This Week in PNAS

In work appearing in this week's edition of PNAS, Tel Aviv University's Ronen Borenstein and Niza Frenkel describe single-step production of viral BACs of the 160-kb human herpes virus 6A. Their method of cloning, they say, is "independent of intracellular recombinations and DNA packaging constraints" and is "especially attractive for viruses that replicate inefficiently and for viruses propagated in suspension cells."

Edward Holmes of Penn State University has written an article for the Evolution in Health and Medicine Sackler Colloquium on the comparative genomics of viral emergence and in particular focuses on how this field can help scientists better understand the ability of RNA viruses to mutate and jump hosts. Swine flu is a good example, where, he says, "research reveals a marked lack of surveillance of influenza viruses in pigs ... such that the exact genesis of [the virus] (where, when, how) is uncertain."

A group of scientists led by senior author Stephen Ekker at the Mayo Clinic has performed a study looking at how genetics affects behavioral response to nicotine. Using an assay developed in zebrafish and a forward genetic screen, they found two mutations, bdav/cct8 and hbog/gabbr1.2, that have altered nicotine response. "Each have a single human ortholog, identifying two points for potential scientific, diagnostic, and drug development for nicotine biology and cessation therapeutics," they write.

Research from the International MHC and Autoimmunity Genetics Network have mapped variants within the MHC region for several immune-related diseases. Genotyping 1,472 SNPs across the MHC region in about 10,600 samples from patients with systemic lupus erythematosus, Crohn's disease, ulcerative colitis, rheumatoid arthritis, myasthenia gravis, selective IgA deficiency, and multiple sclerosis, they found "primary association signals for each disease and ... independent secondary signals," they write in the abstract. "The data demonstrate that MHC associations with autoimmune diseases result from complex, multilocus effects that span the entire region."