Virus isolation is expensive and time consuming, and, as most cats with antibody are also viraemic, laboratory diagnosis of infection is generally by antibody detection. Occasionally, however, virus isolation may be necessary to demonstrate infection, for example in very recently infected cats or terminally ill with no detectable antibody.
One or more millilitres of blood are collected in heparin and diluted with cell culture or transport medium. Lymphocytes and monocytes are isolated by centrifugation, and incubated in culture medium, initially with a mitogen of cat T-cells, concanavalin A (con A), to stimulate the lymphocytes divide. After 2~3 days, the cells are washed and resuspended in culture as before, but without con A, and usually with interleukin 2 added. stimulated, uninfected lymphocytes and media are added every 10 days and the culture is tested for FIV production approximately every week for 6 or more weeks by looking for cytopathic effects, by electron microscopy assays for reverse transcriptase or virus antigen production.
Other detection methods, such as polymerase chain reaction and ELISAs, are used experimentally but are not generally available commercially.
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