Tiny fungi may have sex while infecting humans

Oct 30, 2008

A fungus called microsporidia that causes chronic diarrhea in AIDS patients, organ transplant recipients and travelers has been identified as a member of the family of fungi that have been discovered to reproduce sexually. A team at Duke University Medical Center has proven that microsporidia are true fungi and that this species most likely undergoes a form of sexual reproduction during infection of humans and other host animals.

The findings could help develop effective treatments against these common global pathogens and may help explain their most virulent attacks.

"Microsporidian infections are hard to treat because until now we haven't known a lot about this common pathogen," says Soo Chan Lee, Ph.D., lead author and a postdoctoral researcher in the Duke Department of Molecular Genetics and Microbiology. "Up to 50 percent of AIDS patients have microsporidial infections and develop chronic diarrhea. These infections are also detected in patients with traveler's diarrhea, and also in children, organ transplant recipients and the elderly."

Of the 1200 species of microsporidia, more than a dozen infect humans. Their identity had been obscured because these tiny fungi cannot live outside of an infected host cell and they have a small number of genes which are rapidly evolving.

The Duke scientists used two genetic studies to show that microsporidia apparently evolved from sexual fungi and are closely related to the zygomycete fungus in particular.

They found that microsporidia share 33 genes out of 2,000 with zygomycetes. which the microsporidia did not share with other fungi. This genomic signature also shows that microsporidia and zygomycetes likely shared a common ancestor and are more distantly related to other known fungal lineages.

In addition, these two types of fungi have the same sex-locus genes – and in the same order – in their DNA. Other genes involved in sexual reproduction are also present. The findings suggest that microsporidia may have a genetically controlled sexual cycle, and may be undergoing sexual reproduction while they infect the host, Lee said.

Lee said the next step is to explore the sexual reproduction of these species, which may cause more severe (more virulent) infections because they use the host's cellular environment and machinery as a safe haven in which to reproduce.

"These studies resolve the enigma of the evolutionary origins and proper placement
of this highly successful group of pathogens, and provide better approaches to their experimental study," said senior author Joseph Heitman, M.D., Ph.D., director of the Center for Microbial Pathogenesis and director of the Duke University Program in Genetics and Genomics.

The team will pursue further studies with Duke genetic researchers Raphael Valdivia, Ph.D., and Alejandro Aballay, Ph.D., using cultured cells and C. elegans, a worm that researchers recently found is a natural host for microsporidia. "Using this roundworm may prove to be a useful way to study microsporidia genetics in a living creature," Heitman said.

Source: Duke University Medical Center

Explore further: Research milestone in CCHF virus could help identify new treatments

add to favorites email to friend print save as pdf

Related Stories

Flying robots will go where humans can't

27 minutes ago

There are many situations where it's impossible, complicated or too time-consuming for humans to enter and carry out operations. Think of contaminated areas following a nuclear accident, or the need to erect ...

Fly ash builds green cement mixture

27 minutes ago

An eco-friendly cement, known as Alkali Pozzolan Cement (APC), containing a mixture of fly ash, dry lime powder and sodium sulphate under specific scaffolding conditions has been developed by Curtin University ...

Manure offsets fertiliser's nano-scale changes

27 minutes ago

A UWA study has shown how long-term use of chemical fertilisers changes the soil on a nanoparticle scale and how these changes can be avoided by adding organic matter such as manure.

Video: MAVEN set to slide into orbit around Mars

7 minutes ago

A NASA mission to Mars led by the University of Colorado Boulder is set to slide into orbit around the red planet this week after a 10-month, 442-million mile chase through the inner solar system. 

Recommended for you

A new way to prevent the spread of devastating diseases

5 hours ago

For decades, researchers have tried to develop broadly effective vaccines to prevent the spread of illnesses such as HIV, malaria, and tuberculosis. While limited progress has been made along these lines, ...

New molecule allows for increase in stem cell transplants

6 hours ago

Investigators from the Institute for Research in Immunology and Cancer (IRIC) at the Université de Montréal have just published, in the prestigious magazine Science, the announcement of the discovery of a new molecule, the fi ...

Team explores STXBP5 gene and its role in blood clotting

8 hours ago

Two independent groups of researchers led by Sidney (Wally) Whiteheart, PhD, of the University of Kentucky, and Charles Lowenstein, MD, of the University of Rochester, have published important studies exploring the role that ...

User comments : 0