Archives of Virology最新文献

In this study, a lytic phage, named PG216, was obtained from seawater collected in Qingdao, using Vibrio parahaemolyticus strain G299 as its host. Transmission electron microscopy revealed that phage PG216 has an icosahedral head with a diameter of 100 ± 6.7 nm and a contractible tail with a length of 126 ± 6.7 nm. The spot assay and EOP assay for host range testing revealed that the phage displayed extensive lytic activity against five Vibrio species: V. alginolyticus, V. parahaemolyticus, V. vulnificus, V. mimicus, and V. harveyi. The one-step growth curve indicated that the phage has a latent period of 25 min, a lysis duration of 115 min, and an average burst size of 135 ± 02 PFU/cell. The genome of PG216 is 244,027 bp in length with a GC content of 42.89%, and itcontains383 ORFs and encodes 28 tRNAs. Phylogenetic analysis suggested that PG216 belongs to the genus Schizotequatrovirus within the family Straboviridae. Phage PG216 was found to be able to eradicate mature biofilms produced by V. parahaemolyticus G299. Phage PG216 demonstrates notable lytic activity while lacking virulence and antibiotic-resistance genes and therefore might be a viable candidate for use in phage therapy of vibriosis.

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis in the Asia-Pacific region. Amplification of JEV in pigs is a potent driver for spillover of the infection to humans, and hence monitoring of virus dynamics in pigs can provide insights into JEV ecology. To study the dynamics of natural JEV infection in a tropical region, two groups of immunologically naïve pigs consisting of six animals per group were kept as sentinels on two different farms in the district of Thanjavur, Tamil Nadu, India. In a longitudinal study conducted from May 2022 to October 2023, nested RT-PCR and indirect ELISA were used to track the dynamics of JEV and the humoral response in pigs. Synchronous and asynchronous seroconversion in pigs was recorded on two different farms with different management practices. Repeated infections with JEV were recorded in all of the sentinel animals throughout the study period, irrespective of the season. Phylogenetic analysis revealed the presence of JEV genotype III in the region. It was observed that the IgG response to natural JEV infection did not last long, which might have been the reason for repeated infections in the sentinel animals. The longest period during which IgG was present at detectable levels in this study was two months, after which the pigs could once again amplify the virus. A significant positive correlation was found between wind speed and JEV incidence in sentinel animals. Our results offer a different perspective on the relationship between JEV and its amplifying host that contradicts the assumption that pre-immune pigs are resistant to JEV amplification. Our findings could have a major impact on our understanding of the ecology of JEV in tropical regions, where there is a high burden of JE despite coordinated prevention efforts that have relied on achieving a long-lasting immune response.

To battle seasonal outbreaks of influenza B virus infection, which continue to pose a major threat to world health, new and improved vaccines are urgently needed. In this article, we discuss the current state of next-generation influenza B vaccine development, including both advancements and challenges. This review covers the shortcomings of existing influenza vaccines and stresses the need for more-effective and broadly protective vaccines and more-easily scalable manufacturing processes. New possibilities for vaccine development have emerged due to recent technical developments such as virus-like particle (VLP) platforms, recombinant DNA technologies, and reverse genetics. By using these methods, vaccines can be developed that elicit stronger and longer-lasting immune responses against various strains of influenza B virus. Vaccines may be more effective and immunogenic when adjuvants and new delivery mechanisms are used. Progress has been made in the development of influenza B vaccine mRNA vaccines, nanoparticle-based vaccines, and vector-based vaccines. However, there are still several obstacles to overcome before next-generation influenza B vaccines can be widely used, including the challenge of antigenic drift, the extinction of the B/Yamagata lineage, and difficulties in strain selection. There are also other challenges related to public acceptance, vaccine distribution, manufacturing complexity, and regulations. To overcome these challenges, scientists, politicians, and pharmaceutical firms must work together to expedite the development and licensing of vaccines and the establishment of immunization programs. The need for constant monitoring and quick adaptation of vaccines to match the currently circulating strains is further highlighted by the appearance of novel influenza B virus variants. To be ready for future pandemics and influenza B outbreaks, we need better vaccines and better monitoring systems.

The I38T substitution in the influenza virus polymerase-acidic (PA) subunit is a resistance marker of concern for treatment with the antiviral baloxavir marboxil (BXM). Thus, monitoring PA/I38T mutations is of clinical importance. Here, we developed three rapid and sensitive assays for the detection and monitoring of the PA/I38T mutation. In addition, we updated our previously developed methods to monitor the D197N mutation in the neuraminidase (NA) of influenza B virus, which is associated with resistance to oseltamivir. Real-time PCR high-resolution melting analysis (HRMA) was developed for the rapid detection of the PA/I38T and NA/D197N mutations using oligonucleotides with substitutions of interest and influenza viruses isolated in our laboratory. HRMA was subsequently performed on 94 clinical samples that were positive for A/H1N1pdm09, A/H3N2, and type-B influenza viruses and on viruses that were selected in vitro to grow in the presence of BXA (baloxavir acid, BXM active compound). The HRMAs were able to discriminate PA/I38 from the PA/I38T mutation and NA substitutions in synthetic oligonucleotides. However, the I38T mutation and NA mutations were not detected in any of our clinical samples, indicating the absence of these resistance markers in the circulating viruses examined. Only one out of 43 A/H3N2 clinical samples analyzed contained a virus with mutations associated with resistance to oseltamivir. All the HRMA results were confirmed by sequencing. Finally, HRMA was performed on A/H1N1pdm09 and A/H3N2 influenza viruses following BXA selection in vitro. The presence of the I38T mutation in the BXA-selected A/H3N2 variant, but not in the A/H1N1pdm09 variant, was identified by HRMA after 12 passages. Overall, these findings indicate that HRMA could be a powerful tool for rapidly monitoring BXM resistance in influenza viruses during seasonal circulation.

Trypsin digestion of the GII.6 norovirus (NoV) major capsid protein VP1 promotes its binding to histo-blood group antigens (HBGAs), which are believed to be co-receptors for NoVs. In our previous study, we found that trypsin digestion led to the disassembly of GII.6 NoV virus-like particles (VLPs). In this study, we investigated the effect of trypsin digestion on the integrity of GII.6 NoV VLPs using a modified purification approach and determined the N- and C-terminal residues of the fragments produced by digestion, using peptide mass fingerprinting. We also characterized the antigenic epitopes that were affected by trypsin digestion using monoclonal antibodies (mAbs). Our results indicated that GII.6 VLPs remained intact even after complete cleavage at the P1-1/P2 junction. Most of the mAbs in supernatants of hybridoma cell clones showed reduced binding to trypsin-digested GII.6 VLPs. Eight mAbs that showed reduced binding to digested GII.6 VP1 were produced, and these were found primarily to recognize residues located in the P domain. Our results provide evidence of flexibility and extensive morphological changes in the antigenic epitope of GII.6 VLPs after trypsin digestion. It remains to be investigated whether this phenomenon also occurs in virions.

Neurodegenerative pathologies such as age-related macular degeneration currently have no cure or effective treatment. In this type of disease, the presence of amyloid-β peptides, oxidative stress, and inflammation trigger dysregulation of retinal pigment epithelial cells and progression toward the death of these cells, resulting in a loss of vision. The production of amyloid-β peptides, oxidative stress, and inflammation can be triggered in response to viral infections. Fucoidans are sulfated polysaccharides that are present in the cell walls of brown algae. There is a large body of literature reporting a wide range of biological properties of these compounds. In this study, we investigated whether Undaria pinnatifida fucoidan extract can prevent infection with herpes simplex virus type 1 and if the extract has antioxidant activity. We also evaluated whether, under viral infection conditions, the synthesis of amyloid-β peptide and NF-κB activation could be inhibited by the extract. The results showed for the first time that this extract can prevent viral infection in retinal pigment epithelial cells and that they can prevent the formation of amyloid-β peptide and the activation of the NF-κB pathway during viral infection. We also found that Undaria pinnatifida fucoidan extract has antioxidant activity and reduces the levels of reactive oxygen species. These data suggest that Undaria pinnatifida fucoidan extract might be effective for treating diseases triggered by viral infections, such as degenerative retinal diseases.

Most members of the genus Orthonairovirus, represented by Crimean-Congo hemorrhagic fever virus and Nairobi sheep disease virus, are tick-borne, and some have become a public health concern in recent years. Here, we report the isolation and genetic and biological characterization of a new orthonairovirus, designated as "Iwanai Valley virus" (IWVV), from Ixodes ovatus ticks in Hokkaido, Japan. The amino acid sequence of the viral nucleoprotein (NP) was found to be 34–45% identical to those of known orthonairoviruses. Phylogenetic analysis based on amino acid sequences of the viral NP revealed that IWVV is closely related to human-pathogenic tick-borne orthonairoviruses, including Songling virus, Tacheng tick virus 1, and Yezo virus, which were recently discovered in East Asia. BHK-21 (Syrian hamster kidney), Vero (African green monkey kidney), SW-13 (human adrenal adenocarcinoma), HuH-7 (human hepatocellular carcinoma), and ISE6 (Ixodes scapularis tick embryo) cells were found to be susceptible to IWVV infection. Notably, several human-derived cell lines supported efficient replication of the virus. Our findings provide new insights into the diversity, evolutionary dynamics, and geographical distribution of orthonairoviruses in East Asia.

Porcine epidemic diarrhea (PED) caused by porcine epidemic diarrhea virus (PEDV) is a highly contagious and devastating enteric disease of pigs characterized by diarrhea, dehydration and 80-100% mortality in piglets, leading to substantial economic losses in the global swine industry. To investigate the prevalence of PEDV in Henan and Shaanxi provinces of China from 2022 to 2023, a total of 87 clinical samples (including intestinal tissues and faeces) were collected from diseased piglets during outbreaks of diarrhea on pig farms. Of the 87 samples, 32 (36.7%) tested positive for PEDV by RT-PCR, and the complete S gene from nine positive samples and the ORF3 gene from 11 positive samples, all from different farms, were subsequently sequenced. Phylogenetic analysis based on S gene sequences showed that most of the nine PEDV isolates sequenced belonged to the G2a clade and were most closely related to variant strains of PEDV. However, two strains from Shaanxi (CH-SX1-2023 and CH-SX2-2023) belonged to the G2b subtype, and one strain from Henan (CH-HNC2-2023) belonged to the S-INDEL branch. Amino acid sequence comparisons showed that there were several amino acid substitutions and deletions in the S and ORF3 proteins of the PEDV strains from Henan and Shaanxi compared to the CV777 vaccine strain. Some of these mutations occurred in neutralizing epitopes, particularly COE and might therefore be associated with the ineffective protection provided by existing vaccines. These results will provide insights for better understanding of the epidemiological situation of PEDV in Henan and Shaanxi provinces between 2022 and 2023, and this information also contributes to the development of new strategies for the prevention and control of variant PEDV strains.

Classical swine fever (CSF) is endemic in Cuba and is one of the major health problems of the Cuban swine industry. The current efforts to control the disease in Cuba include vaccination with Porvac^®, a subunit marker vaccine. Although the efficacy of Porvac against CSF virus (CSFV) subgenotype 1.4 has been extensively documented, little is known about the ability of the antibodies induced by this vaccine to neutralize other CSFV genotypes. In this study, sera collected from three pigs vaccinated with Porvac were able to efficiently neutralize CSFV strains belonging to genotypes 1, 2, and 3. The findings from this study indicate that additional in vivo studies are warranted to confirm the ability of this vaccine to protect pigs against CSFV genotypes 2 and 3.