Avian Pneumovirus Key Info

Current Status

Avian pneumovirus (APV), also called turkey rhinotracheitis virus, is a newly emergent pathogen that causes upper respiratory tract disease in turkeys. Originally isolated in South Africa in 1978, APV was never detected in the USA until 1997 when simultaneous outbreaks occurred in the States of Colorado and Minnesota. Since then, APV has continued to be a problem primarily in Minnesota, even though few positive cases in commercial flocks have been reported in North Dakota, South Dakota, and Canada. The Minnesota turkey industry continues to suffer severe economic loss, estimated at 15 million dollars per year due to the disease. The losses are attributed to poor weight gain, mortality in cases of secondary bacterial and/or viral infection, and processing plant condemnation due to air sacculitis.

The clinical signs of APV disease include open mouth breathing, sneezing, gasping, coughing, ocular and nasal discharges, foamy conjunctivitis, and swelling of the infraorbital sinuses. In commercial flocks, weight loss and a drop in egg production are also observed. APV outbreaks show 100 % morbidity in susceptible flocks, and mortality, which is normally at 2-5%, can reach 30% in cases complicated by secondary bacterial and/or viral infection.

APV transmission is mainly by contact with infected birds, since virus shedding begins early after exposure, and continues throughout the period of clinical disease. Susceptible turkeys get infected through the upper respiratory track by aerosolization.

Analysis of the annual prevalence of APV outbreaks in commercial flocks in Minnesota revealed that approximately 80% of flock outbreaks occur in spring (April - May) and fall (October - December). This seasonal trend points to involvement of environment factors in the maintenance and spread of the virus. Consistent with this finding, infectious APV has recently been isolated in wild Canadian geese and viral RNA detected in wild ducks, geese, sparrows and swallows.

Research Goals

Research efforts in progress include the following:

1. Pathogenesis and immune response in APV infection.
2. Molecular characterization of emerging APV isolates in the US.
3. Evaluation of killed APV vaccine.
4. Completion of whole APV genome sequencing and generation of a deletion mutant vaccine.
5. Characterization of differential gene expression following APV infection in turkeys.
6. Evaluation of an avirulent goose APV isolate as a vaccine candidate.