Features of immunopathogenesis of a new coronavirus infection

The main biological characteristics of viruses of the Coronaviridae family are presented. The features of the immunopathogenesis of these infections are analyzed. It was found that the structural proteins of the spine, membrane, envelope and nucleocapsid play an important role in the immunopathogenesis of COVID-19 infection. They are associated with hyperactivation of neutrophils and monocytes-macrophages, secreting large amounts of pro-inflammatory cytokines and chemokines. This contributes to the development of a «cytokine storm» and an unfavorable prognosis of the disease. A particularly high risk of developing pneumonia exists against the background of an increase in the production of: macrophage inflammatory protein-1 alpha, macrophage chemotactic protein, interleukin 8. At the height of infection in some patients, macrophages and dendritic cells infected with SARS-CoV-2 lose their ability to produce type I interferons and pro-inflammatory cytokines. On the part of cellular immunity, a significant decrease in the number of CD4⁺ and CD8⁺-lymphocytes was noted. Among IgG sub-isotypes, IgG3 antibodies had the highest reactivity, and IgG1 antibodies were less reactive. Antibodies to spike protein with low specificity or low titer do not neutralize the virus and contribute to the contamination of immunocompetent cells via Fc receptors. Low-affinity antibodies or their low levels can contribute to increased cell sensitivity to SARS-CoV-2 and the development of severe forms of COVID-19 disease.