George W. Rusten began working at the National Institutes of Health (NIH) in 1941 as a manual laborer while he was waiting for another job to start. As a manual laborer, Rusten performed a variety of tasks including cleaning out offices, cutting grass, digging ditches, and driving trucks. When the other job never opened, what was supposed to be a temporary position turned into a lifelong career at the NIH. In 1942, Rusten had a physical examination for a permanent position as a laborer, but the doctors detected a slight heart murmur and suggested he would need to do lighter work. For a short while he was the elevator operator in Building 5.

Rusten's first laboratory job came in 1943 in the glassware washing room of the Laboratory of Tropical Diseases in the former Microbiological Institute (now the National Institute of Allergy and Infectious Diseases). Rusten had applied for the job of an under-scientific helper, but the job was later reclassified as a junior laboratory assistant.

The next year, 1949, Rusten won an award for superior accomplishment for creating three pieces of equipment that facilitated his laboratory work. The three pieces were an operating block for holding laboratory animals, a rocker that agitates media in an incubator, and an inoculating block that facilitates intravenous inoculation of chickens.

In 1955, when the Division of Biologics Standards (DBS) was established, Rusten became a research technician in the Laboratory of Viral Immunology. The research technician position was normally held by college graduates, but because of Rusten’s strong background in laboratory techniques and his great abilities which had led to multiple promotions, he was able to fill this role without a bachelor’s degree.