Abstract
In this issue, we have eight original articles describing studies performed in hepatitis B virus (HBV), dengue virus (DENV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The defining characteristics that determine the response to interferon (IFN) treatment in HBV infection remain unclear. Here, Huang et al. describe 36 exosomal-miRNAs in an IFN-sensitive group, and 32 exosomal-miRNAs in an IFN-insensitive group, which might affect response to therapy. The authors propose that targeting exosomal-miRNAs could represent a novel therapeutic option in the context of chronic HBV infection.
Two other articles in this issue focus on DENV infection. In the first, Ruiz-Pacheco et al. explore the role of neutrophils in the development of inflammation in DENV infection. The authors focus on molecules known to regulate neutrophil function during viral infection. They report that DENV2 infection can significantly increase TREM-1 and CD10 expression, as well as TREM-1 production from cultured human neutrophils, suggesting that neutrophil CD10 and TREM-1 might contribute to the pathogenesis of DENV infection.
The second article, by Villanueva-Aguilar et al., attempts to identify gene mutations that might be associated with disease severity in DENV infection. In a cohort including 272 cases of suspected dengue infection, with 102 confirmed cases, the authors found a significantly higher frequency of a TNFA allele in both DENV+ and DENV- groups, with higher representation in the DENV+ group.
Finally, we also have five articles focusing on SARS-CoV-2 and coronavirus disease 2019 (COVID-19). Despite the rapid development of COVID-19 vaccines that significantly reduced disease severity, the major limitation of these vaccines was their short duration of protection from infection due to rapid waning of antibody levels. In this issue, Li et al. investigated the persistence of SARS-CoV-2-specific neutralizing antibodies in convalescent persons from January 2020 to January 2021.
They found that ∼95% of individuals studied maintained neutralization activity for up to 6 months, but that this dropped off to just over 30% by 10 months postinfection. By now, we have seen numerous studies suggesting that hybrid immunity is more effective than immunity generated from natural infection alone. The data presented by Li et al., therefore, highlight the importance of COVID-19 vaccination even after natural infection with SARS-CoV-2.
In a second article on the topic of SARS-CoV-2 antibodies, Kim et al. investigated seroprevalence in individuals living in senior care facilities who experienced breakthrough Omicron infection. The authors report that vulnerability to Omicron breakthrough infection in third-dose elderly individuals was due to low neutralizing antibody levels against the Omicron variant. These findings highlight the existence of a group of “vaccinated vulnerable” individuals within our societies.
In a similar study, Suryawanshi et al. examined lymphopenia and T cell subsets in 139 hospitalized COVID-19 patients in India. It was reported that patients experienced decreased CD3+ T cells, CD4+ T cells, naive and central memory T cells, as well as NK cells. The authors also reported increased levels of effector T and effector memory T cells in patients with severe COVID-19.
In an effort to help understand the differences in immune responses potentially generated by Delta and Omicron variant-specific vaccines, Shahsavandi and Harari describe an elaborate in silico analysis comparing these two variants with respect to B cell and T cell epitopes, Toll-like-receptor biding, RBD/ACE2 interactions, as well as RNA folding and immune response simulation.
Finally, very early in the COVID-19 pandemic, it was hypothesized that pre-existing cross-reactive immunity against other human coronaviruses might be the reason for asymptomatic infection in many individuals. Lobaina et al. specifically addressed this question by testing sera from inactivated vaccine-immunized donors and from vaccinated and subsequently naturally infected (hybrid immunity) donors. Through this analysis, the authors generated interesting findings suggesting that cross-reactive antibodies existed against original SARS-CoV as well as a wider cross-reactivity for the N antigen of human Alpha coronavirus HCoV-229E.
In closing, we wish to thank all authors for their outstanding research contributions, all reviewers for volunteering their time to help ensure the quality of work published in our journal, and of course to all study subjects for providing crucial samples that help us understand the immune responses against these viruses.