European and American subgroup C isolates of avian metapneumovirus belong to different genetic lineages.

The gene encoding the attachment glycoprotein (G) was sequenced in three French isolates of-subgroup C avian metapneumovirus (APV-C) from ducks. With 1771 nt, this gene proved as long as recently published for North-American APV-C isolates from turkeys. The nt sequences of the duck viruses shared 99% identity but proved only 75-83% identical with their North-American counterparts, viruses of both origins encoding 585 amino acid (aa)-long G proteins. Alignments revealed more homogeneity within the European and North-American groups (at least 98 and 79% aa identity, respectively) than between European and North-American viruses (at best 70% a identity), and confirmed the presence of an extracellular divergent domain (positions 302-484) in APV-C G. A phylogenetic analysis demonstrated that North-American and French isolates of APV-C belonged to significantly different genetic lineages, in agreement with the different geographical origin and host species of these viruses.

A novel endopeptidase with a strict specificity for threonine residues at the P1' position.

An endopeptidase was purified from Archachatina ventricosa by chromatography on columns of gel filtration, DEAE-Sepharose and phenyl-Sepharose. The preparation was shown to be homogeneous by polyacrylamide gel electrophoresis and capillary electrophoresis. The purified enzyme displayed two protein bands on SDS-polyacrylamide gel electrophoresis with estimated molecular weights of 90,000 and 121,000. The protease exhibited maximum proteolytic activity at 55 degrees C and at pH 8.0, but it retained more than 85% of its activity in the pH range 7.5 to 8.5. It was completely inactivated by the chelating agents EDTA and 1,10-phenanthroline which are metalloprotease inhibitors. Studies on substrate specificity showed that only the amide bonds of peptide substrates having a threonine residue at the P1' position were hydrolyzed by the purified protease. This endopeptidase constitutes a novel tool for the study of proteins in view of its narrow and unique substrate specificity.