Initially, murine antibodies were obtained by hybridoma technology, for which Kohler and Milstein received a Nobel prize.
However the dissimilarity between murine and human immune systems led to the clinical failure of these antibodies, except in some specific circumstances. Major problems associated with murine antibodies included reduced stimulation of cytotoxicity and the formation complexes after repeated administration, which resulted in mild allergic reactions and sometimes anaphylactic shock.
Chimeric and humanized monoclonal antibodies (suffixes -ximab, -zumab respectively)
To reduce murine antibody immunogenicity, murine molecules were engineered to remove immunogenic content and to increase their immunologic efficiency.
This was initially achieved by the production of chimeric and humanized antibodies. Chimeric antibodies are composed of murine variable regions fused onto human constant regions. Human gene sequences, taken from the kappa light chain and the IgG1 heavy chain, results in antibodies that are approximately 65% human. This reduces immunogenicity, and thus increases serum half-life.
Yes I have worked in biotech and I was part of clinical trial testing for both murine and chimeric MABs.
In fact I used to clone them for a living.