Development and validation of 2 probe-hybridization quantitative PCR assays for rapid detection of a pathogenic Coxiella species in captive psittacines

J Vet Diagn Invest. 2020 May;32(3):423-428. doi: 10.1177/1040638720912221. Epub 2020 Mar 19.

Abstract

Avian coxiellosis is an emerging cause of morbidity and mortality among captive psittacines, and the utility of a rapid detection test using easily obtained samples is paramount in a clinical setting. New sequences were obtained from 3 genes: groEL, dnaK, and rpoB. We developed probe-hybridization quantitative PCR (qPCR) assays using groEL and dnaK genes. Samples, including splenic aspirates, liver aspirates, whole blood, and choanal, conjunctival, and cloacal swabs, were collected from 4 psittacine species including 3 blue-and-gold macaws (Ara ararauna), 2 scarlet-chested parrots (Neophema splendida), 1 Timneh African grey parrot (Psittacus timneh), and 1 yellow-naped Amazon parrot (Amazona auropalliata). Retrospective review of postmortem findings from 3 of these psittacines included splenomegaly, hepatitis, and/or transmission electron microscopy confirmation consistent with previous reports of avian coxiellosis. There was 100% agreement between these assays and consensus PCR with sequencing. A Wilcoxon rank-sum test found a strong correlation between groEL and dnaK cycle threshold values (p < 0.001), validating these assays for detection of this avian Coxiella sp.

Keywords: Coxiella; birds; parrots; quantitative PCR.

MeSH terms

  • Amazona
  • Animals
  • Bird Diseases / microbiology*
  • Bird Diseases / pathology
  • Coxiella / classification
  • Coxiella / isolation & purification*
  • Gram-Negative Bacterial Infections / microbiology
  • Gram-Negative Bacterial Infections / veterinary*
  • Parrots*
  • Real-Time Polymerase Chain Reaction / methods
  • Real-Time Polymerase Chain Reaction / veterinary*
  • Retrospective Studies