Mitochondrial haplotypes of Aelurostrongylus abstrusus and Troglostrongylus brevior (Nematoda, Metastrongyloidea) from domestic and wild felids

The lungworm Aelurostrongylus abstrusus is the most important respiratory parasite of domestic cats. Pulmonary aelurostrongylosis has been reported in wild felids, though unequivocally evidence of wildlife infection by A. abstrusus is scant. Recently, Troglostrongylus brevior, a lungworm usually infecting wild felids, has been described in domestic cats from Mediterranean areas. The present work evaluates the sequence variation of an informative region within the gene encoding the mitochondrial cytochrome c oxidase subunit 1 of A. abstrusus and T. brevior, in order to provide novel information on the genetic make-up of these lungworms. Parasitic stages of A. abstrusus and T. brevior were collected from domestic and wild hosts (i.e., domestic cat, European wildcat, caracal, serval, and lion) from Italy, Greece, and South Africa. Five (HI-HV) and four (HI-HIV) haplotypes were recorded for A. abstrusus and T. brevior, respectively, mostly shared between domestic and wild felids in different geographical areas. The phylogenetic analysis showed that all haplotypes of A. abstrusus and T. brevior clustered as monophyletic groups with a strong nodal support, indicating that all haplotypes identified were distinct from each other. All sequence types represent two distinct species, A. abstrusus and T. brevior, and these genetic convergences are also detected within and among populations of these nematodes, irrespective of their hosts and geographical origin. The occurrence of A. abstrusus and T. brevior haplotypes in different hosts from the same regions and between different countries indicates that the same lungworm populations circulate in domestic and wild hosts under the same routes of transmission.