Chapter VI Molecular tests and evaluation of results

The current definition of HPAI, allows the molecular identification of virulence factors and confirms the use of molecular techniques in the diagnosis of AI. Recently there have been developments in their application for detection and characterisation of AI virus directly from clinical specimens from infected birds. Conventional RT-PCR techniques on clinical specimens could, with the correctly defined primers, result in rapid detection and subtype (at least of H5 and H7) identification, plus a PCR amplicon product that could be used for nucleotide sequencing and have been demonstrated to have an important application by rapidly identifying subsequent outbreaks once the primary infected premises has been detected and the virus characterised. ‘Real time’ single-step RT-PCR using primer/fluorogenic probe systems (rRT-PCR) allow even more rapid and sensitive diagnosis with detection of AI viruses and determination of subtype H5 or H7 in clinical samples.

F1The Weybridge National Reference Laboratory has produced protocols for molecular tests including conventional RT-PCR and rRT-PCR to be followed as standard. If test parameters, such as cycling and ramp times, are varied from those recommended in the specified protocols they must be demonstrated to be consistent with paragraph 6 of Chapter I of this diagnostic manual prior to use.