Immunopathological immunohistochemical study of low pathogenic avian influenza virus H5N1 infection in lovebirds (Agapornis spp.) in Indonesia

BACKGROUND AND AIM: To date, persistent infection with low pathogenic avian influenza virus (AIV) subtype H5N1 (LPAI H5N1) in chickens is widespread in Indonesia. Commercially available ornamental birds on markets play an important role in triggering the occurrence of AIV outbreaks. Thus, the presence of AIV in ornamental birds such as lovebirds needs to be closely monitored. Here, the presence of LPAI H5N1 was investigated in lovebirds with no clinical signs that, although apparently healthy, can be a continuous source of AIV transmission to other sensitive birds such as chickens and even humans. MATERIALS AND METHODS: In the present study, 30 lovebirds were necropsied. The immunopathology of the lungs, which had hemorrhages, was immunohistochemically studied using the streptavidin-biotin (SB) method to stain for LPAI H5N1. Polyclonal antibodies against the nucleoprotein or monoclonal antibodies against the hemagglutinin of the AIV subtype H5N1 were used to identify these antigens in lung tissue samples. RESULTS: LPAI H5N1 was detected in the lungs of all lovebirds according to the brownish colored deposits in the histological samples. The highest intensity of the SB staining was found in the lumina of vascular capillaries and the cell membranes of air capillaries. The discovery of LPAI H5N1 in lovebirds increases the environmental health risk and raises the possibility of exposure to AIV. Thus, it is very important to improve the mechanisms that control the traffic of ornamental birds between regions and islands, as well as the AIV vaccination strategies related to the prevention, control, and eradication of AIV in Indonesia, and these procedures should be reevaluated. CONCLUSION: The present study proves that lovebirds are infected with LPAI subtype H5N1. Even if ornamental birds such as lovebirds do not show any clinical signs, they are likely to be a persistently infected with LPAI H5N1. Therefore, ornamental birds might be a continuous source of LPAI H5N1 infections in other sensitive birds, including poultry, and may also be responsible for virus transmission to humans.