The gene frequencies and haplotypic associations within the HLA region have been investigated in 916 unrelated Japanese individuals. HLA class I and class II antigens were studied by conventional serology, and class II alleles, DRB1, DRB3, DQA1, DQB1 and DPB1 were typed by using polymerase-chain reaction amplification and sequence-specific oligonucleotide probe (PCR-SSOP) method. Thirty DRB1, 3 DRB3, 8 DQA1, 15 DQB1 and 13 DPB1 alleles were found in our population. DR-NJ25, a characteristic antigen in the native American and Asian populations, was observed at 3.0%. This antigen was observed mainly with the DRB1*1403 and 1406 alleles. Twenty-seven out of 30 DRB1 alleles found in this study had a high positive linkage disequilibrium with DQB1 alleles and 20 of them had an exclusive association with one specific DQA1-DQB1 combination. The strong association between DRB1 alleles and HLA-B antigens was the most striking finding in this study. Twenty-eight out of 30 DRB1 alleles had a positive linkage disequilibrium with 24 HLA-B antigens (p < 0.01). The other two alleles, DRB1*0404 and 1402, were very rare, and their frequencies were 0.2% and 0.1%, respectively. The data presented in this population study should be useful for the studies on anthropology, organ transplantation and disease susceptibility.

Coronavirus disease 2019 (COVID-19) has caused serious public health, social, and economic damage worldwide and effective drugs that prevent or cure COVID-19 are urgently needed. Approved drugs including Hydroxychloroquine, Remdesivir or Interferon were reported to inhibit the infection or propagation of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), however, their clinical efficacies have not yet been well demonstrated. To identify drugs with higher antiviral potency, we screened approved anti-parasitic/anti-protozoal drugs and identified an anti-malarial drug, Mefloquine, which showed the highest anti-SARS-CoV-2 activity among the tested compounds. Mefloquine showed higher anti-SARS-CoV-2 activity than Hydroxychloroquine in VeroE6/TMPRSS2 and Calu-3 cells, with IC50 = 1.28 μM, IC90 = 2.31 μM, and IC99 = 4.39 μM in VeroE6/TMPRSS2 cells. Mefloquine inhibited viral entry after viral attachment to the target cell. Combined treatment with Mefloquine and Nelfinavir, a replication inhibitor, showed synergistic antiviral activity. Our mathematical modeling based on the drug concentration in the lung predicted that Mefloquine administration at a standard treatment dosage could decline viral dynamics in patients, reduce cumulative viral load to 7% and shorten the time until virus elimination by 6.1 days. These data cumulatively underscore Mefloquine as an anti-SARS-CoV-2 entry inhibitor.

The development of effective antiviral drugs targeting the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) is urgently needed to combat the coronavirus disease 2019 (COVID-19). We have previously studied the use of semi-synthetic derivatives of oxysterols, oxidized derivatives of cholesterol as drug candidates for the inhibition of cancer, fibrosis, and bone regeneration. In this study, we screened a panel of naturally occurring and semi-synthetic oxysterols for anti-SARS-CoV-2 activity using a cell culture infection assay. We show that the natural oxysterols, 7-ketocholesterol, 22(R)-hydroxycholesterol, 24(S)-hydroxycholesterol, and 27-hydroxycholesterol, substantially inhibited SARS-CoV-2 propagation in cultured cells. Among semi-synthetic oxysterols, Oxy210 and Oxy232 displayed more robust anti-SARS-CoV-2 activities, reducing viral replication more than 90% at 10 μM and 99% at 15 μM, respectively. When orally administered in mice, peak plasma concentrations of Oxy210 fell into a therapeutically relevant range (19 μM), based on the dose-dependent curve for antiviral activity in our cell-based assay. Mechanistic studies suggest that Oxy210 reduced replication of SARS-CoV-2 by disrupting the formation of double-membrane vesicles (DMVs); intracellular membrane compartments associated with viral replication. Our study warrants further evaluation of Oxy210 and Oxy232 as a safe and reliable oral medication, which could help protect vulnerable populations with increased risk of developing COVID-19.