Positive signals from initial trial of dengue fever drug

The data was released by Johnson & Johnson on October 20. The company said there are currently no specific treatments for dengue, a growing threat. But “this is the first drug to show antiviral activity against dengue,” said Marnix Van Loock, head of emerging pathogens research at Johnson & Johnson, speaking at the annual meeting of the American Society of Tropical Medicine and Hygiene. The drug works by blocking the action of two viral proteins and preventing the virus from making copies of itself.

According to Reuters news agency (UK), with human trials, researchers often intentionally expose healthy volunteers to pathogens to test vaccines, treatments or better understand the diseases they cause.

In the trial, conducted with the Johns Hopkins Bloomberg School of Public Health, 10 volunteers took a high dose of Johnson & Johnson's drug five days before being injected with a strain of the dengue virus. They continued taking the drug for 21 days afterward.

Six of the 10 volunteers had no dengue virus in their blood after exposure to the pathogen, nor any signs that their immune systems were responding to the infection after 85 days of follow-up. Five people in the placebo group, who were also exposed to the dengue pathogen, had detectable virus in their blood tests.

Participants in the trial received standard care from health professionals as needed, and the virus used was a weakened version to minimize symptoms. Johnson & Johnson said the positive early data will support ongoing Phase II trials of the drug to prevent four different strains of dengue virus in real-world settings where the disease is common. The next step will be to test it as a treatment.

The big future challenge for larger-scale use of this drug is ensuring access in low- and middle-income countries where it is needed most.

The Associated Press (USA) reported that an estimated 400 million people in 130 countries contract dengue fever each year. Although the mortality rate from dengue is low - an estimated 40,000 people die each year - the disease can overwhelm health systems and force many people to miss work or school.

Traditional methods of preventing mosquito-borne diseases are largely ineffective against dengue. The Aedes aegypti mosquito that spreads dengue is resistant to insecticides. And there are four different strains of the dengue virus, making it more difficult to control with a vaccine.