FeLV is suspected in individual cats which have enlarged lymph nodes or are anaemic and wasted. It is commonly the mesenteric nodes which are palpable in early cases although normal kidneys have sometimes been mistaken for enlarged lymph nodes.
FeLV is also suspected in households or breeding catteries, especially Siamese, where there is a history of reproductive failure or deaths in young cats.
Antigen, p27 or envelope protein, not antibody, by sandwich- ELISA Now the true prevalence of UK FeLV antigenaemia is about 1% the number of false positives can also approach that level. Positive ELISA viraemics can be confirmed by virus isolation.
Virus isolation at Glasgow vet school. Plasma from 2-5 ml heparinised blood is adsorbed onto monolayers of cat cell lines which contain integrated sarcoma virus DNA in their nuclei. If the plasma contains FeLV, which causes no cpe, the cells' sarcoma virus is rescued FeLV and causes transformation with rounding up of the cell monolayer.