Monoclonal Antibodies Incorporated into Neotyphodium coenophialum Fungal Cultures: Inhibition of Fungal Growth and Stability of Antibodies

Abstract

Three monoclonal antibodies (mAbs) produced against proteins from the tall fescue (Festuca arundinacea Schreb.) fungal endophyte Neotyphodium coenophialum hybridize exclusively to a fungal protein under denaturing conditions. The protein is approximately 88 kDa in size. These mAbs were individually incorporated into liquid medium to determine their effects on fungal growth in culture. Neotyphodium-specific mAbs inhibited fungal growth for the duration of the study. Fungal cultures grown in the presence of Neotyphodium-naive mAbs or in the absence of all mAbs grew unimpeded. Bright-field microscopy and immunohistochemical studies of cultures containing Neotyphodium-specific mAbs revealed a change in mycelia morphology with clumps exhibiting a gelatinous matrix containing sparse hyphae, while cultures receiving Neotyphodium-naive mAbs in medium demonstrated unrestricted growth with overlapping and branched hyphae. In liquid culture devoid of fungal isolates, mAbs were stable and detected throughout the experiment, but were below threshold detection levels within 15 min following inclusion in liquid cultures containing Neotyphodium spp., indicating rapid binding to fungal mycelia. Monoclonal antibodies may provide a new method to help control plant pathogenic fungi where chemical or genetic means are not feasible.