Abstract: The invention provides a method for generating and identifying antibodies directed against a B7 antigen having SEQ ID NO. 8 or a fragment of SEQ ID NO. 8, which antibodies inhibit B cells from binding CD28, comprising immunizing an animal with the B7 antigen so as to produce the antibodies; and screening the antibodies for antibodies that bind B7 and inhibit CD28 binding to B cells.

Abstract: A method for producing in vivo packaged recombinant adenovirus vectors is provided. The recombinant Ad vectors do not contain any Adenovirus genes and are therefore useful for gene therapy. The recombinant Adenovirus vectors are packaged in vivo using a helper virus which is itself very inefficiently packaged, providing a recombinant viral preparation with very little or no contamination with helper virus. In particular, the method makes use of a helper virus in which the packaging site can be easily excised in vivo by recombination mediated by a recombinase. The helper virus is also useful for the in vivo construction of new recombinant adenovirus vectors containing substitutions in the E1 or other adenoviral region.