| No antigenic relationship to any other virus, including that of hog cholera (CF, NT, cross-protection). | No neutralizing antibody is produced in any species. The CF and many of the AGDP antigens are apparently common to all isolates. | Cross-immunity experiments indicate that there may be several immunological types; haemadsorption-inhibiting antibodies are isolate specific. ( [1] , [2] , [4] , [8] ) | |
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