Flu season is gearing up in the northern hemisphere, and this year’s strains appear more virulent than usual. In the United States, the Centers for Disease Control declared an epidemic on January 11; the CDC estimates that between 3,000 and 49,000 people die from influenza or its complications every year. By comparison, the infamous flu of 1918 may have killed 500,000 Americans. Although the very young, elderly, and diseased bear the highest risk of death, healthy adults still bear the responsibility of minimizing overall transmission of the virus. In other words, everyone should get vaccinated. On ERV, Abbie Smith writes that the influenza virus is highly mutable, and we must devise a fresh vaccine every year in anticipation of its new forms. This year’s vaccine has an efficacy of 62%, better than average. Meanwhile, on We Beasties, Kevin Bonham explains what happens when you are infected by more than one pathogen at a time.
In Uganda, the fourth outbreak of Ebola in twelve years has killed sixteen people. On We Beasties, Kevin Bonham says the virus is “readily transmissible,” kills quickly and assuredly, “and the way it kills is gruesome – causing massive bleeding from all orifices.” These may seem like dominant characteristics, but a virus is not a predator. Bonham says Ebola viruses, like other emerging diseases, are “poorly adapted for our immune systems,” and wipe out their hosts too quickly to spread. But all that can, of course, change. On Aetiology, Tara C. Smith details the history of outbreaks in Uganda, and the methods of transmission from person to person. She says that fruit bats are likely reservoirs for the virus, with non-human primates acting as an amplifying species.
On ERV, Abbie Smith writes “Malaria kills 1.24 million people a year. Mostly babies under 5 years old.” Malaria, although carried by mosquitoes, is caused by a single-celled protist which infects the liver and goes on to parasitize red blood cells. Now, a little genetic engineering could put a stop to this scourge. Smith says “Mosquitoes have a symbiotic relationship with their bacteria the same way we do—they need their ‘good’ bacteria to get all the nutrients they need to survive.” By tweaking the protein output of one such bacteria, scientists have made mosquito guts inhospitable to malaria. The test result? An 84% decrease in the number of mosquitoes carrying malaria, and a 98% reduction in malarial replication among carriers. Of course, mosquitoes aren’t the only animals that support friendly bacteria—and researchers at the Weizmann Institute are discovering that our friendly bacteria support a number of viruses. They identified hundreds of different bacteriophages “thanks to the fact that bacteria keep ‘files’ within their genome of every virus that has ever tried to attack them.” Some of these phages may confer benefits to our internal ecosystem. And humanity has 80% of them in common.
On ERV, Abbie Smith reports that scientists have discovered an entirely new branch of viruses in the boiling acid pools of Yellowstone National Park. By analyzing RNA segments from the pools, researchers inferred the existence of positive-strand RNA viruses with unknown genetic configurations. Smith writes, “These viruses are not just kinda new. They are really really different from the RNA viruses we already know about!” They infect primordial single-celled organisms called Archaea which thrive in the extreme heat of the pools. On the multicellular side of life, Dr. Dolittle shares the first pictures of “a new family of limbless caecilian amphibians” from India. Although they look like worms, “genetic testing and comparative analyses of their cranial anatomy show that they are in fact an ancient lineage of amphibians that first appeared ~140 million years ago.” This seems like a clear example of convergent evolution–does living in the dirt lead one to look like an earthworm? Or do these caecilians gain some advantage through resemblance?
We’ve all heard of bird and swine flu, but bats, which comprise “about a fifth of all known mammalian species,” also carry a diverse host of viruses. By swabbing the rectums of little yellow-shouldered bats, researchers in Guatemala discovered a new influenza virus that defies easy classification. Flu viruses are described by two key genes—hence the name ‘H1N1.’ Tara C. Smith writes “The novel bat virus was a completely new H type—type 17 (provisional, they note, pending further analyses). The NA gene was also highly divergent.” Smith continues “the authors did do some molecular work suggesting that these novel bat viruses could combine with human viruses and form a functional recombinant virus.” It’s only a matter of time. Meanwhile Abbie Smith explains why some individuals won’t develop immunity from a vaccine. She writes “Measles needs a protein on the surface of your cells in order to successfully mediate infection: CD46.” The virus must interact with this protein to infect a cell, but antibodies generated by a vaccine get in the way. Looking at the CD46 gene, researchers found that “children who had mutations at the right spot, in a particular flavor, seemed to respond better than others. But if a child had a mutation at the right spot, but not a mutation of the right flavor, they didnt respond as well.” Luckily, herd immunity can protect non-responders—as long as everyone else gets vaccinated too.
- Holy influenza, batman! on Aetiology
- ‘Not responding well to vaccines’– It is in your genes (well, partially) on ERV
Posted to the homepage on February 28, 2012.
ERV familiarizes us with the different “layers” of the immune system, including intrinsic, innate, and adaptive immunity. The last layer makes specific antibodies to recognize pathogens, but in the case of HIV, capable antibodies aren’t enough to stave off the progression of disease. ERV writes, “HIV-1 evolves to escape these antibodies…and your body can’t catch up.” The high mutability of HIV-1 makes for a very plastic envelope, meaning the virus continually shifts shape and evades the watchful eye of the immune system. In another post, ERV explains that antibodies make diseases like Dengue fever more deadly, as “non-neutralizing antibodies attached to viruses cause them to ‘stick’ to cells they normally couldn’t infect.” This phenomenon leads ERV to warn “anything but a ‘perfect’ vaccine could cause more severe disease after exposure.” On Neurotopia, Scicurious tells how inventive researchers made a “cocaine vaccine,” allowing antibodies to bind to chemical agents and keep them from passing into the brain. And on Effect Measure, Revere considers the possibility “abortive rabies” in the case of a girl who had antibodies for the deadly virus but no trace of infection.
Links below the fold.
Continue reading “All About Antibodies”
Vaccines have guarded health and life for centuries, relegating once devastating diseases to near total obscurity. But many people now take vaccines for granted, and some blame vaccines for autism and other disorders. On Respectful Insolence, Orac reports the downfall of 1998 research which first tied MMR vaccines to the occurrence of autism in children. As Orac writes, “hearing that the man whose bad science launched a thousand quackeries had finally been declared unethical and dishonest […] brought joy to my heart, the joy that comes with seeing justice done.” ERV jumps on other news, concerned that it could fuel anti-vaccine alarmism. Researchers inspecting animal vaccines discovered an infectious endogenous retrovirus originating from the cat cell lines used in vaccine production. This “distinct-from-but-related-to feline leukemia virus” raises concerns about vaccines passing ERVs from one species to another. Finally, Janet Stemwedel on Adventures in Ethics in Science vents some steam after reading student attitudes toward H1N1 vaccination in the school newspaper. Janet criticizes both the newspaper for juxtaposing “reliable information from experts with whatever a student wandering across the reporter’s path might happen to opine,” and the students themselves for holding forth their unscientific optimism.
Links below the fold.
Continue reading “A Booster Shot of Science”