井戸 栄治

Numerous SARS-CoV-2 variant strains with altered characteristics have emerged since the onset of the COVID-19 pandemic. Remdesivir (RDV), a ribonucleotide analogue inhibitor of viral RNA polymerase, has become a valuable therapeutic agent. However, immunosuppressed hosts may respond inadequately to RDV and develop chronic persistent infections. A patient with respiratory failure caused by interstitial pneumonia, who had undergone transplantation of the left lung, developed COVID-19 caused by Omicron BA.5 strain with persistent chronic viral shedding, showing viral fusogenicity. Genome-wide sequencing analyses revealed the occurrence of several viral mutations after RDV treatment, followed by dynamic changes in the viral populations. The C799F mutation in nsp12 was found to play a pivotal role in conferring RDV resistance, preventing RDV-triphosphate from entering the active site of RNA-dependent RNA polymerase. The occurrence of diverse mutations is a characteristic of SARS-CoV-2, which mutates frequently. Herein, we describe the clinical case of an immunosuppressed host in whom inadequate treatment resulted in highly diverse SARS-CoV-2 mutations that threatened the patient's health due to the development of drug-resistant variants.

BACKGROUND/AIM: Sindbis virus (SINV) is a naturally occurring oncolytic virus that kills cancer cells and is less harmful to normal cells. In this study, a recombinant SINV, which expressed green and blue fluorescent proteins, was used to precisely analyze SINV infection and replication. MATERIALS AND METHODS: Antiviral responses, including IFN-β mRNA, protein kinase R (PKR), NF-B, and caspase 3/7, were analyzed in SINV-infected cancerous HeLa cells and normal human fibroblast TIG-1-20 cells. RESULTS: SINV could infect, replicate, and proliferate both in HeLa and TIG-1-20 cells, causing lytic infection only in HeLa cells. SINV grew preferentially in HeLa cells causing remarkable apoptosis. IFN-β mRNA expression was suppressed in SINV-infected HeLa cells compared to that in TIG-1-20 cells. Further analyses of PKR and NF-B upstream of IFN-β induction revealed that the compromised response in the PKR-NF-B pathway during early infection coincided with IFN induction suppression in HeLa cells. CONCLUSION: Dysregulation of PKR in HeLa cells is the determinant of SINV oncolysis.

The aim of this study was to establish and apply a real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) for human immunodeficiency virus (HIV) RNA quantification in patients on antiretroviral treatment (ART) in Ghana, where recombinant strains including CRF02_AG are prevalent. The primers and TaqMan probe concentrations as well as reaction temperatures were optimized to establish an efficient in-house quantitative assay system for HIV RNA, a tool for HIV viral load measurement in patients. Then an already established HIV-specific PCR amplicon (HIV-1 NL4-3) was used as an external standard to estimate the linearity, amplification efficiency, analytical sensitivity and reproducibility of the in-house real time quantitative assay. Finally, the assay was applied to quantify the viral load in clinical samples of HIV patients on ART. The real time quantitative assay was shown to have good linearity (R2=1.0), high amplification efficiency (E=1.91), high sensitivity (180 copies/ml), and high reproducibility (variation coefficient range, from 1.25% to 3.58%). Analytical specificity and sensitivity of the assay in clinical samples was 96.7% and 95.0%, respectively. The established tool is reliable and covers all relevant genotypes including rare and recombinant forms that circulate in the sub-region. It could therefore allow general monitoring of antiretroviral therapy in patients living in resource-limited settings due to its simplicity, rapidity and less-labour intensiveness. © 2014 Barnor JS, et al.