Abstract: A method of producing an antibody fragment for a target antigen includes administering an immunizing mixture containing the target antigen to a cartilaginous fish for at least two times; collecting a blood sample from the cartilaginous fish; extracting RNAs from the blood sample; subjecting said RNAs to reverse transcription to obtain a complementary DNA, and optionally amplifying the cDNA to obtain a mixture of amplified cDNAs followed by purification. Also covered are methods of producing an antibody fragment from a shark; antibody fragments obtained from the method; a kit comprising antibody fragments; and methods of determining the presence and/or amount of a target antigen in a sample.

Abstract: The invention relates to surface modified extracellular vesicles, wherein the extracellular vesicles comprise an exogenous polypeptide tag that is covalently linked to a membrane protein of the extracellular vesicles. In a particular embodiment, the tag is covalently linked to the membrane protein of microvesicles by sortase-mediated ligation. Methods of preparing said extracellular vesicles and methods of using said extracellular vesicles loaded with therapeutic molecules for treating a disease are also disclosed herein.

Abstract: A method of producing an antibody fragment for a target antigen includes administering an immunizing mixture containing the target antigen to a cartilaginous fish for at least two times; collecting a blood sample from the cartilaginous fish; extracting RNAs from the blood sample; subjecting said RNAs to reverse transcription to obtain a complementary DNA, and optionally amplifying the cDNA to obtain a mixture of amplified cDNAs followed by purification. Also covered are methods of producing an antibody fragment from a shark; antibody fragments obtained from the method; a kit comprising antibody fragments; and methods of determining the presence and/or amount of a target antigen in a sample.