Detection of the Aleutian mink disease virus DNA and antiviral antibodies in experimentally infected mink 10 days post-inoculation

Abstract

Black (n=44) and sapphire (n=12) mink were injected intraperitoneally with 10% spleen homogenates containing a local strain of the Aleutian mink disease virus (AMDV). Animals were euthanized 10 days post-inoculation (pi) and samples of blood and seven organs were collected. Viral DNA was extracted from blood plasma and cell-free organ homogenates (25% W/V) by magnetic beads and tested by PCR. Anti-viral antibodies in blood plasma were tested by counterimmunoelectrophoresis (CIEP). The virus was present in the spleen, lymph nodes, bone marrow and lung samples of all inoculated mink, but was not detected in some intestine (1.9%), kidney (10.7%) and liver (35.7%) samples. Viral DNA was detected in plasma of all inoculated mink by PCR, although two of the samples showed inconclusive test results. Antiviral antibodies were detected in plasma of three sapphire (25.0%) and 19 black (43.2%) mink. The relative specificity and sensitivity of the CIEP test on plasma samples were 100% and 39.3%, respectively, implying that low levels of antibodies during early stages of infection resulted in false negative CIEP tests. Histopathology revealed some lesions characteristics of AMDV infection in the liver and/or kidneys of three black and one sapphire mink, but heart and lung tissues had no detectible lesions. The results suggested that PCR was more reliable than CIEP for viral detection in the early period after infection, and that there were considerable differences among mink of each color type for production of detectable levels of anti-viral antibodies and development of disease symptoms. Samples of saliva, rectal swabs and feces collected on day 10 pi did not produce consistent and reliable results for viral detection by PCR.