Publications by authors named "Calvin Duong"
SARS-CoV-2 has gradually acquired amino acid substitutions in its S protein that reduce the potency of neutralizing antibodies, leading to decreased vaccine efficacy. Here, we attempted to obtain mutant viruses by passaging SARS-CoV-2 in the presence of plasma samples from convalescent patients or vaccinees to determine which amino acid substitutions affect the antigenicity of SARS-CoV-2. Several amino acid substitutions in the S2 region, as well as the N-terminal domain (NTD) and receptor-binding domain (RBD), affected the neutralization potency of plasma samples collected from vaccinees, indicating that amino acid substitutions in the S2 region as well as those in the NTD and RBD affect neutralization by vaccine-induced antibodies.
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- SARS-CoV-2 has been circulating in humans since 2019 and has been reported in at least 32 animal species, including dogs and cats, which are particularly vulnerable to the virus.
- A study developed an ELISA test to measure the prevalence of SARS-CoV-2 antibodies in dogs and cats by analyzing serum samples collected during two periods: early in the pandemic (May-June 2020) and mid-pandemic (October 2021 - January 2022).
- Results showed low seroprevalence, with only a few samples testing positive for antibodies, indicating that dogs and cats in Japan are not a significant reservoir for SARS-CoV-2.
The influenza A(H1N1)pdm09 virus that emerged in 2009 causes seasonal epidemic worldwide. The virus acquired several amino acid substitutions that were responsible for antigenic drift until the 2018-2019 influenza season. Viruses possessing mutations in the NA and PA proteins that cause reduced susceptibility to NA inhibitors and baloxavir marboxil, respectively, have been detected after antiviral treatment, albeit infrequently.
View Article and Find Full Text PDFJapan has reported a relatively small number of COVID-19 cases. Because not all infected persons receive diagnostic tests for COVID-19, the reported number must be lower than the actual number of infections. We assessed SARS-CoV-2 seroprevalence by analyzing >60,000 samples collected in Japan (Tokyo Metropolitan Area and Hokkaido Prefecture) during February 2020-March 2022.
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- The emergence of the Omicron variant BA.2 has heightened worries about the reduced effectiveness of current COVID-19 vaccines and treatments due to its mutations, with BA.2 now dominant in many countries.
- Research comparing the infectivity and pathogenicity of BA.2 to BA.1 in mice and hamsters found that both variants exhibit similar levels of infectivity but are less pathogenic than earlier SARS-CoV-2 strains.
- Despite a significant decrease in neutralizing antibody response from COVID-19 survivors and vaccine recipients against BA.2, some therapeutic monoclonal antibodies and antiviral drugs still show effectiveness in treating BA.2 infections in hamsters.
Objective Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread globally. Although the relationship between anti-SARS-CoV-2 immunoglobulin G (IgG) antibodies and COVID-19 severity has been reported, information is lacking regarding the seropositivity of patients with particular types of diseases, including hematological diseases. Methods In this single-center, retrospective study, we compared SARS-CoV-2 IgG positivity between patients with hematological diseases and those with non-hematological diseases.
View Article and Find Full Text PDFThe recent emergence of SARS-CoV-2 Omicron variants possessing large numbers of mutations has raised concerns of decreased effectiveness of current vaccines, therapeutic monoclonal antibodies, and antiviral drugs for COVID-19 against these variants1,2. While the original Omicron lineage, BA.1, has become dominant in many countries, BA.
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