Publications by authors named "Akatsuki Saito"
Bovine viral diarrhea (BVD), caused by bovine viral diarrhea virus (BVDV), has a significant economic impact on affected farms worldwide. For effective disease control, it is crucial to select an appropriate vaccine based on the specific genotype of BVDV. Therefore, developing a rapid and reliable assay to detect and genotype BVDV is imperative for controlling the spread of disease.
View Article and Find Full Text PDFUnderstanding the origin and evolution of mutations in SARS-CoV-2 variants of concern (VOCs) is a critical area of research. B. Cao, X.
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- The text discusses how certain viruses can cause persistent infections in various animals, including horses and pigs, leading to significant economic losses due to severe diseases.
- It explains that these viruses have evolved proteins, like glycoprotein 5 (GP5), to evade the host's immune response by inhibiting type I interferon (IFN) signaling.
- The study reveals that 47 GP5 proteins from different hosts can block IFN-β signaling through degradation of TRIF proteins, underscoring the role of GP5 in promoting persistent infections.
Article Synopsis
- Intracellular bacteria like Edwardsiella can thrive inside macrophages, but the specific immune responses and evasion tactics of these pathogens are not well understood.
- Researchers created transgenic Japanese medaka fish with fluorescent macrophages using the mpeg1.1 gene to enhance the study of these immune cells.
- Validation studies showed that the fluorescent macrophages displayed the right characteristics and actively phagocytized the bacteria, setting the stage for future research on how macrophages respond to bacterial infections.
Article Synopsis
- - The XBB sub-variants FL.1 and GE.1 of SARS-CoV-2 are spreading globally, raising concerns about their ability to evade the immune system due to mutations in the spike protein.
- - A study evaluated eleven FDA-approved monoclonal antibody combinations against various Omicron variants, revealing that Sotrovimab was the most effective against XBB.1.5 but less so against the newer sub-lineages FL.1 and GE.1.
- - The results highlight a stronger immune evasion ability in these emerging XBB variants, stressing the importance of ongoing surveillance for novel SARS-CoV-2 variants.
Article Synopsis
- Chronic hepatitis can be caused by hepatitis B virus (HBV) X protein, which helps the virus evade the human immune system and maintain long-term infections.
- This study examined 17 different X proteins from various animals to see if they also inhibit interferon (IFN) signaling.
- The findings showed that many X proteins, including one from domestic cat hepadnavirus, effectively disrupt critical pathways for producing IFN, suggesting a common pattern of immune evasion across species.
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- Mammalian cells use restriction factors and sensors to defend against viral infections, activating the immune system to combat invaders like HIV-1.* -
- ZCCHC3 is a newly identified restriction factor that reduces the production of HIV-1 and other retroviruses without being directly attacked by viral proteins.* -
- It works by binding to key viral components, preventing genome recruitment and leading to less viral replication, making it a potential target for new treatments.*
Article Synopsis
- The emergence of a new Variant of Interest, XBB.1.5, is linked to mutations from the pre-existing variant XBB.1, specifically an S486P spike mutation and a nonsense mutation in ORF8.
- Phylogenetic analysis indicates that XBB.1.5 maintains similar immune escape abilities compared to XBB.1, and structural studies reveal that the spike proteins of both variants are largely similar.
- Research involving hamsters shows that the ORF8 nonsense mutation in XBB.1.5 reduces MHC suppression and results in lower virulence in this variant compared to XBB.1.
Article Synopsis
- In late 2023, the SARS-CoV-2 BA.2.86 variant emerged alongside the dominant XBB descendants like EG.5.1, distinguishing itself with over 30 mutations in its spike protein.
- Modeling showed BA.2.86 has a higher reproduction number compared to EG.5.1, suggesting it spreads more easily.
- Despite its increased spread, BA.2.86 demonstrated lower pathogenicity and replication capacity in hamsters, indicating it may be less severe, while remaining sensitive to four existing antiviral treatments.
Pigs are important animals for meat production but can carry several zoonotic diseases, including the Japanese encephalitis virus, Nipah virus, and influenza viruses. Several and respiratory viruses require cleavage of envelope proteins to acquire viral infectivity and consequently, need a host protease or the addition of exogenous trypsin for efficient propagation. Host TMPRSS2 is a key protease responsible for viral cleavage.
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- * Research in Thailand has shown that two genotypes of DENV2, Cosmopolitan and Asian-I, co-exist, and studies have investigated whether these genotypes differ in their ability to replicate and cause disease.
- * Findings indicate that the Cosmopolitan genotype's structural proteins and non-structural proteins lead to larger viral replication and higher infection rates, suggesting these genetic differences impact the severity of dengue infections.
Article Synopsis
- Pigs serve as important hosts for zoonotic viruses, and the PK-15 cell line derived from pigs is crucial for researching viral diseases and developing vaccines.
- Contamination by type I interferons or IFN-inducing substances can hinder the effectiveness of viral isolation in clinical samples.
- The study successfully created modified PK-15 cells lacking specific interferon receptors, which showed resilience against interferon effects, making them valuable for isolating viruses and advancing vaccine production.
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- Domestic cat hepadnavirus (DCH) is a newly identified infection in cats that resembles human hepatitis B, first spotted in Australia in 2018, and its presence in Taiwan was investigated in this study.
- The research tested 71 cat samples and found 11.27% were positive for DCH, with some positive cats showing signs of chronic hepatitis through elevated liver enzyme levels.
- Genetic analysis revealed distinct viral sequences in the Taiwanese samples, emphasizing the need for ongoing monitoring of DCH and further studies on its causes and spread.
Article Synopsis
- Most research on SARS-CoV-2 variants has concentrated on mutations in spike proteins that influence how the virus infects and spreads.
- This study highlights that there are also significant mutations outside of the spike protein that can affect the virus's behavior.
- Specifically, the study found that certain mutations in the Omicron BA.2 variant, including one in the spike protein and another further down the gene, play crucial roles in defining its characteristics.
Article Synopsis
- The Omicron variant of SARS-CoV-2 evolves to evade immunity from vaccines and prior infections, leading to the emergence of subvariants that escape current antibody treatments.
- An engineered ACE2 decoy shows effectiveness in neutralizing various Omicron subvariants and does not lead to the development of viral escape mutants.
- Inhalation of aerosolized ACE2 decoys has proven beneficial in rodent models and macaques, suggesting this method could enhance COVID-19 treatment efficacy without invasive procedures.
Article Synopsis
- The Orthohepadnavirus genus includes hepatitis B virus (HBV), which can lead to chronic hepatitis and liver cancer in humans, and a newly discovered cat virus, domestic cat hepadnavirus (DCH), which is genetically similar to HBV.
- DCH infection causes chronic hepatitis in cats, indicating that studying DCH could provide insights into HBV's behavior and potentially aid in HBV research.
- The study found that DCH may use similar cell entry mechanisms as HBV, including binding to human and cat NTCP receptors, and identified species-specific binding characteristics, suggesting a risk of transmission between species.
Article Synopsis
- In late 2022, the SARS-CoV-2 Omicron subvariant XBB emerged from the recombination of two existing BA.2 lineages, BJ.1 and BM.1.1.1, during the summer of 2022.
- XBB.1 shows strong resistance to vaccines designed for BA.2/5 and has increased fusogenicity, meaning it can fuse with human cells more efficiently due to changes in its spike protein.
- Research indicates that while XBB.1 is pathogenic, its disease-causing potential in male hamsters is similar to or lower than that of the BA.2.75 variant, marking a notable adaptation in virus evolution through recombination.
Article Synopsis
- In late 2022, several Omicron subvariants emerged globally, characterized by specific amino acid changes in their spike proteins, indicating convergent evolution.
- The study highlights a problematic lineage, BQ.1.1, which shows higher viral fitness due to five critical amino acid substitutions and better evasion of immune responses compared to the BA.5 subvariant.
- In tests on hamsters, BQ.1.1 demonstrated lower pathogenicity than BA.5, revealing insights into the evolutionary patterns of Omicron subvariants up to 2022.
Article Synopsis
- Domestic cat hepadnavirus (DCH) is a new virus discovered in 2018, detected using traditional PCR techniques that are slow and complex.
- A new real-time PCR (rtPCR) method was developed for faster and more accurate DCH detection, using blood samples directly without the need for DNA extraction.
- The assay was designed with specific primers, achieving high sensitivity and making it a valuable tool for monitoring and detecting DCH in cats.
Reliable disinfection and sterilization technologies are needed to deal with the various infectious diseases spreading around the world. Furthermore, bacteria that are difficult to eliminate by ordinary disinfection are also a problem in the medical environment. We examined the germicidal effect of a newly developed deep-ultraviolet light-emitting diode (DUV-LED) prototype device (wavelength of 280 ± 5 nm; power of 0.
View Article and Find Full Text PDFRecent studies have revealed the unique virological characteristics of Omicron, particularly those of its spike protein, such as less cleavage efficacy in cells, reduced ACE2 binding affinity, and poor fusogenicity. However, it remains unclear which mutation(s) determine these three virological characteristics of Omicron spike. Here, we show that these characteristics of the Omicron spike protein are determined by its receptor-binding domain.
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- Zika virus outbreaks in 2015-2016 in Central and South America were major public health issues, ultimately contained through mosquito control and potential herd immunity.
- Research on a cynomolgus monkey model showed that repeated mucosal infection with ZIKV did not lead to viremia or symptoms, but all subjects developed strong neutralizing antibodies.
- These findings suggest that infection at mucosal sites can create protective immunity without widespread viral spread or health complications.
Article Synopsis
- - The SARS-CoV-2 spike protein plays a crucial role in allowing the virus to enter target cells by facilitating membrane fusion.
- - A new assay using a dual functional split reporter protein has been developed to quantitatively study the fusion process in living cells, enabling real-time monitoring.
- - This method can be applied to different cell types and may help predict how harmful new variants of the virus could be, with further details available in the referenced studies.
Virological characteristics of the SARS-CoV-2 Omicron BA.2.75 variant.
Cell Host Microbe
November 2022
Article Synopsis
- The SARS-CoV-2 Omicron BA.2.75 variant, emerging in May 2022, is a distinct descendant of BA.2 and shows a greater reproductive number than the dominant BA.5 variant.
- BA.2.75 demonstrates different responses to vaccines and antibodies, retaining antiviral drug effectiveness but showing variable antibody sensitivity due to unique genetic changes.
- This variant has enhanced ability to bind to human receptors, increased growth efficiency in lung cells, and heightened pathogenicity in hamsters, indicating a potentially greater risk to global health compared to BA.5.