I have developed two avidin-biotin alkaline phosphatase stains for West Nile virus in tissues that are formalin fixed and paraffin embedded. One uses a polyclonal and the other a monoclonal (7H2) antibody. Both work fine in positive control chicken embryo heart tissue. I have had difficulty in finding antigen in West Nile infected brain tissues collected one year ago even though there is severe encephalitis present. It is possible that the tissue was collected too late in disease. It was 10-14 days post exposure. However, I am concerned that the negative results may be due to the age of the tissues in paraffin rather than having been collected too late in the disease. I have a good retrieval method and the tests are very reliable on acute cases that are formalin fixed for up to one month and paraffin embedded.
Has anyone done any retrospective studies on paraffin blocks of West Nile virus infected tissues as old as a year or more.If so, did they stain? Also, I would very much like to find a paraffin block that is one year old for a control. A crow heart would be a good choice. I am sure there must be labs out there that have done testing of crows or other animals found dead and submitted for testing. I would like to try my staining on one that was collected a year ago. If it stains, then it is not likely due to the age of the tissues in paraffin. Help would be most appreciated if anyone can spare an old paraffin block of a known case. Douglas Gregg DVM PhD Veterinary Pathologist Southold, NY _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet