A new comprehensive study conducted by researchers at New York University College of Dentistry (NYU Dentistry) in collaboration with Rheonix Inc. describes a novel test for Zika virus, which utilizes saliva for rapid identification of the diagnostic markers of the virus.
Credit: Tacio Philip Sansonovski/ Shutterstock.com
The test was a modified version of an existing model developed by the researchers at NYU and Rheonix for rapid HIV testing, which has appeared in two publications, PLOS ONE and the Journal of Visualized Experiments (JoVE).
Factors including population concentration and global air travel account for the frequent outbreak of infectious diseases. The World Health Organization declared Zika and related birth defects a public health crisis after the 2015 outbreak of the virus in Brazil which spread to other countries in Central and South America, the Caribbean, and the Southern United States.
Dr. Maite Sabalza, the lead author and postdoctoral associate at the Department of Basic Science and Craniofacial Biology at NYU Dentistry said: "The recent Zika virus outbreak confirms that we need an effective surveillance and diagnostic program to reduce the impact of future emerging infectious diseases."
Early detection of the pathogens is crucial for preventing the outbreak of the diseases, which involves two separate steps: one to detect a pathogen's nucleic acids (RNA or DNA) and another to test for antibodies– the proteins the body produces in response to pathogens.
Conventional testing methods involve blood samples to detect the Zika virus and are typically processed using a common diagnostic technique called real-time polymerase chain reaction (RT-PCR). However, blood may not be the best fluid as the virus may disappear in the blood within a week or two following infection.
In addition, it can persist longer in semen, saliva, and urine as the antibodies could prevail for months or years in such bodily fluids, thereby making it essential for diagnosis to also detect antibodies after infection.
Current RT-PCR tests require three hours and specific antibody tests can take several weeks. However, the novel method developed the NYU researchers was based on isothermal amplification, which could detect the nucleic acids of a virus within 20 minutes, and perform antibody tests, which utilizes Zika-specific antigens, in less than an hour.
The sooner you can identify a pathogen, the sooner steps can be taken to treat and isolate people. During an epidemic, you could test people before they get on a plane. The future of going through security at the airport may not be taking off your shoes, but instead spitting into a tube."
Dr. Daniel Malamud, NYU Dentistry
Researchers modified the current model so as to use markers which could detect the Zika nucleic acid sequences instead of those for HIV. Further, they used a portable isothermal amplification device– used for point-of-care testing– to detect Zika RNA.
Researchers adapted the test to the Rheonix CARD® cartridge and workstation, allowing them to approximate the viral load in saliva samples in order to understand the severity of the disease and immune responses, especially among pregnant women and fetuses.
The researchers also recognized Zika-specific antigens– which can be used to identify the Zika specific antibodies needed for testing– using a high-density peptide microarray. Since Zika can be easily misdiagnosed with other viruses like chikungunya and dengue, detection of Zika-specific antigens necessitates more precise diagnostic testing.
Researchers at NYU and around the world continue to validate their observations in further experiments using Zika-infected saliva.
Dr. Sabalza said: "In working towards the goal of quickly making effective diagnostics available, we have developed a generic protocol that can not only be used to test for Zika virus but can be adapted for the next emerging or re-emerging infectious disease."
Dr. Richard Montagna, Rheonix's Senior Vice President for Scientific & Clinical Affairs, said: "In addition to being able to react very quickly to any newly emerging or re-emerging infectious disease, our fully automated testing platform requires virtually no hands-on efforts and is well suited for use by individuals with minimal training."