Evaluation of Immunogenicity and Clinical Protection of SARS-CoV-2 S1 and N Antigens in Syrian Golden Hamster.

The novel coronavirus (SARS-CoV-2) epidemic continues to be a global public crisis affecting human health. Many research groups are developing different types of vaccines to suppress the spread of SARS-CoV-2, and some vaccines have entered phase III clinical trials and have been rapidly implemented. Whether multiple antigen matches are necessary to induce a better immune response remains unclear. To address this question, this study tested the immunogenicity and protective effects of a SARS-CoV-2 recombinant S and N peptide vaccine in the Syrian golden hamster model. This experiment was based on two immunization methods: intradermal and intramuscular administration. Immunized hamsters were challenged with live SARS-CoV-2 14 days after booster immunization. Clinical symptoms were observed daily, and the antibody titer and viral load in each tissue were detected. The results showed that immunization of golden hamsters with the SARS-CoV-2 structural protein S alone or in combination with the N protein through different routes induced antibody responses, whereas immunization with the N protein alone did not. However, although the immunized hamsters exhibited partial alleviation of clinical symptoms when challenged with the virus, neither vaccine effectively inhibited the proliferation and replication of the challenging virus. In addition, the pathological damage in the immunized hamsters was similar to that in the control hamsters. Interestingly, the neutralizing antibody levels of all groups including immunized and nonimmunized animals increased significantly after viral challenge. In conclusion, the immune response induced by the experimental S and N polypeptide vaccines had no significant ability to prevent viral infection and pathogenicity in golden hamsters.

Attenuated phenotypes and analysis of a herpes simplex virus 1 strain with partial deletion of the UL7, UL41 and LAT genes.

We previously constructed a herpes simplex virus 1 (HSV-1) UL7 mutant virus (M1) and showed that a partial deletion mutation of the UL7 gene led to a lower proliferative rate and an attenuated phenotype. Using the M1 mutant, we further modified the UL41 gene, which encodes another tegument protein, and the latency-associated transcript (LAT) gene. Observations of the resulting mutants with modified UL7 and UL41 (M2) or UL7, UL41 and LAT (M3) genes indicated attenuated phenotypes, with lower proliferative ratios in various cells, non-lethal infections in mice and lower viral loads in nervous tissues compared with the wild-type strain. Furthermore, no LAT stable intron could be detected in the trigeminal ganglion of M3-infected animals. The results obtained with the three HSV-1 mutants indicate that the M3 mutant is an attenuated strain with low pathogenicity during both acute and latent infections. Together, the results support the use of the M3 mutant as a candidate for the development of an HSV-1 vaccine.

A comparative study of the characteristics of two Coxsackie A virus type 16 strains (genotype B).

Coxsackie A virus is one of the major pathogens associated with hand, foot and mouth disease (HFMD). The etiological characteristics of Coxsackie A virus type 16 (CA16) are thought to correlate with the pathological process of its infection. Two CA16 strains that were isolated from a severe HFMD patient presented with different plaque forms. This observation, along with biological analysis, indicated that the differences in the strains' biological characteristics, such as proliferation kinetics and immunogenicity, correlate with differences in their pathogenicity toward neonatal mice. Furthermore, these differences are thought to be associated with the sequence of the 5' non-coding region of the viral genome and the VP1 structural region sequence. The results suggest that the biological and genetic characteristics of the CA16 viral strains are relevant to their pathogenicity.

Celastrus orbiculatus extract induces mitochondrial-mediated apoptosis in human hepatocellular carcinoma cells.

OBJECTIVE: To investigate the apoptotic effects and underlying molecular mechanisms of Celastrus orbiculatus (C. orbiculatus) extract in human hepatocellular carcinoma cells. METHODS: Human hepatocellular carcinoma cells (HCCLM6) were treated with C. orbiculatus extract (COE) at different nontoxic concentrations (10, 20, 40, 80, and 160 microg/mL). The effect of COE on HCCLM6 viability was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays. Cellular apoptosis following COE treatment was assessed by flow cytometry and western blot analysis. RESULTS: COE significantly inhibited cell viability and induced apoptosis of HCCLM6 cells in a dose-dependent manner. Apoptosis was accompanied by increased Bax expression and decreased Bcl-2 expression. In addition, COE treatment led to the release of cytochrome c, activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP). Furthermore, activation of extracellular signal-regulated kinase (ERK), p38 kinase, and c-Jun N-terminal kinase (JNK) phosphorylation, and down-regulation of Akt phosphorylation was observed. CONCLUSION: COE induces mitochondrial-mediated, caspase-dependent apoptosis in HCCLM6 cells, which might be attributed to the activation of mitogen-activated protein kinase (MAPK) and inhibition of Akt signaling pathways. These data suggest that COE may be a potential treatment for human hepatocellular carcinoma.

A comparison of the biological characteristics of EV71 C4 subtypes from different epidemic strains.

The comparative analysis of the biological characterization and the genetic background study of EV71 circulating strains is commonly recognized as basic work necessary for development of an effective EV71 vaccine. In this study, we sequenced five EV71 circulating strains, isolated from Fuyang, Hefei, Kunming and Shenzhen city of China and named them FY-23, FY-22, H44, K9 and S1 respectively. The sequence alignment demonstrated their genotypes be C4. The genetic distance of the VP1 gene from these isolates suggested that they were highly co-related with genetic identity similar to other previously reported EV71 strains in China. Additionally, these strains were identified to display some obvious proliferation dynamics and plaque morphology when propagated in Vero cells. However, a distinctive difference in pathogenic ability in neonatal mice was found. Some differences in cross neutralization test & immunogenic analysis were also found. All these results are related to the biological characterization of circulating EV71 strains in China and aid in the development of an EV71 vaccine in the future.