PCR-Based Detection of an Emerging Avian Pneumovirus in US Turkey Flocks

Abstract

Abstract. Avian pneumovirus (APV) or turkey rhinotracheitis virus (TRTV) is an important respiratory pathogen of domesticated poultry in many countries in Europe, Africa, and Asia. Until recently, the United States was considered free of APV. In late 1996, an atypical upper respiratory tract infection appeared in turkey flocks in Colorado and shortly thereafter in turkey flocks in Minnesota. An avian pneumovirus (APV-US) that was serologically distinct from the previously described TRTV was isolated as the primary cause of the new syndrome. The nucleotide sequence of a fragment of the APV-US fusion gene was determined and used to develop a polymerase chain reaction-based assay that specifically detects APV-US viral nucleic acid sequences in RNA extracts of tracheal swabs and turbinate homogenates. The assay is highly sensitive in that it can detect Ͻ0.01 TCID 50 of APV. The availability of this assay enables the rapid and accurate determination of APV-US in infected poultry flocks.

Experimental and field evaluation of a live vaccine against avian pneumovirus

“…A few flocks from the neighbourin g states of North and South Dakota have also been found to be serologically positive for APV infection (Lauer, 2000). A similar disease is present in European turkeys, but the US isolates of APV have been shown to differ antigenically and genetically from the A and B subtypes of European APV (Seal, 1998;Panigrahy et al, 2000;Seal et al, 2000;Dar et al, 2001). Recently, a subgroup D strain of APV has been reported (Bäyon-Auboyer et al, 2000).…”

Growth of vaccine strains of avian pneumovirus in different cell lines

“…The virus causes upper respiratory tract infection in turkeys and chickens of all ages and is prevalent worldwide as indicated by serological testing (Jones, 1996). Existing APV strains have been classified into four subgroups, namely subgroups A, B, C, and D. Subgroup C is prevalent in the US (Seal, 1998;Seal et al ., 2000;Dar et al ., 2001) while subgroups A, B, and D are found mainly in Europe (Cook & Cavanagh, 2002). The subgroup C of APV was isolated initially by inoculation of samples in chicken embryo fibroblast cultures followed by adaptation of the virus isolate in Vero cells (Goyal et al ., 2000).…”

A Modified Enzyme-Linked Immunosorbent Assay for the Detection of Avian Pneumovirus Antibodies

“…It is possible that NP-40 extraction may enrich the external viral proteins, whereas freeze/thaw treatment may enrich internal components of the virus. Discrepancies in TRTV ELISA results with different antigens have been reported 6 and it has been suggested that the efficiency of serological testing may improve if the test uses antigens prepared from virus strains originating from different geographical areas.…”

“…17 Although the Colorado and Minnesota isolates of APV are similar to TRTV antigenically, major differences have been found among them. 6 This study reports on the detection of antibodies to APV infection in Minnesota turkeys.…”

“…The detection of TRTV antibodies, on the other hand, may be more rapid and economical when compared with virus isolation and reverse transcriptase-polymerase chain reaction. 6,12 Serum antibodies to TRTV have been detected by indirect immunofluorescence assay (IFA), virus neutralization, and enzyme-linked immunosorbent assay (ELISA). 3,7,9,10,16,118 Outbreaks of avian pneumovirus (APV) infection were reported in Minnesota turkeys for the first time in March 1997.…”