New synthetic biomarker technology can distinguish between past Zika and dengue infections

A newly discovered synthetic molecule specific to the Zika virus can distinguish between samples from patients who are immune to the Zika virus and those who have previously been infected with a related dengue virus. Scientists have announced that this technology could lead to the development of better diagnostics and vaccine candidates. Proceedings of the National Academy of Sciences.

The study, led by researchers at the University of Pittsburgh School of Public Health and the Herbert Wertheim College Scripps Institute for Biomedical Innovation and Technology, is the first to apply the innovative “epitope substitution” technology to Zika. .

Until now, researchers and clinicians have lacked diagnostic tools to easily distinguish between past infections with various flaviviruses, such as Zika and dengue, a group of viruses primarily transmitted by mosquitoes and ticks. I did. This poses challenges for clinical epidemiology studies, viral diagnostics, and vaccine development.

“If you go to a place like Brazil, almost everyone will have some degree of immunity to dengue and Zika,” said lead author Dr. Priscilla Castaña, assistant professor in Pitt's Department of Infectious Diseases and Microbiology. public health.

“This makes it extremely difficult to test new treatments or determine the prevalence of new diseases in areas where flaviviruses are endemic, causing a high global disease burden. It has become.”

Antibodies from Zika virus, a mosquito-borne virus that spread to the Americas in 2015 and still causes sporadic illness, can be confused with antibodies from dengue virus in many diagnostic tests and have not previously been tested. It becomes difficult to determine whether a person who tested positive for dengue fever had dengue fever. Zika, or both.

Infection during pregnancy can cause birth defects, so it is important for women of reproductive age to know whether they have already been infected with Zika and whether they are likely to have immunity. Especially important. Knowing whether you have immunity may determine how much effort you make to avoid mosquitoes in endemic areas during pregnancy.

Using an approach pioneered by co-senior author Thomas Kodadek, Ph.D., a chemist at the Scripps Research Institute at Wertheim University, the research team tested 500,000 “peptide-inspired structures” on human blood samples. “Picco-Constricted Oligomers” (PICCO) were screened. infected with dengue fever or Zika virus.

PICCO is an inorganic molecular shape attached to microscopic plastic beads. These mimic epitopes that are part of the pathogen that antibodies attach to in order to neutralize the threat.

If any of the PICCOs match the corresponding shape of an antibody in a blood sample, the antibody latches on to them, allowing researchers to “fish out” it. The presence of antibodies against a virus in someone's blood means they have been previously infected with the virus or have been vaccinated, prompting their immune system to produce antibodies.

“This technology is amazing; you don't need to know the sequence, structure, or even the pathogen,” said co-senior author Donald Burke, M.D., dean emeritus of the Pitt School of Public Health.

“As long as we choose the right set of patient blood samples to compare, we can uncover important antibodies and corresponding synthetic molecular biomarkers that differ between patient sets.”

Researchers identified 40 PICCOs with Zika virus antibodies. Screening blood positive for dengue, one of her PICCOs, called CZV1-1, was particularly good at hooking Zika antibodies, but not for dengue. This single CZV1-1 PICCO synthetic molecule accurately identified people who had been infected with the Zika virus 85.3% of the time and produced false positives in only 1.6% of tests; is equivalent to a COVID-19 antibody test.

Castaña, Burke, and co-senior author Ernesto T. A. Marquez, M.D., Ph.D., associate professor in the Department of Infectious Diseases and Microbiology at Pitt Public Health, have been studying the Zika virus since it emerged in the Americas in 2015. In Brazil, Castaña, Marquez, and Burke were studying the dengue virus.

“For every sample tested during the 2015 outbreak, 10 different blood tests had to be performed to confirm Zika,” Castaña said. “These tests are technically difficult and time-consuming, making them impractical for clinical guidance. If this molecule had been available at the time, it would have been great.”

The diagnostic ability to differentiate flavivirus antibodies is important in clinical epidemiology studies. Marquez and Burke previously showed that for Zika and dengue viruses, patient outcomes differ based on past exposure, posing challenges to prevention, diagnosis, and care.

Importantly, the PICCO screening technology used to identify molecules unique to the Zika virus does not require refrigeration and could be used in other outbreaks.

“This molecule is a molecular mimic and cannot be deployed,” Kodadek said. “This means there is no need for a cold chain, making it particularly useful for outbreaks in remote or low-resource areas.”