Experimental Infection of a North American Raptor, American Kestrel (Falco sparverius), with Highly Pathogenic Avian Influenza Virus (H5N1)

Several species of wild raptors have been found in Eurasia infected with highly pathogenic avian influenza virus (HPAIV) subtype H5N1. Should HPAIV (H5N1) reach North America in migratory birds, species of raptors are at risk not only from environmental exposure, but also from consuming infected birds and carcasses. In this study we used American kestrels as a representative species of a North American raptor to examine the effects of HPAIV (H5N1) infection in terms of dose response, viral shedding, pathology, and survival. Our data showed that kestrels are highly susceptible to HPAIV (H5N1). All birds typically died or were euthanized due to severe neurologic disease within 4–5 days of inoculation and shed significant amounts of virus both orally and cloacally, regardless of dose administered. The most consistent microscopic lesions were necrosis in the brain and pancreas. This is the first experimental study of HPAIV infection in a North American raptor and highlights the potential risks to birds of prey if HPAIV (H5N1) is introduced into North America

Experimental challenge of a North American bat species, big brown bat (Eptesicus fuscus), with SARS-CoV-2

The recently emerged novel coronavirus, SARS-CoV-2, is phylogenetically related to bat coronaviruses (CoVs), specifically SARS-related CoVs from the Eurasian bat family Rhinolophidae. As this human pandemic virus has spread across the world, the potential impacts of SARS-CoV-2 on native North American bat populations are unknown, as is the ability of North American bats to serve as reservoirs or intermediate hosts able to transmit the virus to humans or to other animal species. To help determine the impacts of the pandemic virus on North American bat populations, we experimentally challenged big brown bats (Eptesicus fuscus) with SARS-CoV-2 under BSL-3 conditions. We inoculated the bats both oropharyngeally and nasally, and over the ensuing three weeks, we measured infectivity, pathology, virus concentrations in tissues, oral and rectal virus excretion, virus transmission, and clinical signs of disease. We found no evidence of SARS-CoV-2 infection in any examined bat, including no viral excretion, no transmission, no detectable virus in tissues, and no signs of disease or pathology. Based on our findings, it appears that big brown bats are resistant to infection with the SARS-CoV-2. The potential susceptibility of other North American bat species to SARS-CoV-2 remains to be investigated

Tissues from American kestrels experimentally inoculated with highly pathogenic avian influenza virus H5N1.

<p>A. Pancreas with multifocal to coalescing areas of necrosis (arrows) (HE stain). B. Brain with multifocal cerebral necrosis (arrows) accompanied by a mild infiltration of heterophils (HE stain). C. Section of same pancreatic tissue as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0007555#pone-0007555-g002" target="_blank">Fig. 2A</a>, stained by immunohistochemistry to identify influenza A virus antigen. Staining of influenza A antigen is intense in areas of necrosis (arrows). D. Immunohistochemical staining of influenza A virus antigen in brain tissue. Areas of brain necrosis are strongly positive (arrows).</p

Oral shedding of highly pathogenic avian influenza virus H5N1 by experimentally.

1<p>Inoculation dose (log₁₀ EID_50/0.1 mL).</p>2<p>nc =  no Ct value obtained by H5 subtype specific RT-PCR analysis and confirmed in embryonated egg culture.</p>3<p>Virus amounts represented as RT-PCR Ct values.</p>4<p>Numbers in parentheses represent viral titers (log10 EID₅₀/0.1 mL) as determined in embryonated egg culture.</p><p>*Presence of infectious virus confirmed by virus isolation in embryonated eggs.</p

Survival of American kestrels infected with highly pathogenic avian influenza virus H5N1.

<p>Daily percentage of American kestrels surviving after infection with one of three doses of highly pathogenic avian influenza virus H5N1 (A/whooperswan/Mongolia/244/05).</p

Cloacal shedding of highly pathogenic avian influenza virus H5N1 by experimentally.

1<p>Inoculation dose (log₁₀ EID_50/0.1 mL).</p>2<p>nc =  no Ct value obtained by H5 subtype specific RT-PCR analysis and confirmed in embryonated egg culture.</p>3<p>Virus amounts represented RT-PCR Ct values.</p>4<p>Numbers in parentheses represent viral titers (log10 EID50/0.1 mL) as determined in embryonated egg culture.</p><p>*Presence of infectious virus confirmed by virus isolation in embryonated eggs.</p

Sampling locations of sea ducks in the North Atlantic region.

<p>Sampling locations of sea ducks in the North Atlantic region.</p

Figure 2

<p>A. Map showing position of Iceland relative to the East Atlantic Flyway (red arrows) and the North American Atlantic Flyway (yellow arrows). Flyways represent generalized migration movements of birds with most using only portions of the flyways. Actual regions of flyways used by migratory birds are dependent on species and breeding population. B. Map of Iceland depicting bird sampling locations (red dots) used in this study and Reykjavik (red star) is provided for reference. Breiðafjörður and Selfoss sampling locations are generalized as samples provided by hunters and fisherman were obtained over a larger area within these marked regions.</p

Viruses recovered from Iceland wild birds in 2010–2011 with segment lineage detail.

<p>EU denotes the segment is most similar to Eurasian lineage viruses, AM denotes the segment is most similar to American lineage viruses. Within each segment column, segments that have the same color indicate a ≥99% nucleotide sequence similarity among that segment. * indicates a ≥99% similarity to only one other virus segment of the same color denoted by †. Bold text indicates novel virus assemblages.</p