O-mannosyltransferase deficient filamentous fungal cells and methods of use thereof

1. A Protein O-mannosyltransferase 1 (PMT1)-deficient filamentous fungal cell comprising

a) a first mutation in a gene encoding an endogenous protease that eliminates an endogenous protease activity as compared to a parental filamentous fungal cell which does not have said first mutation, said endogenous protease being selected among aspartic proteases, trypsin-like serine proteases, subtilisin proteases, glutamic proteases and sedolisin proteases;

b) a second mutation in a PMT1 gene that reduces endogenous O-mannosyltransferase activity compared to a parental filamentous fungal cell which does not have said second mutation, wherein the reduced endogenous O-mannosyltransferase activity results from a deletion or a disruption of a PMT1 gene encoding a polypeptide of SEQ ID NO:2 or SEQ ID NO:12;

c) a third mutation that eliminates the level of expression of an dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase (ALG3) gene compared to the level of expression in a parental cell which does not have such third mutation;

d) a first polynucleotide encoding a N-acetylglucosaminyltransferase I catalytic domain and a second polynucleotide encoding a N-acetylglucosaminyltransferase II catalytic domain,

e) a polynucleotide encoding a β1,4 galactosyltransferase; and

f) a polynucleotide encoding a mammalian antibody comprising a heavy chain and a light chain;

wherein:

the mammalian antibody is secreted by the PMT1-deficient filamentous fungal cell upon expression of the polynucleotide encoding the mammalian antibody;

said antibody comprising reduced O-mannosylation on the light chain, said reduced O-mannosylation being less than about 10% that of a light chain secreted by said parental filamentous fungal cell which does not have said second mutation, O-mannosylation being defined as mole % of mannose residues per polypeptide chain;

said antibody comprising core G0 N-glycan structure as the major glycoform; and,

said filamentous fungal cell is a Trichoderma or Myceliophthora cell.

2. The PMT1-deficient filamentous fungal cell of claim 1 , further comprising one or more polynucleotides encoding a polypeptide selected from the group consisting of:

a) α1,2 mannosidase;

b) α mannosidase II; and,

c) fucosyltransferase.

3. The PMT1-deficient filamentous fungal cell of claim 1 , wherein said cell is a Trichoderma cell comprising a mutation that reduces or eliminates the protein O-mannosyltransferase activity of Trichoderma pmt1.

4. The PMT1-deficient filamentous fungal cell of claim 1 , wherein said cell is a Trichoderma cell, for example Trichoderma reesei , and said cell comprises mutations that reduce or eliminate the activity of

a) the three endogenous proteases pep1, tsp1 and slp1;

b) the three endogenous proteases gap1, slp1 and pep1;

c) the three endogenous proteases selected from the group consisting of pep1, pep2, pep3, pep4, pep5, pep8, pep11, pep12, tsp1, slp1, slp2, slp3, slp7, gap1 and gap2;

d) three to six proteases selected from the group consisting of pep1, pep2, pep3, pep4, pep5, tsp1, slp1, slp2, slp3, gap1 and gap2; or

e) seven to ten proteases selected from the group consisting of pep1, pep2, pep3, pep4, pep5, pep7, pep8, tsp1, slp1, slp2, slp3, slp5, slp6, slp7, slp8, tpp1, gap1 and gap2.

5. The PMT1-deficient filamentous fungal cell of claim 1 , wherein the O-mannosylation level on the expressed light chain of the antibody is reduced to 0%.

6. The PMT1-deficient filamentous fungal cell of claim 1 , wherein the polynucleotide encoding a β1,4 galactosyltransferase is a human β1,4 galactosyltransferase.