The emerging infection of COVID–19 was initiated from Wuhan, China, have been spread to more than 210 countries around the globe including India. The clinical symptoms of COVID–19 are very similar to other respiratory viruses.
The number of laboratory-confirmed cases and associated deaths are increasing regularly in various parts of the World. Seven coronaviruses (229E, NL63, OC43, HKU1, SARS, MERS and, COVID–19) can naturally infect human beings. Out of these four (229E-CoV, NL63-CoV, OC43-CoV, HKU1-CoV) are responsible for mild upper respiratory infections, while SARS-CoV, MERS-CoV, and COVID–19 are well known for their high mortality.
Few mild strains of coronaviruses are circulating in India but there is no evidence of SARS and MERS outbreaks. The COVID–19 is an emerging viral infection responsible for pandemics. Fortunately, the mortality of COVID–19 is low as compared with SARS and MERS, the majority of its cases are recovered.
The death toll of COVID–19 is high even after its low mortality because COVID–19 causes a pandemic while SARS-CoV and MERS-CoV cause epidemics only.
COVID–19 influenced the large segments of the world population, which led to a public health emergency of international concern, putting all health organizations on high alert. COVID–19 is the first coronavirus after Spanish Flu 1918-1919, who has extremely influenced the health system, economy, and psychology of India.
The present study review is on the general continent, virology, pathogenesis, global epidemiology, clinical presentation, diagnosis, treatment and control of COVID–19 with the reference to India.
CoViD–19 Immunopathology and Immunotherapy.
New evidence on the T-cell immuno-pathology in patient’s with Corona Virus Disease 2019 (CoViD–19) was reported by Diao et al. in MedRxiv (doi: 10.1101/2020.02.18.20024364) . It reports observations on 522 patients with confirmed CoViD–19 symptomatology, compared to 40 control subjects.
In brief, notable T cytopoenia was recorded by flow cytometry in the CD4+ and the CD8+ populations, which were significantly yet inversely correlated with remarkably increased serum levels of the pro-inflammatory cytokines IL-6, IL-10 and TNF-a. Flow cytometry established a progressive increase in the expression of programmed cell death marker-1 (PD-1) and T cell immunoglobulin and mucin domain 3 (Tim-3) as patients (n=14) deteriorated from prodromal to symptomatic CoViD–19 requiring intensive care.
Here, we interpret these observations of Diao et al from our current understanding of T cell immunophysiology and immunopathology following an immune challenge in the form of sustained viral infection, as is the case in CoViD–19, with emphasis on exhausted T cells (Tex).
Recent clinical trials to rescue Tex show promising outcomes. The relevance of these interventions for the prevention and treatment of CoViD–19 is discussed. Taken together, the data of Diao et al could proffer the first glimpse of immunopathology and possible immunotherapy for patients with CoViD–19.