Physicochemical 
                
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                (S)
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                (S)
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                (S)
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            | Stability of Infectivity (effects) | 
        
        
            
                 
                Cell culture grown virus rapidly inactivated below pH 7.0 (17).
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            | Virion Morphology | 
        
        
            
                 
                
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                nm
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                nm
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            | Morphogenesis | 
        
        
            
                 
                
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            | Hemagglutination | 
        
        
            
                 
                Yes
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                SMB ext. by acetone ether
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                Chick
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                6.0-7.0
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                6.2
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                4dC to 37dC
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                37dC
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                HI, CF, NT and protection challenge
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