VBNC Legionella pneumophila cells are still able to produce virulence proteins.
Legionella pneumophila is the agent responsible for legionellosis. Numerous bacteria, including L. pneumophila, can enter into a viable but not culturable (VBNC) state under unfavorable environmental conditions. In this state, cells are unable to form colonies on standard medium but are still alive. Here we show that VBNC L. pneumophila cells, obtained by monochloramine treatment, were still able to synthesize proteins, some of which are involved in virulence. Protein synthesis was measured using (35)S-labeling and the proteomes of VBNC and culturable cells then compared. This analysis allowed the identification of nine proteins that were accumulated in the VBNC state. Among them, four were involved in virulence, i.e., the macrophage infectivity potentiator protein, the hypothetical protein lpl2247, the ClpP protease proteolytic subunit and the 27 kDa outer membrane protein. Others, i.e., the enoyl reductase, the electron transfer flavoprotein (alpha and beta subunits), the 50S ribosomal proteins (L1 and L25) are involved in metabolic and energy production pathways. However, resuscitation experiments performed with Acanthamoeba castellanii failed, suggesting that the accumulation of virulence factors by VBNC cells is not sufficient to maintain their virulence.
Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, Equipe Microbiologie de l'Eau, B36, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
Laëtitia
L
Alleron
Arbia
A
Khemiri
Mohamad
M
Koubar
Christian
C
Lacombe
Laurent
L
Coquet
Pascal
P
Cosette
Thierry
T
Jouenne
Jacques
J
Frere
D001426:Bacterial Proteins / Q000096:biosynthesis*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002700:Chloramines / Q000494:pharmacology; D004950:Esterases / Q000378:metabolism; D016952:Legionella pneumophila / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000472:pathogenicity*; D050296:Microbial Viability / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D020543:Proteome / Q000378:metabolism; D037521:Virulence Factors / Q000096:biosynthesis*
D001426:Bacterial Proteins; D002700:Chloramines; D020543:Proteome; D037521:Virulence Factors; D004950:Esterases; C030816:chloramine
Legionella pneumophila; Monochloramine treatment; Proteomic analysis; VBNC; Virulence factors