Visual detection of goose haemorrhagic polyomavirus in geese and ducks by loop-mediated isothermal amplification.

Goose haemorrhagic polyomavirus (GHPV) is an aetiological agent of haemorrhagic nephritis and enteritis of geese occurring in geese (Anser anser). GHPV may also infect Muscovy ducks (Carina mochata) and mule ducks. Early detection of GHPV is important to isolate the infected birds from the rest of the flock thus limiting infection transmission. The current diagnosis of haemorrhagic nephritis and enteritis of geese is based on virus isolation, histopathological examination, haemagglutination inhibition assay, ELISA and polymerase chain reaction (PCR). Recently, real-time PCR assay was developed which considerably improved detection of GHPV. In spite of many advantages, these methods are still time-consuming and inaccessible for laboratories with limited access to ELISA plate readers or PCR thermocyclers. The aim of our study was to develop loop-mediated isothermal amplification (LAMP) that may be conducted in a water bath. Two pairs of specific primers complementary to VP1 gene of GHPV were designed. The results of GHPV LAMP were recorded under ultraviolet light. Our study showed LAMP was able to specifically amplify VP1 fragment of a GHPV without cross-reactivity with other pathogens of geese and ducks. LAMP detected as little as 1.5 pg of DNA extracted from a GHPV standard strain (150 pg/µl). The optimized LAMP was used to examine 18 field specimens collected from dead and clinically diseased geese and ducks aged from 1 to 12 weeks. The positive signal for GHPV was detected in three out of 18 (16.6%) specimens. These results were reproducible and consistent with those of four real-time PCR. To the best of our knowledge this is the first report on LAMP application for the GHPV detection.