The phrase "a major agent of" is correct and usable in written English.
It can be used to describe something or someone that plays a significant role in a particular process or effect.
Example: "Education is a major agent of social change, influencing the values and behaviors of individuals."
Alternatives: "a key driver of" or "a significant contributor to".
Mrs. Kennedy was a major agent of this change.
Streptococcus pneumoniae is a major agent of severe infections in humans, including meningitis.
However, behavior often shows large phenotypic variation and flexibility, and can be both – subject to selection and a major agent of selection.
Grouped loosely under the heading "the knowledge society" and sometimes "the knowledge economy", they portray the university not just as a creator of knowledge, a trainer of young minds and a transmitter of culture, but also as a major agent of economic growth: the knowledge factory, as it were, at the centre of the knowledge economy.
Taken together, these observations indicate that AdVs is still a major agent of severe pneumonia and it plays an important role in lethal severe pneumonia in Guangzhou area.
In all subhabitats biological sound daily dynamics are a major agent of change, especially in the evening, when fish sounds overwhelm spectra in marine and transition zones.
Shortly after she came to the United States, her father James S.C. Chao founded Foremost Maritime Corporation, which developed trade with Taiwan and was a major agent for shipments of rice during the Vietnam War.
Distributed control of the multi-agent systems involving a major agent and a large number of minor agents is investigated in this paper.
This would strongly evidence that this process is a major agent shaping the intra-population variance of the mouse mandible.
Castells starts out by noting that throughout history, social movements have been major agents of social change; he would say THE major agent of social change.
