norovirus (NoV) is an enteric pathogen notorious for causing epidemics of acute gastroenteritis. An effective vaccine against NoV is therefore urgently needed. A short double-stranded RNA (dsRNA) has been described that acts as a retinoic-acid-inducible gene-I agonist to induce the production of type I interferon; it also exhibits adjuvant activity. Using built-in dsRNA of different lengths (DS1 and DS2), we developed a recombinant adenovirus 5 (rAd5) expressing NoV VP1, and evaluated its immunogenicity following oral administration in a mouse model. An in vitro study demonstrated that the dsRNA adjuvants significantly enhanced VP1 protein expression in infected cells. The oral administration of both rAd5-VP1-DS vaccines elicited high serum levels of VP1-specific IgG and blocking antibodies, as well as strong and long-lasting mucosal immunity. There was no apparent difference in immunostimulatory effects in immunised mice between the two dsRNA adjuvants. This study indicates that an oral NoV-rAd5 vaccine with a built-in dsRNA adjuvant may be developed to prevent NoV infection in humans.

Phylogenetic analysis of the viral proteins VP4/VP7 of circulating human rotavirus strains in China from 2016 to 2019 and comparison of their antigenic epitopes with those of vaccine strains.

Group A rotaviruses (RVAs) are the most common etiological agents of severe acute diarrhea among children under 5 years old worldwide. At present, two live-attenuated RVA vaccines, LLR (G10P[15]) and RotaTeq (G1-G4, G6 P[8], P[5]), have been introduced to mainland China. Although RVA vaccines can provide homotypic and partially heterotypic protection against several strains, it is necessary to explore the genetic and antigenic variations between circulating RVAs and vaccine strains. In this study, we sequenced viral protein VP7 and VP4 outer capsid proteins of 50 RVA strains circulating in China from 2016 to 2019. The VP7 and VP4 sequences of almost all strains showed high homology to those of previously reported human strains and vaccine strains of the same genotype. However, in the presumed antigenic epitopes of the VP7 and VP4, multiple amino acid variations were found, regardless of the G and P genotypes of these strains. Moreover, all circulating G3 RVA strains in China potentially possess an extra N-linked glycosylation site compared with the G3 strain of RotaTeq. The potential N-linked glycosylation site at residues 69-71 was found in all G9 strains in China but not in the G9 strain of the Rotavac or Rotasill vaccine. These variations in antigenic sites might result in the selection of strains that escape the RVA neutralizing-antibody pressure imposed by vaccines. Furthermore, the G4 and P[6] genotypes in this study showed high homology to those of porcine strains, indicating the transmission of G4 and P[6] genotypes from pigs to humans in China. More genetic surveillance with antigenic evaluation in prevalent RVAs is necessary for developing and implementing rotavirus vaccines in China.

Genomic and evolutionary characteristics of G3P[8] group a rotavirus strains in China, 2016 to 2018.

Rotavirus A (RVA) G3P[8] is sporadically detected in China, although G9P[8] predominates. To evaluate their genetic composition at the whole-genome level, 24 G3P[8] RVA strains isolated from children under five years were sequenced and characterized. The 24 strains were genotyped as G3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, indicating the Wa-like genotype constellation. A maximum clade credibility (MCC) tree for VP7 indicated that G3 had an estimated mean evolutionary rate of 7.279 × 10-4 substitutions/site/year; thus, 3-5 years would pass from the generation of an ancestor virus to the epidemic spread of that virus throughout China. Considering the ongoing prevalence as well as rapid evolution, it is important to monitor G3P[8] RVA epidemics; continuous nationwide surveillance is essential.

Identification of a novel norovirus species in fox.

A novel Norovirus (NoV) was identified by viral metagenomic analysis in fox fecal samples from the Xinjiang Uygur Autonomous Region of China. The virus exhibited typical genomic characteristics of NoVs. It was closely related to the canine NoV GVII strains with 86.0-86.2% and 91.9% amino acid identities in the capsid protein VP1 and RNA-dependent RNA polymerase (RdRp), respectively. The fox NoV clustered phylogenetically with the two canine NoV GVII strains, and it was distant from other NoVs. According to the new classification criteria of NoVs, the new fox NoV belongs to the same genotype as GVII, similar to canine GVII NoVs. Moreover, key amino acid residues in the Histo-blood group antigen (HBGA) binding sites and the HBGA binding pattern of the fox NoV differed significantly from those of human and canine GVII NoVs. This study identified a new GVII norovirus from wild foxes in China. These findings enrich our understanding of the diversity of NoVs and provide further evidence regarding the genetic heterogeneity of NoVs in carnivores.

The Functional Characterization of Bat and Human P[3] Rotavirus VP8*s.

P[3] rotavirus (RV) has been identified in many species, including human, simian, dog, and bat. Several glycans, including sialic acid, histo-blood group antigens (HBGAs) are reported as RV attachment factors. The glycan binding specificity of different P[3] RV VP8*s were investigated in this study. Human HCR3A and dog P[3] RV VP8*s recognized glycans with terminal sialic acid and hemagglutinated the red blood cells, while bat P[3] VP8* showed neither binding to glycans nor hemagglutination. However, the bat P[3] VP8* mutant of C189Y obtained the ability to hemagglutinate the red blood cells, while human P[3] HCR3A/M2-102 mutants of Y189C lost the ability. Sequence alignment and structural analysis indicated that residue 189 played an important role in the ligand recognition and may contribute to the cross-species transmission. Structural superimposition exhibited that bat P[3] VP8* model was quite different from the simian P[3] Rhesus rotavirus (RRV) P[3] VP8*, indicating that bat P[3] RV was relatively distinct and partially contributed to the no binding to tested glycans. These results promote our understanding of P[3] VP8*/glycans interactions and the potential transmission of bat/human P[3] RVs, offering more insight into the RV infection and prevalence.

[P38 MAPK signaling pathway regulates nuclear factor-κB and inducible nitric oxide synthase expressions in the substantia nigra in a mouse model of Parkinson's disease].

OBJECTIVE: To investigate the role of P38 mitogen-activated protein kinase (P38 MAPK) signaling pathway in regulating the expression of nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) in the substantia nigra (SN) of a mouse model of Parkinson's disease (PD). METHODS: C57BL/6N mice were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to establish an subacute PD model, and the behavioral changes of the mice were observed. Immunohistochemistry and Western blotting were employed to detect the expressions of tyrosine hydroxylase (TH), NF-κB, iNOS and phosphorylated P38 (p-P38) in the midbrain before and after treatment with SB203580. RESULTS: Compared with the control mice, the PD mouse models presented with typical symptoms of PD and showed significantly increased number of p-P38-, NF-κB-, and iNOS-positive cells in the SN area (P<0.01) with significantly reduced number of TH-positive neurons (P<0.01). After SB203580 treatment, the number of p-P38-, NF-κB-, and iNOS-positive cells was reduced obviously (P<0.01) and the number of TH-positive neurons in the SN increased significantly in the PD model mice (P<0.01). CONCLUSION: P38 MAPK signaling pathway may play an important role in modulating NF-κB and iNOS expression in the SN in the early stage of MPTP-induced subacute PD, and SB203580 can inhibit P38 signaling pathway to protect the DA neurons in PD model mice.