ALEUTIAN DISEASE OF MINK: SERODIAGNOSIS AND SEROEPIDEMIOLOGY

The experiments described in this thesis were undertaken to investigate the potential of the enzyme linked immunosorbent assay (ELISA) as an experimental and serodiagnostic technique for the detection of antibody to Aleutian disease virus (ADV) in the serum of infected mink.; The optimal pH for the reaction of anti-ADV antibody and viral antigen in the ELISA was pH 8.0. Antibody binding activity in the ELISA was greatly reduced at pH 7.4. The optimal antigen concentration for use in the ELISA was eight times less than the concentration required for counterimmunoelectrophoresis (CIEP).; The immunological sensitivity of the ELISA was at least 80 times greater than CIEP when compared under experimental conditions. The ability of the ELISA to detect anti-viral antibody in the serum of mink in the first week of infection with ADV was comparable to the detection of antibody by CIEP. Antibodies of the IgG and IgM classes were detectable simultaneously by the ELISA in the first week of infection.; After experimental infection with a high dose of virus to produce progressive Aleutian disease (P-AD), IgG and IgM ELISA titers increased exponentially. Maximal titers were detected two to three weeks after infection and then sharply declined to low levels by seven weeks. ELISA titers remained stable but low for the duration of the 29 week experiment. Anti-viral antibody titers, measured by CIEP, increased exponentially and peak titers were attained five to seven weeks after infection. CIEP titers remained stable and high for the duration of the experiment.; When mink with natural, non-progressive Aleutian disease (NP-AD) were tested by ELISA, no anti-viral antibody activity could be demonstrated in either the IgG or IgM class. Precipitating antibody was detectable by CIEP in these mink.; The macromolecular fraction (Sephacryl S300) of serum from normal mink, from mink with NP-AD and from mink in late stages of experimental P-AD caused inhibition in the ELISA of anti-ADV antibody activity in high ELISA titered serum from mink in early stages of P-AD. This inhibitory effect may account for the sudden decrease in serum ELISA titers observed seven weeks after experimental infection and may also be responsible for the inability to detect antibody activity in the ELISA of serum from mink with NP-AD.; The ELISA, by itself, was not suitable as a diagnostic screening test due to its inability to detect mink with NP-AD. Using CIEP as an indicator of infection, the ELISA was effective in differentiating mink with NP-AD from mink with P-AD. The combined use of the ELISA and CIEP could be beneficial in determining the prevalance and distribution of NP-AD and P-AD in ranch mink.