Metagenomic Approach to Characterizing Disease Epidemiology in a Disease-Endemic Environment in Northern Thailand

Takhampunya, Ratree; Korkusol, Achareeya; Pongpichit, Chalermpol; Yodin, Komsan; Rungrojn, Artharee; Chanarat, Nitima; Promsathaporn, Sommai; Monkanna, Taweesak; Thaloengsok, Sasikanya; Tippayachai, Bousaraporn; Kumfao, Naruemon; Richards, Allen L.; Davidson, Silas A.

In-house B. quintana IFA assay was prepared by CDC, Fort Collins (CO, United States) for testing the presence of human IgG against B. quintana. The protocol has been published previously (Iralu et al., 2006; Myint et al., 2011) . Briefly, the human serum (1:32 dilution) was added to a slide fixed with B. quintana antigen, prepared by infecting Vero E6 cells with the bacteria. The slide was then incubated in a moist chamber at 35 • C for 30 min, washed with PBS for 10 min, rinsed with distilled water, and air dried. Anti-human fluorescein isothiocyanate-labeled IgG conjugate was added to the slide which was processed as before. The slide was then mounted and read on a fluorescent microscope. All positive samples were then serially diluted in PBS, and an IFA-endpoint titer was determined using the same procedure; the end cut-off value for B. quintana was a titer greater than 1:200.