Dengue treatment is making progress in animal testing

Dengue is endemic in dozens of countries, but no treatment exists.—AFP/file

TOKYO: A new dengue treatment that could become the first to prevent and treat the virus has proven effective in initial trials in monkeys, according to new research.

Dengue is transmitted by mosquitoes and affects tens of millions every year it produced brutal symptoms that have earned it the nickname “breakbone fever”.

It is endemic in dozens of countries, but no treatment exists and two vaccines that have been developed have not yet been widely approved.

Two years ago, researchers published work showing that a compound can effectively prevent the virus from multiplying in cell cultures and mice by preventing the interaction between two proteins.

Now the team has refined and tested the compound in both mice and monkeys, with “very encouraging” results, said Marnix Van Loock, head for emerging pathogens at the Janssen Companies of Johnson & Johnson, a pharmaceutical company.

In rhesus monkeys, a high dose of the compound known as JNJ-1802 completely blocked viral replication, he told AFP, while in control animals, viral RNA was detected between days three and seven after infection.

In monkeys, the compound was tested against the two most common of the four dengue strains, and only for its preventive properties, rather than for treatment.

But it was tested for both treatment and prevention in mice, against all four types of dengue, with successful results, Van Loock said.

Dengue can cause intense flu-like symptoms and sometimes develops into a severe form that can be fatal.

Because there are four different strains, infection from one does not protect against the other, and contracting dengue a second time is often more serious.

Researchers have warned that a warmer, wetter climate more hospitable to mosquitoes is likely to increase the prevalence of viruses passed on by the insect.

With no treatment available, efforts are currently focused on reducing transmission, including by infecting mosquitoes with bacteria.

A vaccine called Dengvaxia is only approved for use in some countries and is effective against a single strain.

A second vaccine, Qdenga, was approved for use by the European Union last December and also received the green light from Britain and Indonesia.

However, there are still questions to be answered about treatment, including whether it can increase vulnerability to reinfection.

When people contract dengue, the presence of the virus in their blood generally stimulates a powerful immune response that protects them from future infections.

But in some people, the immune response is weaker and that makes them vulnerable to re-infection, which can cause more serious symptoms.

It is not yet clear whether preventing or reducing viral replication can create the same vulnerability to reinfection.

The researchers will need to submit safety data from their current phase of testing before proceeding with further human trials, including field studies in dengue-affected areas.

Van Loock was hesitant to speculate on when a treatment could realistically be used.

“We’re guided by the science and the data we’re generating to really answer that question,” he said.

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