Dr. Paul Gerber, 64, a microbiologist who was an official in the Food and Drug Administration's bureau of biologics, died Nov. 27 at George Washington University Hospital after surgery for a heart ailment.

Dr. Gerber came to Washington in 1958 and joined the staff of the National Institutes of Health as a research microbiologist. He remained there until 1972, when he transferred to the FDA and became chief of the viral genetics branch in the bureau of biologics.

Dr. Gerber was recognized for his studies on the EB virus, the organism causing infectious mononucleosis.

Dr. Gerber was a native of Vienna, Austria, and came to this country in 1939. He lived in the Chicago area and was a research scientist with the Squibb drug company in New Jersy before moving to this area. He lived in Silver Spring.

He earned a bachelor's, master's and a doctoral degrees in microbiology at the University of Chicago. He served with the Army in Europe during World War II.

Dr. Gerber's first wife, Edith, died in 1976.

Survivors include his wife, Nina, of Silver Spring; a daughter, Tina Gerber, of Denver, Col., and a son, Martin Gerber, of Washington, both by his first marriage.