Cell culture may be more cost-effective and time-efficient than the use of embryonated eggs or animal inoculation. Continuous cell lines such as Vero and L929 cells are useful for growing C. burnetii (Burton et al., 1978). Infection does not generally destroy the host cell line, and infected cells have the same cell cycle progression as uninfected cells. This is a result of asymmetric division of infected cells producing one infected and one uninfected daughter cell. This ability of C. burnetii

has allowed it to persistently infect cell cultures for over 2 years without the addition of uninfected cells (Roman et al., 1986). Amoeba (Acanthamoeba castellanii) have also been shown to Selleck Alectinib maintain C. burnetii infection (La Scola & Raoult, 2001). Four cell lines (Vero, L929, DH82, and XTC-2) were used in this study and compared for their ability to amplify very low numbers of C. burnetii. Previous studies have

shown that different cell lines have different levels of sensitivity to C. burnetii infection (Rumin et al., 1990). Two different www.selleckchem.com/products/U0126.html isolates of C. burnetii were used in this comparative study of four different cell lines as it has been shown that different strains have different pathogenicities (Stoenner & Lackman, 1960). These were the Henzerling strain (as used in the Australian vaccine Qvax, originally isolated in Italy) and the recent Australian isolate ‘Arandale’ (isolated from a human case of acute Q-fever). It has been shown that both phase I and phase II cells can persistently infect cell cultures (Baca et al., 1985), but phase I cells revert to phase II during cell passages. It may be possible that cell lines

have different sensitivities to C. burnetii isolates from different genomic groups. It has been found that ‘acute’ isolates (with plasmid QpH1) and ‘chronic’ isolates (with no plasmid) infected cells more readily and caused an increased amount of C. burnetii antigen to be displayed on the host cell membrane compared to other isolates also implicated in chronic Q-fever (such as Priscilla Q177 and F Q228, both with the plasmid QpRS) (Roman et al., 1991). Tenfold dilutions were made from a suspension Phosphatidylinositol diacylglycerol-lyase of both C. burnetii isolates. The starting material for the Henzerling isolate was a homogenate of infected egg yolk sack (courtesy of Commonwealth Serum Laboratories, Australia). The starting material for the ‘Arandale’ isolate was a homogenate of spleen from infected severe combined immunodeficient (SCID) mice. Tenfold dilutions of each starting material were made in Hanks’ balanced salt solution (HBSS; Gibco, Australia). The actual dilutions of the C. burnetii suspensions selected to inoculate into cell culture were based on preliminary testing (data not shown). All experiments with C. burnetii were carried out in a biocontainment level 3 laboratory at the Department of Microbiology, John Hunter Hospital, Newcastle.