viruses

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Why are pathogens rarely resistant to vaccines?

We have all heard the horrifying tales of incurable bacterial infections due to antibiotic resistance. But why don’t we see pathogens becoming resistant to vaccines? Intuitively, it seems that vaccines, like antibiotics, put selective pressure on pathogens. The selective force should drive the evolution of vaccine resistance, right? David Kennedy and Andrew Read explore this quandary in their recent publication in the Proceedings of the Royal Society.

Historically, when vaccine resistance arises, it takes much longer compared to antibiotic resistance. Vaccines created as early as the 1920s are still effective today while resistance to a new antibiotic can develop within a few years. Because the evolution of vaccine resistance is so rare, vaccines may be a solution to the drug resistance problems we face today. Vaccines reduce the need for antibiotic treatment and also decrease the number of cases and spread of infections. (more…)

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Mosquito-borne illnesses may increase due to global warming

Mosquito bites are such a nuisance. They itch intensely for days, you can't help but scratch them, and you are left with a scar to remember them by. For much of the world, this is the aftermath of a mosquito bite. But in warm tropical climates, mosquitos are carriers of a variety of microbes pathogenic to humans. Dengue, malaria, West Nile, yellow fever, and Zika are all examples mosquito-borne illnesses. (more…)

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Microbes in costumes trick the immune system

Halloween has finally arrived and everyone around you has been busy working on their costumes in anticipation for this glorious day of tricks and treats. Come Halloween night, you may not even recognize the faces behind the costumes. How would you tell apart friends with a sweet tooth from foes ready for some tricks?

For some bacteria, putting on costumes is an everyday event when it comes to tricking the immune system. The immune system distinguishes the body's own cells from those of invading bacteria and viruses. Since the microbe's outer membrane is usually the first thing the immune system sees, the body takes advantage of molecules found on the outer membrane to generate an immune response. This seems like a wise defense mechanism but microbes have several tricks up their sleeves; they disguise themselves from the immune response by changing molecules on their outer membrane (antigenic variation) or by turning on and off expression of genes encoding for surface molecules (phase variation). (more…)