Researchers in Japan have transformed mosquitoes into vaccine-carrying syringes by genetically engineering the insects to express the vaccine for leishmaniasis--a parasitic disease transmitted by the sandfly--in their saliva. According to a study in Insect Molecular Biology, mice bitten by these mosquitoes produced antibodies against the parasite. It's not yet clear whether the immune response was strong enough to protect against infection.

"Following bites, protective immune responses are induced, just like a conventional vaccination but with no pain and no cost," said lead researcher Shigeto Yoshida, from the Jichi Medical University in JapanYoshida, in a press release from the journal. "What's more continuous exposure to bites will maintain high levels of protective immunity, through natural boosting, for a life time. So the insect shifts from being a pest to being beneficial."

Researchers consider the project more of a proof of principle experiment than a viable public health option, at least for now. According to an article on ScienceNow,

There's a huge variation in the number of mosquito bites one person received compared with the next, so people exposed to the transgenic mosquitoes would get vastly different doses of the vaccine; it would be a bit like giving some people one measles jab and others 500 of them. No regulatory agency would sign off on that, says molecular biologist Robert Sinden of Imperial College London. Releasing the mosquitoes would also mean vaccinating people without their informed consent, an ethical no-no. Yoshida concedes that the mosquito would be "unacceptable" as a human vaccine-delivery mechanism.

However, flying vaccinators-or "flying syringes" as some have dubbed them -may have potential in fighting animal disease, says [David O'Brochta, an insect molecular geneticist at the University of Maryland, College Park]. Animals don't need to give their consent, and the variable dosage would be less of a concern.

Laser light was focused on the region of this mouse cell indicated by the red dot, activating a hybrid version of a protein called Rac and causing the cell to change shape and move. Credit: Yi Wu, UNC-Chapel Hill

Researchers at the University of North Carolina in Chapel Hill and the Max Planck Institute in Heidelberg, Germany have genetically engineered animal cells to make proteins that can be turned on and off using visible light.

The researchers spliced a gene for a light-activated protein with the gene for a protein called Rac, which is known to be involved in regulating healthy cell movements as well as the movement of cancer cells. Researchers then focused laser light to locally activate the proteins, causing protrusions that led to cell movement. The work was described this week in the journal Nature.

The location of a protein within the cell plays a role in determining the cell's behaviors, but this has been difficult to study. The researchers hope using light activation will be a good method.

Here's how it works: the light-activated portion of the protein blocks the binding site on Rac. When it's illuminated, the block is removed and Rac can function. A second pulse of light at a different wavelength causes the block to move back into position, deactivating the protein.

The technique should be compatible with other proteins in addition to Rac. In the past, researchers have made proteins that are activated by ultraviolet radiation, which is toxic to cells. And these previous proteins couldn't be turned off again; the new ones can.

Marmoset monkeys engineered to carry the gene for green fluorescent protein. The soles of the animals' feet glow green when shown under UV light. Courtesy of E. Sasaki et al., 2009

Last month in Japan, a very special marmoset monkey was born--one who inherited from his parents not only their marmoset DNA, but also a jellyfish gene for green fluorescent protein (GFP) that makes both the animal and his parents glow green under fluorescent light. The monkey parents aren't the first primates to fluoresce, but they are the first to pass a genetically engineered trait to their offspring. Scientists hope to use the approach to create animal models of neurological diseases, such as Parkinson's, which cannot be adequately reproduced in rodents--the typical subjects of genetic engineering.

"The birth of this transgenic marmoset baby is undoubtedly a milestone," write Gerald Schatten and Shoukhrat Mitalipov in a piece accompanying the paper, published today in the journal Nature. Scientists have previously created a menagerie of transgenic animals, including rats, rabbits, pigs, cows, cats, dogs, and even monkeys (in one study, scientists created monkeys that genetically mimic Huntington's disease), but "no study has shown transmission of foreign DNA to gametes--the sperm and egg--which is essential for the generation of transgenic offspring. These offspring could then be bred to create transgenic-primate strains," they add.

The ability to genetically engineer primates is essential for creating more-accurate animal models of human diseases, especially neurological ones. For example, Schatten and Mitalipov say,

Mice engineered to express the cystic fibrosis gene, for example, do not develop the lung problems that typify this disorder . . . Disorders of higher brain function, such as Alzheimer's disease, are especially challenging to reproduce in rodents, and here, as with many other diseases, it is our closest animal relatives--the non-human primates--that offer potentially invaluable biological models.

To create the transgenic monkeys, researchers injected viruses carrying the gene for GFP into 91 marmoset embryos. Eighty healthy transgenic embryos were then transplanted into surrogate mothers, who birthed five glowing offspring. Three glowing second-generation marmosets have been born since April.