Mink persistently infected with Aleutian disease virus (ADV) develop plasmacytosis (hypergammaglobulinaemia) and
immune complex disease. Mink of different colour phases were infected with different strains of ADV and bled at different times after
infection. The average antibody affinities (Kav) were measured in the sera and found to fall in the range of 2 X 10(9) - 2 X 10(10) M-1, thus indicating good-quality
antibodies. In sera of non-Aleutian genotype mink a decline in Kav during development of plasmacytosis was observed. Moreover, the antibody heterogeneity (alpha values) tended to decrease during the disease progress. In contrast, the Kav values in sera of infected Aleutian genotype mink remained relatively high after hypergammaglobulinaemia developed, and the antibody heterogeneity for certain of the mink sera indicated restricted heterogeneity (high alpha values). In agreement with the clonal selection theory, low virus burden (for instance, during
infection with a low-virulence ADV strain) generated relatively higher affinity
antibodies than a high virus burden for instance, the highly virulent Utah I strain of ADV). Furthermore,
antibodies present in low concentration were of higher affinity than
antibodies present in high concentrations. The relatively high affinity
antibodies found in this study indicate that if the
immune complex disease seen in AD is caused by virus-anti-virus
antibodies, good-quality
antibodies are likely to be responsible for the pathological findings.