Yellow fever is a mosquito-borne viral infection with no known treatment that affects some 200,000 people each year in Africa and South America. The disease has been surging in recent years, including an epidemic in Brazil in 2017-19 that was the largest outbreak in 70 years. Current yellow fever vaccines are based on a virulent African strain of the virus and considered to be equally effective against all yellow fever variants, including the emerging Brazilian strain.

In a study published online on January 7 in Cell Host & Microbe, an international team of researchers led by Kartik Chandran, Ph.D., and research fellow Denise Haslwanter, Ph.D., at Albert Einstein College of Medicine report that the human antibody response induced by the widely used yellow fever vaccine has reduced activity against the recent Brazilian strain.

Using standard blood tests for measuring antibody responses, the authors found that changes in the envelope protein—the main target for neutralizing antibodies—in the Brazilian strain of the virus makes it more resistant to the antibodies elicited by the vaccine—similar to the ongoing situation with COVID-19’s Omicron variant. By identifying the key amino acid changes that have made the Brazilian strain less susceptible to vaccine-induced neutralization, the research provides a roadmap to improve assessments of the YFV antibody response in South American vaccines and for developing next-generation yellow fever vaccines.

Dr. Chandran is professor of microbiology & immunology and the Harold and Muriel Block Faculty Scholar in Virology at Einstein.

Additional Einstein authors include: Gorka Lasso, PhD., Alexandra Tse, Yan Sun, Ph.D., Stephanie Stransky, Ph.D., and Simone Sidoli, Ph.D. Other institutions participating in this project were: Fundação Oswaldo Cruz (Fiocruz), Brazil; Adimab, LLC; Universidade de São Paulo, Brazil; The George Washington University; and Mapp Biopharmaceutical, Inc. Myrna Bonaldo, Ph.D., (Fiocruz) is a co-senior author with Dr. Chandran.