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d-Opioid receptor (DOR) is an oxygen-sensitive protein whose function in the rat retina is unknown. We examined whether DOR is involved in hypoxic preconditioning (HPC)-mediated retinoprotection following intraocular pressure (IOP) elevation. Rats were exposed to intermittent hypoxia (10% oxygen) to induce HPC. Unilateral retinal ischemia/reperfusion injury was induced by elevating IOP to 100 mmHg for 1 h. HPC attenuated the loss of neuronal marker expression and increased pro-apoptotic caspase 3 activity in the IOP retina. Excess superoxide production and 8-iso-prostaglandin F2a accumulation caused by enhanced oxidant protein expression and reduced antioxidant enzyme level after IOP elevation were largely abrogated by HPC. HPC markedly increased the expression of hypoxia-inducible factor-1a (HIF-1a) and DOR, but intravitreal administration of HIF-1a-specific small interfering RNA abrogated the up-regulation of DOR. This suggested that DOR functions downstream of HIF-1a. However, the endogenous content of leucine enkephalin in retinas was not affected by HPC or IOP. Treatment of retinas with the DOR antagonist naltrindole attenuated the HPC-induced protection and activation of extracellular signal-regulated kinase. These results suggest a novel mechanism of HPCmediated retinoprotection whereby HIF-1a induces the expression of DOR, and DOR-mediated activation of extracellular signal-regulated kinase triggers cellular events that correct the redox imbalance in the post-ischemic retina.

SARS-CoV-2 Spike-specific antibodies contribute the majority of the neutralizing activity in most convalescent human sera. Two SARS-CoV-2 variants, N501Y.V1 (also known as B.1.1.7 lineage or VOC-202012/01) and N501Y.V2 (B.1.351 lineage), reported from the United Kingdom and South Africa, contain several mutations in the receptor binding domain of Spike and are of particular concern. To address the infectivity and neutralization escape phenotypes potentially caused by these mutations, we used SARS-CoV-2 pseudovirus system to compare the viral infectivity, as well as the neutralization activities of convalescent sera and monoclonal antibodies (mAbs) against SARS-CoV-2 variants. Our results showed that N501Y Variant 1 and Variant 2 increase viral infectivity compared to the reference strain (wild-type, WT) in vitro. At 8 months after symptom onset, 17 serum samples of 20 participants (85%) retaining titers of ID50 >40 against WT pseudovirus, whereas the NAb titers of 8 samples (40%) and 18 samples (90%) decreased below the threshold against N501Y.V1 and N501Y.V2, respectively. In addition, both N501Y Variant 1 and Variant 2 reduced neutralization sensitivity to most (6/8) mAbs tested, while N501Y.V2 even abrogated neutralizing activity of two mAbs. Taken together the results suggest that N501Y.V1 and N501Y.V2 reduce neutralization sensitivity to some convalescent sera and mAbs.

The currently used vaccine against tuberculosis, Bacille Calmette‐Guérin (BCG), has variable efficacy, so new vaccine development is crucial. In this study, we evaluated a recombinant vaccine prepared from non‐pathogenic Mycobacterium smegmatis (rMS) that expresses a fusion of early secreted antigenic target 6‐kDa antigen (ESAT6) and culture filtrate protein 10 (CFP10). C57BL/6 mice were immunized with the rMS expressing the ESAT6‐CFP10 fusion protein (rM.S‐e6c10) or with BCG. The mice in the rM.S‐e6c10 group had a significantly higher titre of anti‐ESAT6‐CFP10 antibodies than did animals in the BCG or saline groups. Spleen cells from rM.S‐e6c10‐immunized mice exhibited a cytotoxic response to ESAT6 and CFP10‐expressed target cells, but spleen cells from animals in the other groups did not. Levels of IFN‐γ and IL‐2 production by purified T cells from spleens were significantly higher in rM.S‐e6c10 group than in BCG group. Finally, after M. tuberculosis (MTB)‐challenged mice, dramatic reduction in the numbers of MTB colony‐forming units (CFUs) in the lungs was observed for the mice immunized with the rMS. The protective efficacy of rM.S‐e6c10 and BCG vaccination was similar based on measures of MTB burden and lung pathology. Our data indicate that the recombinant M. smegmatis vaccine expressing the ESAT6‐CFP10 fusion protein has potential in clinic application.