Scientists improve diagnostic tool for rapid use during viral outbreaks: study

WASHINGTON, April 26 (Xinhua) -- American scientists reported a new tool that updates a CRISPR-based diagnostic tool for rapid outbreak response unveiled last year, enabling clinicians to quickly diagnose patient samples and track epidemics such as Ebola and Zika with limited equipment.

In a study published on Thursday in the journal Science, researchers at Broad Institute of Massachusetts Institute of Technology (MIT) and Harvard made a platform that can now be used to detect viruses directly in clinical samples such as blood or saliva.

The SHERLOCK diagnostic platform (shorthand for Specific High-sensitivity Enzymatic Reporter unLOCKing) used a programmed enzyme called Cas13 paired with reporter molecules to indicate the presence of a genetic target, such as a virus.

But until now, a crucial preliminary step for SHERLOCK involved extracting and isolating nucleic acids from patient samples, which typically requires a lab and trained personnel.

The research team, led by Harvard graduate student Catherine Freije and postdoctoral scientist Cameron Myhrvold, developed a simpler method that allows Cas13 to detect its target directly in bodily fluid samples such as saliva or blood.

The process is called HUDSON, or Heating Unextracted Diagnostic Samples to Obliterate Nucleases.

It consists of a rapid chemical and heat treatment used on the samples in order to inactivate certain enzymes that would otherwise degrade the genetic targets.

The processed clinical samples can then be run through the SHERLOCK procedure, and the final detection results, positive or negative, can be easily viewed on the paper strips.

The whole pipeline can be completed in under two hours, according to the researchers.

"Rapid and sensitive tools are critical for diagnosing, surveilling, and characterizing an infection," said the paper's senior author Pardis Sabeti, an institute member at Broad and professor at Harvard University.

Sabeti's team is further setting up the ability to test SHERLOCK with collaborators in Nigeria, which suffered an unusual surge in Lassa fever cases this spring. Lassa fever often causes symptoms shared by many viruses, and the mainstay treatment works best if administered early on, so an accurate and rapid diagnosis is critical.

"This system is putting us even closer to a fast and user-friendly diagnostic that can be easily deployed anywhere," said Sabeti. Enditem