Retroviruses are viruses made up of RNA genetic material. Endogenous retroviruses (ERV) are those sequences derived from retroviral infections introduced into the germinal line cells that, being incorporated in the genome, are transmitted from generation to generation. According to a number of investigations, the expression of ERV can benefit the host if it is controlled; it can help, for example, in the protection of the embryo. However, given its pathogenic nature, ERV also tends to be linked to cancer, schizophrenia and autoimmune diseases.

Superantigens, the toxins produced by staphylococcus bacteria, are more complex than previously believed, reveals a team of researchers from the University of Gothenburg in an article published today in the scientific journal Nature Communications. Their discovery shows that the body's immune system can cause more illnesses than realised.

The number of people infected with HIV/AIDS in sub-Saharan Africa is projected to far outstrip available resources for treatment by the end of the decade, forcing African nations to make difficult choices about how to allocate inadequate supplies of lifesaving antiretroviral therapy (ART), says a new report by the Institute of Medicine. It calls for a renewed emphasis on reducing the rate of new infections, promoting more efficient models of care, and encouraging shared responsibility between African nations and the U.S. for treatment and prevention efforts, which could greatly improve prospects for 2020 and beyond.

Breast cancers that arise sporadically, rather than through inheritance of certain genes, likely start with defects of DNA repair mechanisms that allow environmentally triggered mutations to accumulate, according to researchers at the University of Pittsburgh School of Medicine, Magee-Womens Hospital of UPMC and the University of Pittsburgh Cancer Institute. The findings, reported this week in the early online edition of the Proceedings of the National Academy of Sciences, indicate that potent chemotherapy drugs that target DNA in later-stage cancers could be an effective way to treat the earliest of breast tumors.

Whitehead Institute researchers have shown in mouse models that overexpression of the microRNA 125b (miR-125b) can independently cause leukemia and accelerate the disease's progression. Their results are published in this week's online edition of the Proceedings of the National Academy of Sciences (PNAS).

Humans are known to play it safe in a situation when they aren't sure of the odds, or don't have confidence in their judgments. We don't like to choose the unknown.

Long a staple of nature documentaries, the somewhat bizarre development of a grub-like pink marsupial embryo outside the mother's womb is curious in another way.