![t cell repertoire t cell repertoire](https://i1.rgstatic.net/publication/260219036_T_cell_repertoire_following_autologous_stem_cell_transplantation_for_multiple_sclerosis/links/5a4bd03f458515a6bc6bef5f/largepreview.png)
The antiviral adaptive immunity is greatly dependent on the activation of T-cells, which can selectively eliminate virus-infected host cells ( 20). However, the pathogenesis is not fully understood at present.
![t cell repertoire t cell repertoire](https://els-jbs-prod-cdn.jbs.elsevierhealth.com/cms/attachment/fd9169c8-9780-4efa-b568-c3ecd8aa077a/gr4_lrg.jpg)
We performed a comprehensive analysis of the transcriptomic profiles of PBMCs from COVID-19 patients in our previous studies ( 19). Although most re-detectable positive cases have minor symptoms and hardly disease progression upon readmission, their potential infectivity and immunological characterization remain undefined ( 17, 18). Unlike symptomatic patients who can be effectively identified by clinical features, asymptomatic carriers may inadvertently transmit virus to close contacts and reshape the dynamics of infection in population ( 15, 16). Many previous immunological studies have focused on symptomatic and convalescent patients ( 5– 12), while the immune responses in asymptomatic patients and re-detectable positive cases remain unclear ( 13, 14). The global efforts to end COVID-19 are complicated by the prevalence of asymptomatic and recurrent infection. Moreover, among the COVID-19 convalescent patients, some tested positive again after discharge (i.e., re-detectable positive) ( 4). The clinical manifestations of infected patients ranged from asymptomatic condition to severe symptoms ( 3).
![t cell repertoire t cell repertoire](https://image.slidesharecdn.com/tcellrepertoireselftolerance-100323054405-phpapp02/95/t-cell-repertoire-self-tolerance-29-1024.jpg)
As a highly infectious virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the pandemic of coronavirus disease 2019 (COVID-19) ( 1, 2).