Bats are pretty impressive critters. They are notorious for carrying viruses like Ebola and SARS, but somehow avoid getting these diseases themselves. They are the only mammal that can fly, and they live far longer than other mammals their size. What’s their secret? Researchers in Australia sequenced two different bat genomes and found that these unique bat characteristics are not only genetically linked, but may help in the treatment of human diseases.
By inserting a genetically modified virus into a guinea pig’s heart, researchers have come up a new kind of pacemaker.
Of the billions of cells in the human heart, a mere 10,000 pacemaker cells—collectively called the sinoatrial node—are responsible for sending the electrical pulse through the remaining heart cells. Pacemaker cells are differentiated in the embryo, but with age and disease their beating can speed up, slow down, become irregular, or even stop. In these instances doctors would normally implant a pacemaker to jolt the heartbeat back into line when needed. But these electronic devices can break, run out of batteries, introduce infection or be outgrown.
Electron micrograph of bacteria-infecting viruses
Bacteria sometimes commit suicide for the good of the group. When a virus infects a bacterium, the cell kills itself rather than allow the virus to replicate inside it and spread to the surrounding bacteria.
The way this works is that when viruses aren’t around, the bacteria manufacture both a bacterial cyanide pill—a toxin molecule they could use to wipe themselves out if they come under attack—and an antitoxin molecule that keeps the toxin in check. When a virus infects the bacterium, the toxin is released, kills the bacterial cell, and prevents the virus from spreading to other cells. It’s bad for the individual bacterial cell but good for the community—and certainly bad for the infecting virus. Now researchers have found a virus that manipulates this mechanism for its own means, saving itself by keeping its host bacteria from cellular suicide.
Where viruses and bacteria cause cancer
Strictly speaking, cancer is not contagious. But a fair number of cancers are clearly caused by viral or bacterial infections: lymphomas can be triggered by the Epstein-Barr virus, which also causes mononucleosis. Liver cancers can be caused by Hepatitis B and C. Cervical cancers can be caused by human papillomavirus, the major reason behind the development of a vaccine against it. For some of these cancers, nearly 100% of the cases have an infectious link—when researchers check to see if a virus or bacterium is working in the tumor or has left signs of its presence in a patient’s blood, the answer is nearly always yes.
A new paper in The Lancet takes a look at the very best data on the prevalence of infection-caused cancers and comes up with some striking numbers. Overall, they estimate that 16% of cancer cases worldwide in 2008 had an infectious cause—2 million out of 12.7 million.
The lair of the “beast” in Lassen Volcanic National Park
It’s not often that a scientist will say “mythological beast” with a straight face, but that’s exactly what virologist Ken Stedman told Nature News about a new virus. In a recent paper in Biology Direct, Stedman and his research team describe a genetic sequence that suggests the existence of a DNA-RNA chimera virus.
RNA and DNA viruses, referring to the type of nucleic acid they use to store genetic information, are two very distinct groups—probably more evolutionary distant than a lion and a snake. That’s why researchers were so surprised when they found a DNA virus sequence encoding a protein only ever found in RNA viruses. The sample came from a Lassen Volcanic National Park hotspring, where viruses prey on the bacteria living in the acidic water.
Takin’ one for the team.
What’s the News: Clearly, as anyone suffering through a cold right now can tell you, our immune systems aren’t all they could be when it comes to keeping us disease-free. And what’s worse, the same viruses that have some people hawking up phlegm for weeks can give their roommates or spouses no more than a brief sniffle, hammering home the fact that the immune system wealth isn’t distributed evenly. Why hasn’t evolution dealt with this problem already and given us all impenetrable defenses?
As it turns out, it’s not just that evolution takes its own sweet time. It’s also that a species benefits from having individuals be immune to some things and vulnerable to others, a new study shows.
What’s the News: We’ve long had signs that when it comes to inheritance, DNA isn’t the be-all, end-all. Trees that have the exact same genes but were raised in different greenhouses behave differently. Worms with genes that impart long life can pass on that longevity to their progeny—even if they don’t pass on the genes. Both of these phenomena, we’ve discovered, come from epigenetic changes in tags attached to DNA that control whether genes get expressed.
But every now and then we get a whiff of other possible routes for inheritance, even stranger than that. A new paper in Cell reports that worms whose grandparents had the ability to fight viruses using a fleet of tiny RNA molecules retain these molecules even when they don’t have the genes for them. They can pass these molecules down for more than a hundred generations.
Booze inhibits more than just your judgement: it impairs your immune system’s ability to fight off pathogens, according to a study published last week in the journal BMC Immunology. Researchers exposed human monocytes, a type of white blood cell vital for a functioning immune system, to an amount of alcohol equivalent to a blood alcohol concentration of 0.1 (around the legal level in most states). Compared to booze-free cells, monocytes exposed to both short- and long-term levels of alcohol produced significantly less type 1 interferons, chemicals the help recruit immune cells to stage an antiviral response (and also have anti-tumor activity). Excessive drinking has long been thought to interfere with the body’s ability to fight disease, and boozing is an important risk factor for hepatitis C and barrier to treatment in HIV. But not much had been known about the mechanisms behind the effect.
What’s the News: Researchers found that squalamine, a steroid present in the bodies of the dogfish shark, has a protective effect against several human viruses, all of which are difficult or impossible to cure with existing drugs. The chemical has so far been shown to be relatively safe in humans and can be synthesized, suggesting it could have promise as an antiviral drug in humans.
What’s the News: Scientists have developed a new carbon nanotube device (pictured above) that’s capable of detecting single cancer cells. Once implemented in hospitals, this microfluidic device could let doctors more efficiently detect the spread of cancer, especially in developing countries that don’t have the money for more sophisticated diagnostic equipment. Any improvement in detecting cancer’s spread is important, says MIT associate professor of aeronautics and astronautics Brian Wardle, because “of all deaths from cancer, 90 percent are … from tumors that spread from the original site.”
What’s the Context:
Not So Fast: The process of commercializing a technology like this takes quite a while; the previous version from four years ago is being tested in hospitals now and is may be commercially available “within the next few years.”
Next Up: The scientists are currently tweaking the device to try to catch HIV.
Reference: Grace D. Chen et al. “Nanoporous Elements in Microfluidics for Multiscale Manipulation of Bioparticles.” Small. DOI: 10.1002/smll.201002076
Image: Brian Wardle/MIT