Historical Insights in Virology: Tulipomania to RNA Discoveries

1. Kuliah ke-2 SEJARAH VIROLOGI TUMBUHAN

2. Tulipomania – late 16th century Before it was known to be caused by a virus, tulips with color breaking symptoms were prized and traded for large sums of goods – this led to “tulipomania” in the late 1500’s • Traded for 1 Viceroy tulip bulb: • 4 tons of wheat • 8 tons of rye • 4 fat oxen • 8 fat pigs • 12 fat sheep • 2 hogsheads of wine • 4 barrels of beer • 2 barrels of butter • 1000 lbs of cheese • 1 bed with accessories • 1 full dress suit • 1 silver goblet

3. Adolf Mayer –1886 – showed that Tobacco mosaic virus was transmissible, could not find bacteria or fungi associated with disease TMV

4. Dmitri Ivanowski - 1892– showed that Tobacco mosaic virus was not retained by filters that retained all bacteria known at that time

5. Martinus Beijerinck - 1898– repeated demonstration that Tobacco mosaic virus was not retained by filters that retained all bacteria known at that time • Believed results • Did extensive dilution experiments • Showed diffusion of infectious agent through agar • Named “contagium vivum fluidum”, later virus

6. Wendell Stanley – 1935 • At Rockefeller Foundation in Princeton • Crystallized TMV, thought it was only protein TMV Stanley Hall, U.C. Berkeley

7. Bawden and Pirie - 1936 • Crystallized Tomato bushy stunt virus (TBSV); find that it and TMV contain phosphorous – conclude that it is not a protein, but is a nucleoprotein TMV TBSV

8. Markham and Smith - 1949 • Two classes of particles in purified Turnip yellow mosaic virus preparations: • light ones containing only protein, which were not infectious • heavy ones containing protein+nucleic acid, which were infectious empty full

9. Myron Brakke- 1951 • Development of density gradient centrifugation • Isopycnic: particles reach position of equal density in gradient • Rate-zonal:Particles sediment differentially through medium as a function of size, shape, and density • Equilibrium zonal: Combination of the above

10. Fraenkel-Conrat1955-1956 Virus Aa: RNA A capsid a protein • Complete, infectious TMV particles can be reconstituted in vitro from the RNA and protein components • RNA alone is infectious • RNA can be “transcapsidated” in protein from closely related virus; resulting virus has properties of RNA strain RNA reconstitute in vitro inoculate plants symptoms (A) extract virus virus Aa

11. Crick and Watson – 1956 • TMV virions are composed of one nucleic acid and many identical protein subunits: RNA does not have the coding capacity to make many different subunits

12. Casper and Klug – 1962 • Structure of Tomato bushy stunt virus solved by X-ray crystallography, the first icosahedral virus so determined

13. Heinz Sanger – 1978 • Complete sequence of Potato spindle tuber viroid • First pathogen sequence to be determined • Yielded relatively little information that was immediately useful 1 cggaactaaa ctcgtggttc ctgtggttca cacctgacct cctgagcaaa aaagaaaaaa gataggcggc tcggaggagc gcttcaggga tccccgggga aacctggagc gaactggcaa aaaaggacgg tggggagtgc ccagcggccg acaggagtaa ttcccgccga aacagggttt tcacccttcc tttcttcggg tgtccttcct cgcgcccgca ggaccacccc tcgccccctt tgcgctgtcg cttcggctac tacccggtgg aaacaactga agctcccgag aaccgctttt tctctatctt cttgcttccg gggcgagggt gtttagccct tggaaccgca gttggttcct 359

14. Paul Ahlquist– 1984 • Infectious viral RNA transcribed in vitro from cDNA clones • Done with Brome mosaic virus – with 3 RNAs • Brought reverse genetics to RNA viruses RNA Inoculate plants RNA cDNA

15. Roger Beachy– 1986 • Transgenic plants expressing TMV coat protein are resistant to virus infection • First example of “pathogen-mediated resistance”

16. Bill Dougherty – 1991 • RNA was critical component in resistance in pathogen-mediated resistance • All of the hallmarks that later came to be associated with PTGS and RNAi were first observed with Tobacco etch virus (TEV) (1993 Lindbo et al., Plant Cell 5:1749-1759)