Ante mortem diagnosis of human rabies using saliva samples: comparison of real time and conventional RT-PCR techniques.
BACKGROUND
Rabies is an enzootic and fatal disease and is still a major problem in developing countries. Ante mortem diagnosis in human cases is necessary for medical management of the patient and to ensure appropriate post-exposure treatment of contacts. Both conventional RT-PCR and Real time PCR (TaqMan) have been described for the detection of rabies virus RNA from saliva and tissue respectively, however to date, there have been no studies comparing conventional and real time PCR assays for detection of rabies virus nucleic acid using saliva samples for ante mortem diagnosis.


OBJECTIVE
In this study, we evaluated the utility of conventional RT-PCR and SYBR Green I Real time PCR in the ante mortem diagnosis of rabies using saliva samples.


METHODS
Saliva samples collected from twenty-four patients presenting with typical clinical manifestations of rabies were tested in the two assays.


RESULTS
Amongst the 24 samples tested, 21 samples (87.5%) were positive by either of the two molecular methods. Of these 21, rabies virus RNA was detected in 6/21 in the conventional RT-PCR assay while SYBR Green I Real time PCR could detect RNA in 18/21 samples.


CONCLUSIONS
Real time PCR assay was more sensitive than conventional RT-PCR assay (sensitivity 75% versus 37%, p=0.0189). This study highlights the utility of molecular diagnostic tests in establishing ante mortem diagnosis of rabies using saliva samples within a few hours.
Nagaraj
T
T
Department of Neurovirology, National Institute of Mental Health and Neurosciences, Bangalore 560029, India.
Vasanth
Joel P
JP
Desai
Anita
A
Kamat
Anupa
A
Madhusudana
S N
SN
Ravi
V
V
D000293:Adolescent; D000328:Adult; D000368:Aged; D052160:Benzothiazoles; D002648:Child; D002675:Child, Preschool; D003959:Diamines; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009930:Organic Chemicals; D016133:Polymerase Chain Reaction / Q000379:methods*; D011804:Quinolines; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D011818:Rabies / Q000175:diagnosis* / Q000821:virology; D011820:Rabies virus / Q000302:isolation & purification*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012463:Saliva / Q000821:virology
D052160:Benzothiazoles; D003959:Diamines; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D011804:Quinolines; D012367:RNA, Viral; C098022:SYBR Green I