New animal model shows effective treatment for latent tuberculosis

December 17, 2019

San Antonio, Texas (December 17, 2019) - A major goal of tuberculosis (TB) research is to find a way to treat people with the latent (or inactive) form of the disease to keep them from developing symptomatic TB. A breakthrough study using a new animal model developed for this purpose showed a combination of two classes of antibiotics can wipe out this hidden threat. The study was published in the American Journal for Respiratory Clinical Care Medicine.

Deepak Kaushal, Ph.D., Director of the Southwest National Primate Research Center, and Jyothi Rengarajan, PhD, Associate Professor of Medicine at Emory University and the Yerkes National Primate Research Center, served as co-principal investigators of the 10-month study. Using rhesus macaques, the scientists were able to create a model of latent TB that resembles what occurs when a person is infected with Mycobacterium tuberculosis (Mtb), the bacteria that causes TB, but does not develop active disease. The bacteria are "hibernating" in the lungs, Dr. Kaushal explained.

"People with latent tuberculosis infection remain a source of disease because they can potentially reactivate at any point in time," Dr. Kaushal said. Complicating factors like an HIV infection, diabetes, aging or other diseases can trigger the latent bacteria to become symptomatic and infectious again. The current treatments for latent TB are lengthy. Many patients do not finish the course of therapy. Dr. Kaushal believes a shorter course of treatment would be beneficial.

Using low-dose infection through an aerosolization chamber, scientists gave the nonhuman primates enough TB to create a latent infection. The scientists then treated half of the animals with a once-weekly combination of antibiotics isoniazid and rifapentine for three months; the other half was untreated. This is likely the first report modeling LTBI treatment in nonhuman primates.

Afterward, the animals were infected with SIV (Simian immunodeficiency virus), which mimics HIV in humans, to test whether the drug treatment cleared bacteria from their lungs. Of the monkeys that had no treatment for latent TB, 70 percent developed active TB after SIV infection. None of the monkeys that had the three-month course of antibiotics developed active TB after SIV infection suggesting the treatment cleared the bacteria and prevented reactivation.

"The antibiotic treatment we used for this study is a new, shorter regimen the CDC recommends for treating humans with latent tuberculosis, but we did not have direct evidence for whether it completely clears latent infection" says Dr. Rengarajan. "Our experimental study in macaques showing almost complete sterilization of bacteria after treatment suggests this three-month regimen sterilizes humans as well."

This is the first time rhesus macaques were used as a model of latent TB treatment. Dr. Kaushal said the animal will be an important model for testing other TB treatment regimens going forward.

Around the world, TB claims more lives than any other infectious disease. In the U.S. alone, about 13 million people develop latent TB each year, and 15,000 to 20,000 people are diagnosed with active TB annually. Globally, close to one quarter of the population (1.8 billion) is infected with TB, according to the World Health Organization.

In an accompanying editorial published in the same journal, Dr. Andrew Vernon of the Division of TB Elimination at the Centers for Disease Control & Prevention and Dr. William Bishai of the Center for Tuberculosis Research at Johns Hopkins University write the application of this drug regimen "could presage a major step forward in TB prevention and control." They call the results of the study "dramatic."

The study was conducted at Tulane and Emory as part of a Tuberculosis Research Unit (TBRU) U19 award to Emory University (Program Directors: Henry Blumberg MD, Emory and Joel Ernst, MD, UCSF), and includes additional collaborators at Emory, UCSF and University of Florida from the TBRU-ASTRa study group.

The Tuberculosis Research Unit Network was established in 1994 to integrate scientist and clinician perspectives on the enormous health impact of the disease in TB endemic countries. Four multi-project awards empower researchers to study TB latency and persistence and their relation to active TB disease in humans.
-end-
This research was funded by a Tuberculosis Research Unit (TBRU) grant from NIH/NIAID (U19AI111211) as well as supported by the NIH Office of the Director, Office of Research Infrastructure Programs (P51OD011104 and P51OD011132) and other NIH grants (R01AI111943, R01AI134240, K24AI058609 and K24AI114444).

Texas Biomed is one of the world's leading independent biomedical research institutions dedicated to advancing health worldwide through innovative biomedical research. The Institute is home to the Southwest National Primate Research Center (SNPRC) and provides broad services in primate research. SNPRC contributes to a national network of National Primate Research Centers (NPRCs) with specialized technologies, capabilities and primate resources, many of which are unique to the SNPRC. The Center also serves investigators around the globe with research and technical procedures for collaborative projects. For more information on Texas Biomed, go to http://www.TxBiomed.org or for more information on SNPRC, visit http://www.SNPRC.org.

Dedicated to discovering causes, preventions, treatments and cures, the Yerkes National Primate Research Center (NPRC), part of Emory University's Robert W. Woodruff Health Sciences Center, is fighting diseases and improving human health and lives worldwide. The center, one of only seven NPRCs the National Institutes of Health (NIH) funds, is supported by more than $73 million in research funding (all sources, fiscal year 2019). Yerkes researchers are making landmark discoveries in microbiology and immunology; neurologic diseases; neuropharmacology; behavioral, cognitive, and developmental neuroscience; and psychiatric disorders. Since 1984, the center has been fully accredited by the AAALAC International, regarded as the gold seal of approval for laboratory animal care. For more information about Yerkes and the seven NPRCs, visit NPRC.org and follow us at @NPRCnews.

Texas Biomedical Research Institute

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.