The design of the mRNA vaccine involves the selection of in vitro transcription (IVT) systems and nonviral delivery vectors. This study aimed to verify the effect of 5’ and 3’ untranslated region (UTR) sequences on the translation efficiency of mRNA. Three modes of IVT-mRNA systems (IVT-mRNA-n1/n2/n3) with diverse UTRs were constructed, and EGFP (enhanced green fluorescent protein) and HA (hemagglutinin) gene of H3N2 influenza virus were introduced into each of them. The results showed that the mode of 5’ and 3’ UTRs originating from human β-globulin was better than the mode of UTRs from human α-globulin, and the n3 mode was the best. mEGFP-n3, mH3HA-n3, and mLuciferease-n3 were prepared to compare the effect of cationic lipid nanoparticle (LNP) with that of mannose-conjugated LNP (LNP-Man) on the efficiency of gene delivery. The results showed that the effect of LNP-Man was better than that of LNP both in vitro and in vivo. Choosing appropriate ligands might help in vaccine design. After selecting the IVT-mRNA-n3 system and delivery vectors, mRNA vaccines were constructed against the H1N1 influenza virus, and C57BL/6 mice were immunized through intranasal administration. The results showed that mRNA vaccines could elicit both humoral and cellular immune responses and completely protect mice from the tenfold LD₅₀ H1N1 influenza virus challenge.

Porcine circovirus type 3 (PCV3) is a novel circovirus that was firstly detected in the USA. PCV3 is associated with porcine dermatitis and nephropathy syndrome (PDNS), reproductive failure and cardiac and multisystemic inflammation. Latterly, PCV3 was detected in Guangxi, China. Forty‐one of 108 (37.96%) samples and nine of 47 (19.14%) samples were PCV3 positive in pig farms and pig slaughter houses, respectively. Three PCV3 strains were sequenced and designated PCV3‐China/GX2016‐1, PCV3‐China/GX2016‐2 and PCV3‐China/GX2016‐3. The complete genome of PCV3‐China/GX2016‐2 and PCV3‐China/GX2016‐3 is both 2,000 bp in length, while PCV3‐China/GX2016‐1 is of 1,999 bp and has a G deletion at position of 1,155 in its genome. The complete genome and capsid nucleotide of the three PCV3 strains identified in this study shared 97.5%–99.4% and 96.7%–99.1% identities with that of the other PCV3 strains available in NCBI, respectively. Phylogenetic analysis based on complete genome and capsid gene of 35 PCV3 strains showed that the three PCV3 sequences from Guangxi Province were divided into two clusters. The results of this study contribute to the understanding of PCV3 molecular epidemiology.

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus (PCVs) are two major viruses that affect pigs. Coinfections between PRRSV and PCV2 are frequently reported in most outbreaks, with clinical presentations involving dyspnea, fever, reduced feed intake, weight loss, and death in fattening pigs. The NADC30-like PRRSV and PCV2d are the main circulating virus strains found in China. This study determines the impact of NADC30-like PRRSV and PCV2d mono-infection and coinfection on the immune system, organ pathology, and viral shedding in five-week-old post-weaned pigs. Pigs were randomly divided into six groups: PBS, PRRSV, PCV2, PRRSV-PCV2 coinfection (co), and PRRSV-PCV2 or PCV2-PRRSV sequential infections. Fever, dyspnea, decreased feed intake, weight loss, and pig deaths occurred in groups infected with PRRSV, Co-PRRSV-PCV2, and PRRSV-PCV2. The viral load was higher in Co-PRRSV-PCV2, PRRSV-PCV2, and PCV2-PRRSV than those mono-infected with PRRSV or PCV2. Additionally, cytokines (IFN-γ, TNF-α, IL-4, and IL-10) produced by pigs under Co-PRRSV-PCV2 and PRRSV-PCV2 groups were more intense than the other groups. Necropsy findings showed hemorrhage, emphysema, and pulmonary adhesions in the lungs of pigs infected with PRRSV. Smaller alveoli and widened lung interstitium were found in the Co-PRRSV-PCV2 and PRRSV-PCV2 groups. In conclusion, PRRSV and PCV2 coinfection and sequential infection significantly increased viral pathogenicity and cytokine responses, resulting in severe clinical signs, lung pathology, and death.

The Getah virus (GETV), a mosquito-borne RNA virus, is widely distributed in Oceania and Asia. GETV is not the only pathogenic to horses, pigs, cattle, foxes and boars, but it can also cause fever in humans. Since its first reported case in Chinese mainland in 2017, the number of GETV-affected provinces has increased to seventeen till now. Therefore, we performed an epidemiologic investigation of GETV in the Xinjiang region, located in northwestern China, during the period of 2017–2020. ELISA was used to analyze 3299 serum samples collected from thoroughbred horse, local horse, sheep, goat, cattle, and pigs, with thoroughbred horse (74.8%), local horse (67.3%), goat (11.7%), sheep (10.0%), cattle (25.1%) and pigs (51.1%) being positive for anti-GETV antibodies. Interestingly, the neutralizing antibody titer in horses was much higher than in other species. Four samples from horses and pigs were positive for GETV according to RT-PCR. Furthermore, from the serum of a local horse, we isolated GETV which was designated as strain XJ-2019-07, and determined its complete genome sequence. From the phylogenetic relationships, it belongs to the Group III lineage. This is the first evidence of GETV associated to domestic animals in Xinjiang. Overall, GETV is prevalent in Xinjiang and probably has been for several years. Since no vaccine against GETV is available in China, detection and monitoring strategies should be improved in horses and pigs, especially imported and farmed, in order to prevent economic losses.

Pyroptosis is related to the occurrence, development, and therapeutic response of tumors, mediated by the proteins of the Gasdermin family. These proteins have become potential biomarkers for cancer treatment, and their agonists are likely to become a new direction in research and development of antitumor drugs. In this study, we found that myricetin has an inhibitory effect on lung cancer cells of the activation of pyroptosis. Analysis of the expression of Gasdermin family proteins revealed that this phenomenon was caused by the cleavage of GSDME. Subsequently, specific inhibitors, we found that caspase-3 was its upstream activation factor. In addition, mitochondrial and endoplasmic reticulum (ER) analysis showed that myricetin can cause endoplasmic reticulum stress and increase reactive oxygen species (ROS) levels. Subsequent inhibition of caspase-12 revealed that the expression levels of cleaved-caspase-3 and cleaved-GSDME were significantly reduced, resulting in the inhibition of pyroptosis. Using in vivo experiments, we also found that the treatment with myricetin can reduce tumor volume and significantly increase the level of pyroptosis-related proteins in tumor tissues. Overall, our findings show that myricetin induces cell death of lung cancer cells primarily through an ER stress pathway-induced pyroptosis. Therefore, myricetin has the potential to be used as a pyroptosis agonist in research and development of antitumor drugs.