Critical factors in an enzyme immunoassay (ELISA) for antibodies to mouse thymic virus (MTLV).

Mouse thymic virus (MTLV; murid herpesvirus 3) is a naturally occurring herpesvirus of mice. Critical variables in an enzyme immunoassay (ELISA) for antibodies to mouse thymic virus (MTLV) were assessed. High protein binding plates proved unsuitable. For storing coated plates, the most consistent results were obtained when coated plates were washed and stored with coating buffer (phosphate buffered saline, PBS) at -70 degrees C. Storage of antigen at -20 degrees C was unsatisfactory, although coated plates could be stored at -20 degrees C for at least 1-2 weeks. In performing the ELISA, vigorous washing and blocking were critical. However, substituting isotonic (0.9%) saline for PBS in washing solutions gave reliable results at considerable cost savings. For blocking, and as sample diluent, a modification of 'BLOTTO' (5% nonfat dry milk and 0.2% Tween 20) was most satisfactory.