BREAKTHROUGHS BLOG

September 05, 2016

Research Roundup: A cancer fighting parasite, drug resistance among STIs and fungi, and a first-of-its-kind virus

Senior Program Assistant
GHTC

The Toxoplasma gondii parasite is infamous for consuming brain tissue, causing brain cancer, and even altering the behavior of infected individuals. However, new research suggests that it could be modified and used to treat ovarian cancer. The team of scientists at Dartmouth University created a weakened version of T. gondii, removing the genes that enable the parasite to take over its host’s cells. Next, mice with aggressive ovarian cancer were inoculated with the weakened parasite. The study demonstrated that the presence of T. gondii, along with certain proteins excreted by the parasite, resulted in an enhanced immune response to ovarian cancer tumors. While none of the mice were completely cured—which could in part be attributable to the late stage of cancer at the time of treatment—those treated with the weakened parasite survived an additional 40 days on average.

Colorized scanning electron micrograph of Neisseria gonorrhoeae bacteria, which causes gonorrhea.
Colorized scanning electron micrograph of Neisseria gonorrhoeae bacteria, which causes gonorrhea (Photo: National Institute of Allergy and Infectious Diseases, National Institutes of Health).

The World Health Organization (WHO) has issued new treatment guidelines for chlamydia, gonorrhea, and syphilis, as the three sexually transmitted infections (STIs) grow increasingly resistant to antibiotics. While resistant strains of chlamydia and syphilis are rare, multidrug-resistant gonorrhea has emerged in at least ten countries, and resistance to six classes of antibiotics has been reported. The WHO is calling for enhanced surveillance of drug-resistant strains of gonorrhea, and recommends that national treatment guidelines be determined based on local patterns of resistance. While syphilis is curable with a single dose of benzathine penicillin, the supply of the drug is low, and stock outs have been reported in a number of countries. While early stages of these three STIs are often asymptomatic, they can cause significant long-term damage, including pelvic inflammatory disease and infertility. Furthermore, they can be transmitted from mother-to-child during pregnancy and childbirth, and can increase the risk of ectopic pregnancy, miscarriage, stillbirth, and newborn death.

As bacteria grow resistant to antibiotics, so too do fungi to antifungals. Each year, fungal infections result in 1 million deaths, and strains of both the aspergillus and candida fungi are growing resistant to the azole class of antifungals. While there are more than 20 classes of antibiotics, there are only four classes of antifungals, and thus, resistance to just one class of medicines is a major cause for concern. Scientists believe the leading cause of fungal resistance is the widespread use of fungicides on crops and in certain household paints and coatings.

While dissecting mosquitoes in Guaico, Trinidad, researchers at the US Army Medical Research Institute of Infectious Diseases discovered a new and bewildering virus, configured unlike any other virus known to infect animals. Most viruses are comprised of a handful of genes packaged into one particle, however, the five genes of Guaico Culex exist as independent particles, and can only infect a mosquito if at least four of the five are present. Previously, viruses with this structure—known as multicomponent genomes—had only been found in plants and fungi. While humans are not susceptible to Guiaco Culex, a related virus has been found in monkeys, indicating that another multicomponent virus could infect humans.

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