Construction of the recombinant feline herpesvirus type 1 deleted thymidine kinase gene.

We constructed a recombinant virus containing defined deletion within thymidine kinase (TK) gene from feline herpesvirus type 1 (FHV-1) C7301, which was isolated in Japan, by standard rescue procedures with thymidine arabinoside (araT) selection. The araT resistant recombinant virus was designated as C7301dlTK. Southern blot analysis, together with polymerase chain reaction, revealed a deletion with the expected size, based on agarose gel electrophoresis, of the TK gene region in the C7301dlTK. Growth kinetics of the C7301dlTK in CRFK cells was similar to that of ther parent C7301 that possesses TK activity. However, plaques produced by the C7301dlTK were significantly smaller than those of the parent virus. This report migth be applicable for the development of a new genetically engineered FHV-1 vaccine.