Thread by @TimothyChase

@lalani_safina (1/n) I think science literate non-specialists like myself tend to view the spike as a largely static trimeric structure - but for the harpoon-transformation that takes place when binding to the receptor. This structure and strategy, by the way, is widespread among viruses, ...

@lalani_safina (2/n) RNA, DNA, single and double stranded alike. See for example,

"When viruses infect cells, they employ molecular 'harpoons' to snare their intended target...."

12/17/1999 

Viral Harpoon Reveals Ancestry of Measles, Mumps Viruses
hhmi.org/news/lamb.html

@lalani_safina (3/n) "Recently, a team of scientists identified and determined the three-dimensional structure of the harpoon protein used by a large family of pathogenic viruses to grab hold of and fuse to host cells..."

@lalani_safina (4/n) "Surprisingly, the protein's structure suggests that viruses that cause measles and mumps may be viral cousins of HIV, influeunz and Ebola virus."

@lalani_safina (5/n) This particular type of fusion protein is a class I viral fusion protein.  For a survey of viral fusion proteins, one might look at:

ncbi.nlm.nih.gov/pmc/articles/P…

@lalani_safina (6/n) As for how the fusion proteins of such diverse viruses could have a common ancestor, it's worth recognizing that at least in the realm of bacterial viruses (bacteriophages) , viruses have a modular structure and mosaic nature.

Please see:

pnas.org/content/96/5/2…

@lalani_safina (7/n) For example, phages may insert themselves into the genome of a host during their temperate phase as a prophage and through recombination acquire a gene from another prophage.

@lalani_safina (8/n) One family of viruses which may be of interest are adenoviruses. Typically they are associated with respiratory and intestinal illness. It has been discovered that they are closely related to a phage by the name of PRD1.

Please see for example:

cell.com/fulltext/S0092…

@lalani_safina (9/n) It turns out that PRD1 and adenoviruses are also related to phages found in archaea.

Please see:

sciencedirect.com/science/articl…