Rickettsiales and rickettsial diseases in Australia - Murdoch ...

development of highly specific, sensitive and rapid assays for detection of
Rickettsiales in many different samples including blood, tissue and arthropods 77,
78 . The key advantage to this assay is its speed, as it can be performed in one
day.
1.5.4.1. Conventional PCR
The first PCR to detect Rickettsia was published in 1989 and targeted the
17kDa gene (orf17) 255 . Since then, assays have been developed that target a
number of rickettsial genes. These include the 16S rRNA gene (rrs) 216 , citrate
synthase gene (gltA) 218 , OmpA gene (rompA) 82 , OmpB gene (rompB) 217 and
gene D (sca4) 223 . Assays targeting the 16S rRNA gene 169 , 22kD, 47kD, 110kD,
groESL and 56kD genes for Orientia tsutsugamushi have also been
designed 128 . Assays have also been developed that amplify various genes
including the 16S rRNA, groESL, surface protein 66 , citrate synthase 115 , msp2 64
and “dsb” genes 63 of the family Anaplasmataceae.
1.5.4.2. Real-time PCR (qPCR)
Real time PCR (qPCR) involves the use of a fluorescent probe to detect the
amplification of target DNA as it occurs. One common method used for
rickettsial identification is the TaqMan probe method 105 . This method has been
successfully used to detect members of the Anaplasmataceae 196 and
Rickettsiaceae 122 families. This is considered one of the most sensitive and
specific assays and is the fastest way to diagnose an infection. Therefore it is
often the molecular method of choice.
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