PerkinElmer Inc. has agreed to buy BioLegend, a privately held maker of biomedical research tools for Covid-19 and other illnesses, for about $5.25 billion in shares and cash.

The transaction, the largest-ever acquisition for Waltham, Massachusetts-based PerkinElmer, is expected to close by the end of this year, subject to regulatory approvals, the companies said in a statement Monday.

Research tools such as antibodies have become key to the study of Covid as the pandemic has spread around the world , driving PerkinElmer’s shares up almost 70% since the beginning of last year. BioLegend provides antibodies and reagents for biomedical research to laboratories at universities and pharma companies studying cells, proteins and genetics.

With more than 700 employees, mostly in the U.S., the firm is expected to generate sales of about $380 million in 2022, according to the statement. After the purchase, BioLegend’s campus in San Diego will become PerkinElmer’s center of excellence for development of substances used in research analysis, called reagents, and expand its business into new segments, the statement said.

Goldman Sachs Bank USA is providing bridge financing to PerkinElmer for the cash portion of the purchase, which is expected to provide an estimated 30 cents of adjusted earnings per share accretion in the first full year after the close and more than close 50 cents in the second, according to the statement.

Goldman Sachs & Co. is exclusive financial adviser to PerkinElmer for the deal, WilmerHale serving is legal counsel and McDermott Will & Emery is antitrust counsel. J.P. Morgan Securities LLC is BioLegend’s financial advisor, and Pillsbury Winthrop Shaw Pittman LLP is its legal counsel.