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

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.