The construction of the second-floor addition to James Laboratory was completed in 1961 with the receipt of a $70,000 grant from the NIH. In the newly renovated laboratory, the first floor was transformed into a Drosophila genetics laboratory and the new second floor housed bacterial genetics and biochemistry laboratories. By 1969, with the hiring of Joseph Sambrook and other prominent tumor virologists, James Lab became the center of tumor virus research.

In 1971, another addition was built on the south side of James Laboratory and was called the James Annex. It was a two-story addition housing offices for senior scientists as well as a Director’s office suite and seminar/library room, all with views of the Harbor. Major funding for the addition came serendipitously from John Davenport, a retired Pfizer company executive with an interest in tumor virus research. Another small addition was built on the west (front) side of James in 1973 to house the first laboratories specifically designed for research on animal viruses.