Howard Temin and David Baltimore independently discover the enzyme reverse transcriptase in RNA viruses. Reverse transcriptase uses RNA as a template to synthesize a single-stranded DNA complement. This process establishes a pathway for genetic information flow from RNA to DNA. With Dulbecco, Baltimore and Temin are awarded the Nobel Prize in Medicine or Physiology in 1975.

Stanley Cohen, Annie Chang, Robert Helling and Herbert Boyer show that extrachromosomal bits of DNA called plasmids act as vectors for maintaining cloned genes in bacteria. They show that if DNA is broken into fragments and combined with plasmid DNA, such recombinant DNA molecules will reproduce if inserted into bacterial cells. The discovery is a major breakthrough for genetic engineering, allowing for such advances as gene cloning and the modification of genes.

Georg Kohler and Cesar Milstein physically fuse mouse lymphocytes with neoplastic mouse plasma cells to yield hybrid cells called hybridomas that can produce specific antibodies and survive indefinitely in tissue culture. This approach offers a limitless supply of monoclonal antibodies. Monoclonal antibodies permit the generation of diagnostic tests that are highly specific. They also function as probes to study cell function. With Jerne, Kohler and Milstein are awarded the Nobel Prize in Medicine or Physiology in 1984.

Carl Woese uses ribosomal RNA analysis to recognize a third form of life, the Archaea, whose genetic makeup is distinct from but related to both Bacteria and Eucarya.

Walter Gilbert and Fred Sanger independently develop methods to determine the exact sequence of DNA. Gilbert uses the technique to determine the sequence of the operon of a bacterial genome. Sanger and colleagues use the technique to determine the sequence of all 5,375 nucleotides of the bacteriophage phi-X174, the first complete determination of the genome of an organism. With Paul Berg, Gilbert and Sanger are awarded the Nobel Prize in Chemistry in 1980.

Smallpox (variola) is declared officially eliminated, the last naturally occurring case having been seen in 1977 in Somalia. Small quantities remain held under tightly controlled conditions in the U.S. and former U.S.S.R. Smallpox is the only microbial disease to ever have been deliberately eradicated.

Stanley Prusiner finds evidence that disease can be caused by a class of infectious proteins he call prions. These abnormal proteins cause scrapie, a fatal neurodegenerative disease of sheep. Prusiner is awarded the Nobel Prize in Medicine or Physiology in 1997.

Luc Montagnier and Robert Gallo announce their discovery of the immunodeficiency virus (HIV) believed to cause AIDS.

Kary Mullis uses a heat stable enzyme from Thermus aquaticus to establish polymerase chain reaction technology. PCR is used to amplify target DNA many-fold. Mullis is awarded the Nobel Prize in Chemistry in 1993.

Craig Venter, Hamilton Smith, Claire Fraser and colleagues at TIGR elucidate the first complete genome sequence of a microorganism: Haemophilus influenza.