WSU Virology

the longer the genome, the less gene overlap is present. They confirmed that this also held for DNA viruses. But when they grouped viruses by the kind of capsids they have–icosahedral vs. flexible–they found that this relationship is strong in the icosahedral capsid viruses, but weak in those with flexible capsids.

icosahedral capsids are particularly rigid and constrained in size

Even more outrageous is the notion that genes can overlap and still code for perfectly functional proteins, because this implies that, for part of the gene at least, a different reading frame still has functional meaning. This flies against our intuition that frame-shift mutations are the deadliest of all, and has been likened to taking a paragraph of text, moving all the spaces between words down by a character, and still being able to read it, but this time with a completely different meaning!

For HIV-1, the term latency was initially used in the clinical sense to describe the long asymptomatic period between initial infection and the development of AIDS. However, with the advent of sensitive RT-PCR assays for viremia (Piatak et al. 1993), it became clear that HIV-1 replicates actively throughout the course of the infection, even during the asymptomatic period. The major mechanism by which HIV-1 evades immune responses is not latency but rather through rapid evolution of escape mutations that abrogate recognition by neutralizing antibodies and cytolytic T lymphocytes (Bailey et al. 2004). Nevertheless, it has become clear that HIV-1 can establish a state of latent infection at the level of individual T cells

“I say, ‘Use this vaccine,’ ” he said. “The safety profile is actually quite good. But we have oversold it. Use it — but just know it’s not going to work nearly as well as everyone says.”

“Not having evidence doesn’t prove it doesn’t work; we just don’t know,” said Dr. Roger Thomas, a Cochrane Collaboration coordinator for the University of Calgary in Alberta, who was an author of both of the reviews. “The intelligent decision would be to have large, publicly funded independent trials.”

“Does it work as well as the measles vaccine? No, and it’s not likely to. But the vaccine works,” Dr. Joseph Bresee, chief of epidemiology and prevention in the C.D.C.’s influenza division, said. And research is advancing to improve the effectiveness of the vaccine.