$11 million NIH grant awarded for five-year investigation of novel oral chlamydia vaccine

The study of a novel oral vaccine that could protect against chlamydia infection received more than $11 million in National Institutes of Health funding through a five-year U01 grant in April 2024.

"We are excited about receiving the U01 award because it will enable us to move our basic microbiology and immunology bench research work closer to developing a medically significant reagent for making human lives better, our institution's overall mission," said Guangming Zhong, MD, PhD, professor of Microbiology, Immunology and Molecular Genetics with the Joe R. and Teresa Lozano Long School of Medicine at The University of Texas Health Science Center at San Antonio.

Zhong said this vaccine, called intrOv, came about after several years of persistent effort studying chlamydial pathogenic mechanisms in mice.

While investigating mouse-adapted chlamydia, the team accidentally

found that genital chlamydia that spread to the gastrointestinal tract established long-standing colonization.

From there, they tried an oral inoculation of chlamydia to the GI system and found that it became not only non-pathogenic, but also offered protective immunity against subsequent infection in other tissues including the genital tract and airways.

This surprising finding, Zhong said, led them to conclude that an oral delivery of chlamydia could serve as a vaccination against the infection.

The team then created mutant versions of the infection that could no longer cause disease but could induce transmucosal protection.

One of these attenuated mutants, intrOv, included unique qualities viable for cross-species translation to the human pathogen of chlamydia.

"Since the human pathogen chlamydia has more than 15 serotypes, developing a vaccine against all 15 serotypes is challenging. Using the mouse-adapted, chlamydia-based vaccine intrOv to cover all 15 serotypes is a nice surprise," Zhong said.

This grant supports the production of investigative new drug-enabling data for moving the oral chlamydia vaccine to phase 1 trials.

"We will optimize the immunization regimens, identify protection immune correlates in mouse models and validate the vaccine efficacy in pigs and non-human primates," Zhong said.

If all goes well at that stage, the team will file an investigational new drug application with the Food and Drug Administration to advance the vaccine to clinical trials by the end of the grant's timeframe.

In 2022, the health science center was granted an exclusive global license to allow Ohio biopharmaceutical company Blue Water Vaccines Inc. to develop Zhong's findings into an oral vaccine for chlamydia.

Other study collaborators from the Long School of Medicine's microbiology, immunology and molecular genetics department include Zhenming "Jack" Xu, PhD, and Nu Zhang, PhD, who will provide B cell and T cell expertise.

Collaborators for the study include Pat Frost, DVM, and Marie-Claire Gauduin, PhD, primate genital-tract infection experts with Texas Biomedical Research Institute; Yufeng Wang, PhD, bioinformatics expert with The University of Texas at San Antonio; Luis M de la Maza, MD, PhD, with the University of California at Irvine; Huizhou Fan, MD, PhD, with Rutgers University; Harlan Caldwell, PhD, chief of chlamydial diseases section at the National Institute of Allergy and Infectious Diseases; Robert Brunham, MD, with the University of British Columbia; and William Geisler, MD, MPH, from the University of Alabama.

According to the Centers for Disease Control and Prevention, chlamydia is the most reported sexually transmitted infection and affects about 4 million people in the United States each year. The infection is often left untreated due to the lack of specific symptoms. Untreated chlamydial infections can lead to severe complications including pelvic inflammatory disease, infertility and ectopic pregnancy.

There is no vaccine available presently to prevent chlamydia. Vaccines are currently available only for three STIs - HPV, Hepatitis A and Hepatitis B.

The University of Texas Health Science Center at San Antonio (UT Health San Antonio), a primary driver of San Antonio's $44.1 billion health care and biosciences sector, is the largest academic research institution in South Texas with an annual research portfolio of $360 million. Driving substantial economic impact with its six professional schools, a diverse workforce of 7,900, an annual operating budget of $1.08 billion and clinical practices that provide 2.6 million patient visits each year, UT Health San Antonio plans to add more than 1,500 higher-wage jobs over the next five years to serve San Antonio, Bexar County and South Texas. To learn about the many ways "We make lives better®," visit UTHealthSA.org.

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