William R. Jacobs Jr., is a professor of Microbiology and Immunology and Professor of Genetics at Albert Einstein College of Medicine in The Bronx, New York, where he is also a Howard Hughes Medical Institute Investigator.

[1] His research efforts are aimed at discovering genes associated with virulence and pathogenicity in M. tuberculosis and developing attenuated strains for use as vaccines.

He is a Founding Scientist at the KwaZulu-Natal Research Institute for Tuberculosis and HIV.

[2] In 1985, Jacobs joined Barry Bloom's lab at Albert Einstein College of Medicine as a post-doctoral fellow[3] to work on the resurgent problem of tuberculosis.

In 1987, the two co-authored a ground-breaking[4] paper published in Nature describing a novel system for the genetic manipulation of mycobacteria, "Introduction of Foreign DNA into Mycobacteria Using a Shuttle Phasmid".