%0 Journal Article
%T Interaction between Mycobacterium avium subsp. paratuberculosis and environmental protozoa
%A Lynne Whan
%A Irene R Grant
%A Michael T Rowe
%J BMC Microbiology
%D 2006
%I BioMed Central
%R 10.1186/1471-2180-6-63
%X Between 4.6 and 9.1% of spiked populations of three Map strains (NCTC 8578, B2 and ATCC 19698), which had been added at a multiplicity of infection of 10:1, were ingested by Acanthamoeba castellanii CCAP 1501/1B and A. polyphaga CCAP 1501/3B during co-culture for 3 h at 25¡ãC. Map cells were observed to be present within the vacuoles of the amoebae by acid-fast staining. During extended co-culture of Map NCTC 8578 at 25¡ãC for 24 d with both A. castellanii and A. polyphaga Map numbers did not change significantly during the first 7 days of incubation, however a 1¨C1.5 log10 increase in Map numbers was observed between days 7 and 24 within both Acanthamoeba spp. Ingested Map cells were shown to be more resistant to chlorine inactivation than free Map. Exposure to 2 ¦Ìg/ml chlorine for 30 min resulted in a log10 reduction of 0.94 in ingested Map but a log10 reduction of 1.73 in free Map (p < 0.001).This study demonstrated that ingestion of Map by and survival and multiplication of Map within Acanthamoeba spp. is possible, and that Map cells ingested by amoebae are more resistant to inactivation by chlorine than free Map cells. These findings have implications with respect to the efficacy of chlorination applied to Map infected surface waters.Mycobacterium avium subsp. paratuberculosis (Map) is the known cause of Johne's disease of wild and domestic ruminants, in particular dairy cattle [1]. Although cattle are usually infected with Map during the first six months of life, via the faecal oral route, clinical signs, such as diarrhoea, emaciation and dehydration, usually develop only after a 3¨C5 year incubation period [2]. Despite the importance of Johne's disease, both from an animal welfare and agro-economic perspective, the molecular mechanisms that are involved in the entry and survival of Map in the host are only poorly characterised [3]. However, it is now generally accepted that the persistence of Map in host macrophages is crucial to the establishment and progression
%U http://www.biomedcentral.com/1471-2180/6/63