SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion

https://www.nature.com/articles/s41423-020-0424-9

studies have shown that SARS-like viral particles and SARS-CoV RNA were detected in T lymphocytes isolated from peripheral blood sample, spleen, lymph nodes, and lymphoid tissue of various organs,22

, 23 suggesting that SARS-CoV might be able to infect T cells directly.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30920-X/fulltext

Elderly and middle-age patients had significantly higher plasma NAb titers (P<0.0001) and spike-binding antibodies (P=0.0003) than young patients. Notably, among these patients, there were ten patients whose NAb titers were under the detectable level of our assay (ID50: < 40); while in contrast, two patients, showed very high titers of NAb,

Crystal structure of SARS-CoV-2 main protease provides a basis for design of improved α-ketoamide inhibitors

https://science.sciencemag.org/content/368/6489/409.full

Contact 1 also was positive for SARS-CoV-2 on qRT-PCR tests of multiple serial throat swab specimens but negative for SARS-CoV-2 on IgM and IgG tests.

All 5 household contacts of patient 1 had laboratory evidence of SARS-CoV-2 infection but remained asymptomatic throughout the period of observation (February 11–March 1) (Figure, panel A). All household contacts who had throat swab specimens tested for SARS-CoV-2 were positive by PCR except for contact 2, who tested negative on 4 consecutive throat swab specimen tests for SARS-CoV-2 but whose stool specimen was positive for SARS-CoV-2; contact 2 also had elevated liver enzymes but no jaundice. Contact 3 had an elevated D-dimer level. These abnormal laboratory values resolved during observation (Table) and were not associated with clinical illness in either patient. Patient 1 and contacts 2 and 4 also had abnormal chest computed tomography scans consistent with SARS-CoV-2 infection

Contact 1 underwent 11 serial throat swabs for SARS-CoV-2. Her case demonstrates the challenges of clinical interpretation qRT-PCR results for SARS-CoV-2. On 2 separate occasions, she had 2 consecutive negative results on throat swab specimens for SARS-CoV-2, only to revert back to having a throat swab specimen positive for SARS-CoV-2 (Figure, panel A). Contact 1 was the only family member who underwent serologic tests, which demonstrated low B lymphocyte counts but no detectable SARS-CoV-2–specific IgM or IgG. We cannot determine the cause or clinical significance of the lack of a detectable antibody response in contact 1 in our study