Relative infectivity of the SARS-CoV-2 Omicron variant in human alveolar cells

With the emergence of multiple highly transmissible SARS-CoV-2 variants during the recent pandemic, the comparison of their infectivity has become a substantially critical issue for public health. However, a direct assessment of these viral characteristics has been challenging due to the lack of appropriate experimental models and efficient methods. Here, we integrated human alveolar organoids and single-cell transcriptome sequencing techniques to facilitate the evaluation. In a proof-of-concept study using the assay with four highly transmissible SARS-CoV-2 variants, including GR (B.1.1.119), Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (BA.1), a rapid evaluation of the relative infectivity was possible. Our results demonstrate that the Omicron (BA.1) variant is 3-5-fold more infectious to human alveolar cells than the other SARS-CoV-2 variants at the early phase of infection. To our knowledge, this study provides the first direct measurement of the infectivity of the Omicron variant and new experimental procedures that can be applied for monitoring newly emerging viral variants.

The in vitro and in vivo potency of CT-P59 against Delta and its associated variants of SARS-CoV-2

The Delta variant originally from India is rapidly spreading across the world and causes to resurge infections of SARS-CoV-2. We previously reported that CT-P59 presented its in vivo potency against Beta and Gamma variants, despite its reduced activity in cell experiments. Yet, it remains uncertain to exert the antiviral effect of CT-P59 on the Delta and its associated variants (L452R). To tackle this question, we carried out cell tests and animal study. CT-P59 showed reduced antiviral activity but enabled neutralization against Delta, Epsilon, and Kappa variants in cells. In line with in vitro results, the mouse challenge experiment with the Delta variant substantiated in vivo potency of CT-P59 showing symptom remission and virus abrogation in the respiratory tract. Collectively, cell and animal studies showed that CT-P59 is effective against the Delta variant infection, hinting that CT-P59 has therapeutic potency for patients infected with Delta and its associated variants. HighlightsO_LICT-P59 exerts the antiviral effect on authentic Delta, Epsilon and Kappa variants in cell-based experiments. C_LIO_LICT-P59 showed neutralizing potency against variants including Delta, Epsilon, Kappa, L452R, T478K and P681H pseudovirus variants. C_LIO_LIThe administration of clinically relevant dose of CT-P59 showed in vivo C_LIO_LIprotection against Delta variants in animal challenge experiment. C_LI

Diverse Effects of Small Molecule Inhibitors on Actin Cytoskeleton Dynamics in HIV-1 Infection

The dynamics of the actin cytoskeleton plays a pivotal role in the process of cell division, the transportation of organelles, vesicle trafficking and cell movement. Human immunodeficiency virus type 1 (HIV-1) hijacks the actin dynamics network during the viral entry and migration of the pre-integration complex (PIC) into the nucleus. Actin dynamics linked to HIV-1 has emerged as a potent therapeutic target against HIV infection. Although some inhibitors have been intensely analyzed with regard to HIV-1 infection, their effects are sometimes disputed and the exact mechanisms for actin dynamics in HIV infection have not been well elucidated. In this study, the small molecules regulating HIV-1 infection from diverse inhibitors of the actin dynamic network were screened. Two compounds, including Chaetoglobosin A and CK-548, were observed to specifically bar the viral infection, while the cytochalasin family, 187-1, N-WASP inhibitor, Rho GTPase family inhibitors (EHop-016, CID44216842, and ML-141) and LIMK inhibitor (LIM domain kinase inhibitor) increased the viral infection without cytotoxicity within a range of ~ µM. However, previously known inhibitory compounds of HIV-1 infection, such as Latrunculin A, Jasplakinolide, Wiskostatin and Swinholide A, exhibited either an inhibitory effect on HIV-1 infection combined with severe cytotoxicity or showed no effects. Our data indicate that Chaetoglobosin A and CK-548 have considerable potential for development as new therapeutic drugs for the treatment of HIV infection. In addition, the newly identified roles of Cytochalasins and some inhibitors of Rho GTPase and LIMK may provide fundamental knowledge for understanding the complicated actin dynamic pathway when infected by HIV-1. Remarkably, the newly defined action modes of the inhibitors may be helpful in developing potent anti-HIV drugs that target the actin network, which are required for HIV infection.

Immunodeficiency Virus Type 1 Infection of H9 Cells

Human immunodeficiency virus type 1 (HIV-1) virus causes severe defect in the immune system and affects the host cell gene expression profoundly. The gene expression pattern will be characterized by changes in cellular mRNA levels that are dependent on both the stage of infection and the biological state of the infected cells. The expression levels of 7,404 cellular RNA transcripts were assessed in H9 cells at different time points after HIV-1 IIIB infection. In total 7 time-points, 959/7,404 (13%) genes were a 2-fold or greater expressed. 387 of 959 genes (40.4%) were up-regulated, and other 572 genes (59.6%) were down-regulated. Three hundred seventeen genes were up-regulated a 2-fold or greater at 72 hr postinfection and 2 to 139 genes were up-regulated at the other time-points. In contrast, 126 to 349 genes were down-regulated a 2-fold or greater in all time-points, excepting 6 hr postinfection. Twenty-three genes were up-regulated a 2-fold or greater over at least four of seven time-points, which were mostly ribosomal proteins and MHCs. Especially, MHCs including HLA-DRA were steadily up-regulated from 24 hr postinfection. Thirty genes were down-regulated a 2-fold or greater in all the time-points, which were mainly related with synthesis and metabolism. These results show that host cell gene expression was altered by HIV-1 infection according to time-points and will provide a framework for studies on interactions between host and HIV-1 infection.