Studies on the Nature of Hemophilus Influenzae Cells Susceptible to Heritable Changes by Desoxyribonucleic Acids* by Hattie E. Alexander, M.d., Grace Leidy, and Eros Hahn

There is now convincing evidence that highly specific desoxyribonucleic acids (DNA's) can direct some inherited traits of members of 3 different bacterial species, Diplicoccus pneumoniae (1), Hemophilus influenzae (2, 3), and Neisseria rnenlngitidis (4), and suggestive evidence that heritable traits of certain viruses, rabbit fibroma (5), and bacterial viruses (6), may be influenced by the action of DNA. The new virus particles produced by Hirst (7) through the interaction of 2 different antigenic types of influenza A viruses may result from a process comparable to those processes producing allogenic transformation of pneumococci by Ephrussi-Taylor (8) and type Sab H. influenzae cells (9) produced by the interaction of type a H. influenzae DNA on type b H. influenzae cells. Earlier findings (2, 9, 10) have demonstrated 8 different "heredity determinants" in DNA-containing preparations, which can induce highly specific heritable changes with predictable regularity in H. influenzae populations (Table I). DNA has been shown to be an essential component of each; desoxyribonuclease (DNAse) destroys the activity which induces heritable changes. Six of the 8 heredity determinants control the type-specific traits, a, b, c, d, e, a n d f (2). One controls streptomycin (SM) resistance (10) and one induces the Sab trait (9). Two different purification procedures (3, 11), applied to crude DNA extracts of type b and type c H. influenzae by Zamenhof et al., have yielded DNA fractions of a high degree of purity, biologically active in a concentration as low as 3 X 10 -~ ug. per nil. The action of the DNA which is essential for inducing a heritable change is virtually immediate if transformable ceils are present (2). A medium which supports growth is not needed for the action of DNA. The reaction can occur in a simple environment, such as unenriched broth containing no x and v factors which are required for growth of H. influenzae. These characteristic features of the DNA action could be demonstrated whether the "recipient population" (population exposed to the DNA) is made up of "R" (non-encapsulated)