Severe acute respiratory syndrome, or SARS, began making headlines in 2002 when the disease spread from China's Guandong province to 37 countries around the world killing almost 800 people. But despite its dramatic emergence during the near-pandemic, scientists have been unable to make much progress on therapeutic prevention or post-infection treatment.
But now, a recent study of mice has provided some hope — in the form of algae.
Mice treated with Griffithsin, or GRFT, which is a lectin protein derived from algae, had a 100 percent survival rate after exposure to the SARS coronavirus; untreated mice, by comparison, posted a 30 percent survival rate. Scientists believe the protein has strong antiviral effects and can actually shift the shape of the sugar molecules that line the envelope surrounding the virus. The protein-rich envelope helps the virus enter cells by binding to receptors on the host cell's membrane; once inside, the virus uses the cell's reproductive mechanisms to replicate itself. Stripped of that ability by GRFT, the virus simply can't cause disease.
"While preliminary, these results are very exciting and indicate a possible therapeutic approach to future SARS or other coronaviral outbreaks," said lead author Christine Wohlford-Lenane, senior research assistant at the department of pediatrics at the University of Iowa, in a press release announcing the findings. The study was presented this week at the American Thoracic Society's 105th International Conference in San Diego.
After mice were inoculated with the SARS virus and treated with either GRFT or a placebo, researchers analyzed the extent to which the virus was able to replicate in the mice at specific periods: two, four and 10 days after infection.
Mice who weren't treated with GRFT showed 20 times more plaque-forming units of virus than the treated mice did. The lungs of untreated infected mice also showed extensive bronchitis and prominent edema, while mice treated with GRFT showed evidence of much less severe lung damage. In addition, the untreated mice shed 35 percent of their body mass, while treated mice retained their weight.
"This indicates that not only did the GRFT stop the virus from replicating, but also prevented secondary outcomes, such as weight loss, that are associated with infection," said Wohlford-Lenane.
The researchers' next step is to investigate whether mice protected from SARS by the protein actually develop a protective immune defense against future infection.
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