A protein of the sialidase catalytic domain comprising a catalytic domain of a sialidase, wherein the protein comprises a sequence of the catalytic domain selected from: a) the amino acid sequence described in SEQ ID NO: 14, wherein said sequence lacks of amino acids 1 to 273 of the amino acid sequence described in SEQ ID NO: 12； b) an amino acid sequence that begins at amino acid 274 of the amino acid sequence described in SEQ ID NO: 12 and ends at amino acid 666 of the amino acid sequence described in SEQ ID NO: 12, and lacks amino acids 1 a 273 and 667 to 901 of the amino acid sequence described in SEQ ID NO: 12； c) an amino acid sequence that begins at amino acid 274 of the amino acid sequence described in SEQ ID NO: 12 and ends at amino acid residue 681 of the amino acid sequence described in SEQ ID NO: 12, and lacks amino acids 1 to 273 and 682 to 901 of the amino acid sequence described in SEQ ID NO: 12； d) an amino acid sequence that begins at amino acid 290 of the amino acid sequence described in SEQ ID NO: 12 and ends at amino acid residue 666 of the amino acid sequence described in SEQ ID NO: 12, and lacks amino acids 1 to 289 and 667 to 901 of the amino acid sequence described in SEQ ID NO: 12； and e) an amino acid sequence that begins at amino acid 290 of the amino acid sequence described in SEQ ID NO: 12 and ends at amino acid residue 681 of the amino acid sequence described in SEQ ID NO: 12 and lacks amino acids 1 to 289 and 682 to 901 of the amino acid sequence described in SEQ ID NO: 12, wherein said sialidase catalytic domain protein has sialidase activity.Una proteína del dominio catalítico de sialidasa que comprende un dominio catalítico de una sialidasa, en donde la proteína comprende una secuencia del dominio catalítico seleccionada a partir de: a) la secuencia de aminoácidos descrita en SEQ ID NO: 14, en donde dicha secuencia carece de los aminoácidos 1 a 273 de la secuencia de aminoácidos descrita en SEQ ID NO: 12； b) una secuencia de aminoác
