Taxonomy and Biological Properties
Pathogens belong to the large family Picornaviridae and the genus Enterovirus. Their genetic material is represented by an RNA molecule. A key feature of this group is their tremendous antigenic diversity: over 100 different serotypes have been identified to date. This exact fact is the main reason why people frequently contract colds—immunity to one serotype does not protect against infection by another.
Epidemiology and Transmission
The natural entry portals for the infection are the mucous membranes of the nose, oral cavity, and the conjunctiva of the eyes. The pathogen spreads through the population via two main routes:
- Airborne (droplet) — via sneezing, coughing, and talking.
- Contact (including fomites) — via contaminated hands and household objects.
Pathogenesis
The primary pathology caused by these agents is acute respiratory viral infection (ARVI), predominantly affecting the upper respiratory tract.
The virus uses specific receptor-mediated binding to penetrate the host cell. The target is intercellular adhesion molecule 1, known as ICAM-1. This molecule is located on the surface of various cells in the body, including epithelial cells, fibroblasts, and endothelial cells. By binding to ICAM-1, the viral particle initiates the internalization process and begins its replication cycle.
Microbiological Diagnosis
In routine practice, precise identification of the cold pathogen is rarely required, but two main approaches are used for laboratory confirmation:
- Virological method. Involves isolating the pathogen in specialized cell cultures. Subsequently, the presence of viral antigen is confirmed using the immunofluorescence assay (IFA).
- Serological method. Based on assessing the patient's immune response. Paired acute and convalescent sera are examined in a neutralization test (NT) to evaluate the rise in specific antibody titers.