852
Using a monoclonal antibody , Lt-4 , directed against human T cell leukemia virus type I ( HTLV-I ) trans-activator ( tax1 ) antigen , we examined the expression of tax1 and related antigens in a variety of T cell lines bearing HTLV-I and related retroviruses , simian T cell leukemia virus type I ( STLV-I ) and HTLV-II , by immunofluorescence and immunoblot assays .
 protein: human T cell leukemia virus type I ( HTLV-I ) trans-activator ( tax1 ) antigen; protein: antigens; protein: tax1; protein: monoclonal antibody; protein: Lt-4; protein: human T cell leukemia virus type I ( HTLV-I ) trans-activator; protein: tax1; cell line: T cell lines
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 protein: human T cell leukemia virus type I ( HTLV-I ) trans-activator ( tax1 ) antigen; protein: antigens; protein: tax1; protein: monoclonal antibody; protein: Lt-4; protein: human T cell leukemia virus type I ( HTLV-I ) trans-activator; protein: tax1; cell line: T cell lines