Production of hemagglutinin-neuraminidase protein in microalgae

1. A method for production of a hemagglutinin-neuraminidase (HN) polypeptide, wherein said HN polypeptide is glycosylated and comprises full length HN polypeptide, a membrane domain and a native HN signal peptide,

said method comprising culturing a recombinant microalgal host cell in a medium, wherein the recombinant microalgal host cell comprises a heterologous nucleic acid molecule comprising the sequence of SEQ ID NO:1 encoding the HN polypeptide to produce the HN polypeptide, and wherein the microalgal host cell is free of polynucleotide sequences encoding other heterologous viral polypeptides, whereby the HN polypeptide is secreted into the medium by action of the signal peptide, and

recovering the HN polypeptide from the medium.

2. The method of claim 1 , wherein the HN polypeptide is at least 90% identical to SEQ ID NO:2.

3. A method of producing a composition comprising a heterologous HN polypeptide, the method comprising:

(a) expressing a heterologous HN polypeptide encoded by a polynucleotide comprising the sequence of SEQ ID NO:1 in a microalgal host cell, wherein said HN polypeptide is glycosylated and comprises full length HN polypeptide, a membrane domain and a native HN signal peptide, and

(b) culturing the microalgal host cell under conditions sufficient to produce the heterologous FN polypeptide

wherein the composition is produced as the culture supernatant comprising the heterologous FN polypeptide, and wherein the microalgal host cell is free of polynucleotide sequences encoding other heterologous viral polypeptides.

4. The method of claim 3 , further comprising removing the culture supernatant from the composition and resuspending the heterologous HN polypeptide in an aqueous liquid carrier.

5. The method of claim 1 or claim 3 , wherein the host cell is a Labyrinthulomycota host cell.

6. The method of claim 5 , wherein the host cell is a Schizochytrium or a Thraustochytrium host cell.

7. A recombinant microalgal cell expressing an HN polypeptide, wherein said HN polypeptide is glycosylated and comprises full length HN polypeptide, a membrane domain and a native HN signal peptide, comprising a nucleic acid molecule comprising a polynucleotide sequence of SEQ ID NO:1 that encodes the HN protein, wherein the microalgal cell is free of polynucleotide sequence encoding other heterologous viral proteins.

8. The microalgal cell of claim 7 , wherein the HN protein is at least 90% sequence identical to SEQ ID NO:2.

9. The microalgal cell of claim 7 , wherein the microalgal cell is a Labyrinthulomycota cell.

10. The microalgal cell of claim 9 , wherein the microalgal cell is a Schizochytrium or a Thraustochytrium cell.

11. The method of claim 2 , wherein the HN polypeptide has the sequence of SEQ ID NO:2.

12. The microalgal cell of claim 8 , wherein the HN protein has the sequence of SEQ ID NO:2.