title: The influence of conidial Pr1 protease on pathogenicity potential of Metarhizium anisopliae senso latu to ticks.
abstract: Pr1 is a subtilisin-like protease produced by Metarhizium spp. entomopathogenic fungi, and it is recognized as heavily involved in the initial steps of the fungal invasion of arthropod-host cuticles. In the current study, correlation was sought between mortality of tick larvae and conidial Pr1 levels of one Metarhizium anisopliae senso latu (s.l.) isolate (CG 148). Conidia with different levels of pr1 gene expression and enzymatic activity were obtained by producing them on either artificial medium (to yield low Pr1 activity) or on Rhipicephalus microplus cadavers (to yield high Pr1 activity). Conidial proteolytic activity was assessed using N-suc-ala-ala-pro-phe-ρNA as the chromogenic substrate, and pr1 expression was profiled by qPCR using three genes (gpd, try, and tef) as reference genes. Pr1 enzymatic (proteolytic) activity on conidia obtained from tick cadavers was 36 U mg(-1) in comparison to 4 U mg(-1) on conidia from PDA medium. Also, pr1 gene expression level was ten times higher in conidia from tick cadavers compared to PDA medium. Bioassays of M. anisopliae s.l. CG 148 spores with elevated Pr1 proteolytic activity and gene expression levels did not demonstrate increased virulence (= significant change percent mortality of tick larvae). The minimal levels of Pr1 on conidia produced on artificial medium was adequate to afford high levels of virulence, and the elevated amounts of the enzyme on tick-cadaver-produced conidia did not induce elevated larval mortality. As long as some Pr1 activity was present, fungal virulence of isolate CG 148 against tick larvae was not elevated by increased levels of conidial Pr1.
authors: Departamento de Parasitologia Animal, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro (UFRRJ), BR 465, Km7, Seropédica, RJ, Brazil, patriciagolo@gmail.com.
authors: Patrícia S
authors: PS
authors: Golo
authors: Huarrisson A
authors: HA
authors: Santos
authors: Wendell M S
authors: WM
authors: Perinotto
authors: Simone
authors: S
authors: Quinelato
authors: Isabele C
authors: IC
authors: Angelo
authors: Mariana G
authors: MG
authors: Camargo
authors: Fillipe A
authors: FA
authors: Sá
authors: Carlos L
authors: CL
authors: Massard
authors: Éverton K K
authors: ÉK
authors: Fernandes
authors: Donald W
authors: DW
authors: Roberts
authors: Vânia R E P
authors: VR
authors: Bittencourt
mesh_terms: D000818:Animals; D001681:Biological Assay; D015971:Gene Expression Regulation, Enzymologic; D007814:Larva / Q000382:microbiology; D052981:Metarhizium / Q000201:enzymology / Q000472:pathogenicity* / Q000502:physiology; D010447:Peptide Hydrolases; D010572:Pest Control, Biological; D048494:Rhipicephalus / Q000382:microbiology*; D013172:Spores, Fungal / Q000472:pathogenicity; D014774:Virulence
chemical_list: D010447:Peptide Hydrolases