The aim: The aim of the study is to experimentally test the process of viral infection and determine the ways of its penetration into the human body. Materials and methods: This experimental analysis is based on systematic research, published peer-reviewed articles, books, textbooks, monographs. It should also be noted that in order to identify some immunocompetent lymph node cells and the ability to visualize certain sites in the lymphoid nodes of Peyer’s patches, where the initial processes are presented below, we resorted to sampling anatomical material. The study involved 10 adult albino rats weighing 200.0 ± 20.0 g. The search period covered the period from 2010 to 2021, but the experimental analysis contains some valuable data from previous years, as these literature sources have significant scientific value. Results: According to immunohistochemical analysis of the epithelium associated with the dome of the lymph nodes of the small intestine of white rats, the bulk was B-lymphocytes (about 47%) and T-lymphocytes (about 35%), while plasma cells, macrophages and dendritic cells accounted for approximately 5% for each of them. Conclusions: Рrocess of development of viral infection can be represented in the form of the following targeted steps: 1) massive invasion of viruses into the body; 2) the pathway of viruses to the intended target (target cells) is carried out by the blood flow; 3) аchieving the target by viruses and their penetration into target cells. Іn the pathogenesis of viral diseases, the role is played by the preparedness of the particular body, which directly depends on the functional state of its immune system, which determines the possibility, severity and outcome of the disease.