was exchanged by the ectodomain of ldv resulting in the full length cdna clone pabv707 bhk 21 cells transfected with transcripts from this prrs recombinant could be stained with mabs against gp3 gp4 and the n protein mab 126 12 directed against the m protein but not with the mabs 126 3 and 126 4 table 2 this confirmed the above described results that these mabs reacted with the ectodomain of the m protein to test the production of infectious chimeric virus pams were infected with the supernatant of the transfected bhk 21 cells in ipma pams could be stained with all but mabs 126 3 and 126 4 table 3 in conclusion the ectodomain of the m protein can be replaced by the ectodomain of ldv resulting in the production of a chimeric virus which still infects porcine alveolar macrophages studies on coronaviruses suggest that all domains of the m protein are important for coronavirus assembly 1 the amino terminal domain of the m protein which is exposed on the outside of the virus plays a role in virus assembly in addition the carboxy terminal domain located inside the virus envelope is also important for virus assembly by interacting with the nucleocapsid this.