Abstract <p>Correlation constants are the values of quantity for relationships between the structural components of the immune system. Changes in magnitude and vector directions of these values indicate instability of immune functions to cause disease emerging. The objective of the research study is to estimate the immune-parameter (NLR and IgG/IgM) constitution constants used as immunogenic biomarkers in experimental infection of sheep with the bovine leukemia virus. The sheep serum immunoglobulin level was determined with the single radial immunodiffusion technique and the poly- and monoclonal antibody-based assay for IgM and IgG, while the relative neutrophil lymphocyte counts were measured with the standard methods. To assess the relationship between the values, the Pearson correlation coefficient was used. Correlation strength was assessed with the Chaddock scale. A correlation between the neutrophil and lymphocyte counts tended to remain negative at all the test stages, although its values had the pattern of instability. A decrease in the strength of a correlation between the neutrophil and lymphocyte rates was revealed only on day 3 after the infection event and to 7 months of immunogenesis, which might be associated with increasing the neutrophil counts and emerging bacterial complications. IgG/IgM constitution constant tended to change from day 1 of the immune response. Significant reduction in the correlation strength occurred in the period from day 7 to day 14 after immunization. The unstable dynamic pattern for the relationship between the early and late immunoglobulins shows the pathogen that blocks the synthesis of antiviral and neutralizing antibodies, which may cause the appearance of infection-induced immunopathology. However, the capacity of the adaptive immune system is preserved at the strong negative correlation between neutrophil and lymphocyte counts, (<i>r</i> = –0.9). That is exactly the priority correlation constant for the viral infection rate. The research outcomes showed the prospects for the use of constitution constants as biomarkers for different phases of immunogenesis.</p>