Plum Island, the staff of diagnostic investiga- 

 tions conducts various serological tests, virus 

 isolations, animal inoculations, and pathological 

 studies to determine if the samples were positive 

 or negative for a foreign animal disease. 



Considerable work is required to have in 

 readiness all of the virus strains, antiserums, and 

 cell cultures needed for the various diagnostic 

 tests. In addition, research is conducted on 

 various aspects of foreign diseases of animals 

 other than foot-and-mouth disease. 



RESEARCH HIGHLIGHTS 





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Foot-and-Mouth Disease (FMD) 



Viewed foot-and-mouth disease virus (FMDV) 

 in the electron microscope as a spherical particle 

 23 nanometers (about one-millionth inch) in 

 diameter with 32 capsomeres on its surface. 



Established that FMDV ribonucleic acid 

 (RNA) can be encapsidated in a bovine entero- 

 virus (BEV) protein coat and that such viral 

 particles have biophysical properties of BEV but 

 can produce FMDV in further growth cycles. 



Developed an in vitro system for the study of 

 the synthesis of FMDV-RNA. 



Showed that FMDV-infected cells contain an 

 enzyme, RNA polymerase, which is induced by 



PN-3661 



A technician cultures swine blood to determine 

 sterility. 



PN-3662 



A technician dispenses kidney cells into tissue-culture 

 bottles. 



the virus, is necessary for viral replication, but is 

 not found in normal cells. 



Showed that the virus replication activity of 

 RNA polymerase is inhibited by antibodies 

 produced in FMD-infected animals. Thus, RNA 

 polymerase may be identical to a virus-infection- 

 associated antigen (VIA). 



Demonstrated that VIA made from extracts 

 of FMDV-infected cell cultures reacted with 

 antibodies in serums from FMD-infected animals 

 in agar gel precipitin tests, forming a band 

 distinct from that of whole FMDV. A similar 

 finding was demonstrated by means of fluores- 

 cent antibody techniques. 



Established that the FMDV infection 

 associated antigen used in the VIA agar gel 

 diffusion test was a valuable tool for epizootio- 

 logical surveys. 



Found that FMDV persisted in cell cultures 

 made from the pharyngeal and esophageal cells 

 of infected cattle for as long as 24 weeks. 



Found that FMDV can infect cattle, sheep, 

 and goats and multiply in the upper respiratory 

 tract regardless of their immune status, and that 

 this infection and multiplication can occur in 

 the complete absence of clinical signs. 



Showed that a steer after intranasal inocula- 

 tion with FMDV could transmit FMDV for 7 to 



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