Broad phenotypic alterations and potential dysfunctions of lymphocytes in COVID-19 recovered individuals

BackgroundLymphopenia is a typical symptom in the COVID-19 patients. While millions of patients are clinical recovered, little is known about the immune status of lymphocytes in these individuals. MethodsA clinical recovered cohort (CR) of 55 COVID-19 individuals (discharged from hospital 4 to 11 weeks), and 55 age and sex matched healthy donors cohort (HD) were recruited. Detailed analysis on phenotype of the lymphocytes in peripheral blood mononuclear cells (PBMCs) was performed by flow cytometry. FindingsCompared with cohort HD, the CD8+ T cells in cohort CR had higher Teff and Tem, but lower Tc1 (IFN-{gamma}+), Tc2 (IL-4+) and Tc17 (IL-17A+) frequencies. The CD4+ T cells of CR had decreased frequency, especially on the Tcm subset. Moreover, CD4+ T cells of CR expressed lower PD-1 and had lower frequencies of Th1 (IFN-{gamma}+), Th2 (IL-4+), Th17 (IL-17A+) as well as circulating Tfh (CXCR5+PD-1+). Accordingly, isotype-switched memory B cell (IgM-CD20hi) in CR had significantly lower proportion in B cells, though level of activation marker CD71 elevated. For CD3-HLA-DRlo lymphocytes of CR, besides levels of IFN-{gamma}, Granzyme B and T-bet were lower, the correlation between T-bet and IFN-{gamma} became irrelevant. In addition, taken into account of discharged days, all the lowered function associated phenotypes showed no recovery tendency within whole observation period. InterpretationThe CR COVID-19 individuals still showed remarkable phenotypic alterations in lymphocytes after clinical recovery 4 to 11 weeks. This suggests SARS-CoV-2 infection imprints profoundly on lymphocytes and results in long-lasting potential dysfunctions. FundingKunming Science and Technology Department (2020-1-N-037)

Impaired T cell functions along with elevated activated Tregs at the early stage of asymptomatic SARS-CoV-2 infection

BackgroundLimited data are available on the T cell responses for the asymptomatic SARS-CoV-2 infection case. MethodsAn imported SARS-CoV-2 infection case in Wuhan was admitted in hospital for quarantine and observation. The T cell responses were followed up by flow cytometry analysis of the peripheral blood nonnuclear cells (PBMCs) at days 7, 13, 22, and 28 after admission. FindingsWe found the imported SARS-CoV-2 infection in Wuhan is an asymptomatic case. His T cell differentiation, proliferation and activation matched the classical kinetics of T cell responses induced by viral infection, but the activation maintained at a relatively low level. Function analysis indicated frequencies of IFN-{gamma} producing CD4+ and CD8+ T cells were notably lower than that of the healthy controls (HC) at day 7, and then rebound gradually. But IFN-{gamma}+CD8+ T cells were detained at a significant lower level even at day 28, when the SARS-CoV-2 virus had already become undetectable for 3 weeks. Moreover, percentage of IL-17 producing CD4+ T cells was also detained constantly at a much lower level compared to HC. At day 7, although percentage of Tregs was in normal range, the frequency of activated Treg (aTreg) was remarkably as high as 4{middle dot}4-fold of that in HC. InterpretationThe T cell activation in the asymptomatic SARS-CoV-2 infection experienced a significant suppression and presented impairment of Th1/Th17 and CD8+ T cell functions. Early elevation of the aTregs might play role in the activation and function of T cells in the asymptomatic SARS-CoV-2 infection.

PIKA Provides an Adjuvant Effect to Induce Strong Mucosal and Systemic Humoral Immunity Against SARS-CoV / 中国病毒学·英文版

Severe Acute Respiratory Syndrome(SARS)is a deadly infectious disease caused by SARS Coronavirus(SARS-CoV).Inactivated SARS-CoV has been explored as a vaccine against SARS-CoV.However,safe and potent adjuvants,especially with more efficient and economical needle-free vaccination are always needed more urgently in a pandemic.The development of a safe and effective mucosal adjuvant and vaccine for prevention of emergent infectious diseases such as SARS will be an important advancement.PIKA,a stabilized derivative of Poly(I:C),was previously reported to be safe and potent as adjuvant in mouse models.In the present study,we demonstrated that the intraperitoneal and intranasal co-administration of inactivated SARS-CoV vaccine together with this improved Poly(I:C)derivative induced strong anti-SARS-CoV mucosal and systemic humoral immune responses with neutralizing activity against pseudotyped virus.Although intraperitoneal immunization of inactivated SARS-CoV vaccine alone could induce a certain level of neutralizing activity in serum as well as in mucosal sites,co-administration of inactivated SARS-CoV vaccine with PIKA as adjuvant could induce a much higher neutralizing activity.When intranasal immunization was used,PIKA was obligatorily for inducing neutralizing activity in serum as well as in mucosal sites and was correlated with both mucosal IgA and mucosal IgG response.Overall,PIKA could be a good mucosal adjuvant candidate for inactivated SARS-CoV vaccine for use in possible future pandemic.