PN-3663 



A technician shows plaques formed by virus particles found in the blood of steers. 



8 days and that the most infectious period was 

 during the third day. 



Found a latent form of FMD characterized by 

 virus isolation from the blood in the absence of 

 specific antibody development and with 

 extremely long incubation periods. 



Determined that FMDV may be present in 

 semen of infected bulls before and after clinical 

 signs of disease and that it may be transmitted 

 to cows by artificial insemination. 



Established that FMDV survives in lymph 

 nodes and blood of beef carcasses for as long as 

 60 days, in bone marrow for more than 6 

 months, and in lymph nodes of wet, salt-cured 

 meat for as long as 50 days. 



Developed radial immunodiffusion procedures 

 for measuring FMDV in crude tissue culture 

 fluids as well as in concentrated and purified 

 preparations. 



Showed that FMDV could be spread by air 

 from infected to clean areas. 



Established a facility for the large-scale culti- 

 vation of baby hamster kidney cells in rolling 



bottles and the production, therefrom, of 100 

 milligrams per week of purified FMDV. 



Determined the dose of ionizing radiation 

 required to inactivate FMDV and its RNA. 



Found that FMDV is inactivated by organic 

 acids, and by ethylene oxide gas, when sufficient 

 humidity is present, and that beta- 

 propiolactone, acetylethyleneimine, ethylene 

 oxide may be used as inactivants when retention 

 of antigenicity is desired. 



Used polyethylene glycol for precipitation of 

 FMDV for vaccine production. 



Showed that a FMDV vaccine combining oil 

 adjuvant can be used in a vaccination program 

 involving revaccination, reducing the number of 

 vaccinations per year and giving adequate pro- 

 tection for 6 months or longer. 



Determined that purified FMD viruses inacti- 

 vatec^and combined with oil adjuvants produced 

 the first satisfactory vaccine for swine. 



Showed the possible relationship between 

 swine vesicular disease virus and Coxsackie B 

 virus of humans. 



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