RESUMO
The emerging SARS-CoV-2 variants have made great challenges to current vaccine and pandemic control strategies. B.1.1.529 (Omicron), which was classified as a variant of concern (VOC) by the World Health Organization on November 26th, 2021, has quickly become the dominant circulating variant and causing waves of infections. It is urgent to understand the current immune status of the general population given that pre-existing immunity has been established by national vaccination or exposure to past variants. Using sera from 85 individuals (including 21 convalescents of natural infection, 15 cases suffered a breakthrough infection after vaccination, and 49 vaccinated participants without infection history), we showed that the cross-neutralizing activity against VOCs such as Omicron can be detected in 53 (62.4%) cases, although less potent than against the Wuhan-1 strain (WT), with a 3.9-fold reduction in geometric mean neutralizing titer (GMT) (130.7, 95% CI 88.4-193.3 vs 506, 355.8-719.7, respectively). Subgroup analysis revealed significantly enhanced neutralizing activity against WT and VOCs in Delta convalescent sera. The neutralizing antibodies against Omicron were detectable in 75% of convalescents and 44.9% of healthy donors (p = 0.006), with a GMT of 289.5, 180.9-463.3 and 42.6, 31.3-59, respectively. However, the protective effect against VOCs was weaker in young convalescents (aged < 18y), with a detectable rate of 50% and a GMT of 46.4 against Omicron, similar to vaccinees. The pan-sarbecovirus neutralizing activities were not observed in vaccinated SARS-CoV-1 survivors. A booster dose significantly increased the breadth and magnitude of neutralization against WT and VOCs to different degrees than full vaccination. In addition, we showed that COVID-19 inactivated vaccines can elicit Omicron-specific T cell responses. The positive rates of ELISpot reactions were 26.7% (4/15) and 43.8% (7/16) in the full vaccination group and the booster vaccination group, respectively. The neutralizing antibody titers declined while T-cell responses remain robust over 6 months. These findings will inform the optimization of public health vaccination and intervention strategies to protect diverse populations against SARS-CoV-2 variants.
RESUMO
Objective To investigate the effect of triptolide (TP) on the expression of hypoxia inducible factor 1 alpha (HIF1α) and vascular endothelial growth factor (VEGF) in the human umbilical vein endothelial cells (HUVECs) under hypoxia. Methods (1) HUVECs were treated with 0, 40, 80, 160 and 320 nmol/L TP (named with hypoxia group, TP40 group, TP80 group, TP160 group and TP320 group, respectively) under the hypoxic condition (37℃, 5%CO2, 1%O2, 94%N2) for culturing 12 hours. Meanwhile, cells cultured under normoxia condition (without TP added) were set as the normoxia group. Western blot assay was used to detect the expression of HIF1αin each group. (2) The cells were divided into normal control group, hypoxia group and TP80 group. The immunofluorescence method was performed to detect the localization of HIF1α in cells. (3) Expressions of VEGF were detected by Western blot assay in TP80 group and hypoxia group. (4) The cells were divided into hypoxia group, TP80 group, TP80+KF20 group (80 nmol/L TP and 20μmol/L KC7F2), and TP80+KF30 group (80 nmol/L TP and 30 μmol/L KC7F2). After 12-hour culturing, Western blot assay was used to detect the expressions of HIF1α and VEGF in each group. Results (1) Under the normoxia condition, no HIF1α was detected in HUVECs. The expression level of HIF1αwas significantly increased in TP80 group than that in hypoxia group (P<0.05), while there was no significant change in expression of hypoxia HIF1αin TP160 group and TP320 group compared with that of hypoxic group. (2) The immunofluorescence result showed that HIF1α was mainly expressed in the nucleus. (3) The expression of VEGF was significantly increased in TP80 group than that in hypoxia group (P < 0.05). (4) After the intervention of KC7F2, HIF1αand VEGF expression levels were significantly decreased in the TP80+KF20 group and the TP80+KF30 group than those in the TP80 group (P<0.05). Conclusion TP can improve the expression of HIF1αand VEGF to accelerate the proliferation of endothelial cells under hypoxia condition.
