Characterization of neuraminidases from myxoviruses

• 1.

  1. A relatively simple and reproducible method for the isolation and purification of viral neuraminidases, as already reported in a preliminary note, has been shown to be of general usefulness for influenza virus enzymes but to a lesser extent for parainfluenza virus enzymes. The properties of the viral enzymes prepared in this way are presented.

• 2.

  2. A comparative investigation of the properties of the enzymes of A2 virus, fowl plague virus (FPV), and Newcastle disease virus (NDV) revealed many differences among them. This was particularly evident in their antigens; minor differences were found in the pH optima, $\text{K}{}_{\mathrm{m}}$, substrate specificity and heat stability of the enzymes from the 3 representative myxoviruses. FPV and NDV enzymes have not been previously characterized.

• 3.

  3. The sedimentation coefficients of these enzymes were in the same range as Those measured by the transport and optical methods (9–10 S). This is in agreement with the values of other influenza enzymes prepared and analyzed by other techniques (9–10 S), but contrasts with the value of 5.5 S for a bacterial neuraminidase, Vibrio cholerae enzyme.

• 4.

  4. The final purity of the A2 virus and FPV enzymes was determined by preparing antisera to the enzymes. Such antisera were found to be devoid of antibodies against other virus-specific surface antigen(s). The utility of highly specific antiserum for investigating the role of neuraminidase during virus multiplication, and the use of the antigenic type-specific property of viral enzymes as a genetic marker are discussed.