Chris Mok and his team worked on the development of the immune response in COVID-19 patients in collaboration with Dr Jincun Zhao from the State Key Laboratory of Respiratory Disease of Guangzhou Medical University. During their research, they found that even mild cases have a robust, neutralizing antibody response.
As of late July, the World Health Organization (WHO) has reported more than 15 Million cases of COVID-19 worldwide, including more than 640,000 deaths, and still little is known about the kinetics, tissue distribution, cross-reactivity and neutralization antibody response to SARS-COV-2.
In this publication, in order to monitor viral shedding and antibody responses in patients with severe and mild disease in different tissues, the authors recruited two groups of RT-PCR confirmed COVID-19 patients, including 12 severe patients in ICUs who needed mechanical ventilation and 11 mild patients in isolation wards.
They found that COVID-19 patients with different severity of disease showed different patterns of viral shedding and antibody responses. Severe patients had more prolonged viral shedding in a variety of tissues than mildly ill patients. SARS-CoV-2-specific antibodies were found in tissues outside the respiratory tract in severe patients. Detection of antibody responses in urine and other body fluids could be used as a marker to determine disease severity.
Interestingly, by using plasma from SARS, MERS and COVID-19 patients, strong cross-reactivities were detected between SARS-CoV-2 and SARS-CoV, but not MERS-CoV which is an important information for differential diagnosis in Middle East countries. More importantly, antibodies against N or S protein were correlated with neutralizing antibody titers which may be useful when screening convalescent plasma for passive transfusion therapy. In summary, this study provides comprehensive information on kinetics, tissue distribution, cross-reactivities and neutralization of antibody responses in COVID-19 patients, and will improve our understanding of humoral immune response in human after SARS-CoV-2 infection as well as shedding light on diagnosis, prognosis, convalescent plasma transfusion therapy and epidemiology studies of SARS-CoV-2 infection in human.
Their findings are published by the Journal of Clinical Investigation: