Oxidative stress in Nipah virus-infected human small airway epithelial cells

Nipah virus (NiV) is a zoonotic emerging pathogen that can cause severe and often fatal respiratory disease in humans. The pathogenesis of NiV infection of the human respiratory tract remains unknown. Reactive oxygen species (ROS) produced by airway epithelial cells in response to viral infections contribute to lung injury by inducing inflammation and oxidative stress; however, the role of ROS in NiV-induced respiratory disease is unknown. To investigate whethe

A Human Lung Xenograft Mouse Model of Nipah Virus Infection

Nipah virus (NiV) is a member of the genus Henipavirus (family Paramyxoviridae) that causes severe and often lethal respiratory illness and encephalitis in humans with high mortality rates (up to 92%). NiV can cause Acute Lung Injury (ALI) in humans, and human-to-human transmission has been observed in recent outbreaks of NiV. While the exact route of transmission to humans is not known, we have previously shown that NiV can efficiently infect human respiratory epithelial cells. The molecu

Histopathological changes during Nipah virus infection in human lung xenografts.

<p>Human lung sections were stained with H&E as described in Experimental Procedures. (A) Human lung with focal areas of necrosis and syncytia formation (black arrow) on day 3 post infection (10× magnification). (B) Human lung with extensive areas of necrosis, syncytia formation and loss of architecture on day 10 post infection (10× magnification). (C) Bronchi with syncytia formation (*) on day 3 post infection (20× magnification). (D) Loss of alveolar architecture and areas of necrosis (black arrow) on day 10 post infection (20× magnification). (E) Alveolar space with syncytial formation (*) on day 3 post infection (40× magnification). (F) Pulmonary vasculature with syncytial formation (*) on day 3 post infection (40× magnification), fibrinoid necrosis of the intima, and influx of granulocytes (black arrowhead). Data are representative from 6 tissues per animal, 3 animals per time point.</p

Histological characterization of human lung xenografts.

<p>Normal (A) and xenograft (B–F) human lung sections were stained with H&E as described in Experimental Procedures. Following transplantation, human lung xenografts develop mature structures (B) similar to those seen in normal human lung (A)(10× magnification). Structures include pseudostratified ciliated epithelium (C) (40× magnification), terminal bronchioles (D) (10× magnification), alveolar spaces (E)(40× magnification) and pulmonary vasculature (F)(10× magnification). Ephrin B2 expression was observed in normal human lung (red) (G) and human lung xenograft tissues (yellow) (H) with similar distribution on epithelium (10× magnification). Br = bronchi, V = pulmonary vasculature, Av = alveoli, Ca = cartilage, Ci = cilia, Pe = pseudostratified epithelium, Ef = elastic fibers, Tb = terminal bronchiole.</p

Summary of virological and histological findings in human lung graft, mouse tissues and blood following Nipah virus challenge.

<p>N/A = Not applicable. Direct = injection into the graft, resulting in primary infection; Indirect = secondary infection resulting from virus dissemination from the direct infected lung graft. IP = Intraperitoneal challenge. SC = Subcutaneous challenge. Infectious virus was determined in human lung and mouse tiisues and whole blood by TCID_50% as described in Materials & Methods. Viral antigen was detected with an anti N antibody as described in Materials & Methods. Histopathology is based on H&E stained lung sections described in Materials & Methods.</p><p>* = data available on day 10 post infection only.</p>#<p> = for control NSG mice only.</p><p>+++ = high virus titer/intense immunostaining/extensive histopathological changes. + = low virus titer/low intensity immunostaining, − = not detected.</p

Nipah virus tropism in human lung xenografts.

<p>Lung sections were stained by immunohistochemical (IHC) detection of Nipah virus nucleoprotein as described in Experimental Procedures. An overview of viral antigen distribution is shown on day 3 (A) and day 10(B) post infection (10× magnification). (C) Bronchial epithelium positive for NiV antigen in a syncytium (black arrow) on day 3 post infection (40× magnification). (D) Alveolar space with NiV positive cell, primarily cuboidal morphology on day 3 post infection (40× magnification). (E) Pulmonary vasculature positive for NiV antigen on day 3 post infection (40× magnification). (F) Small focal area in mouse lung tissue positive for NiV antigen (red) on day 10 post infection (10× magnification)(nuclei in blue). Br = bronchi, V = pulmonary vasculature. T2 = Type 2 pneumocyte. Data are representative from 3 animals per time point.</p

Nipah virus replication in human lung xenografts.

<p>Virus replication was determined in human lung (A) and mouse (B) tissues at days 1, 3, 5, 7 and 10 post infection by virus titration. Titers were determined in human lung following primary (direct injection) or secondary (infection due to viremia). Samples from three animals were assayed and analyzed and the mean titers were calculated as TCID₅₀/gram tissue. The error bars represent the standard deviation.</p

Cytokine levels in Nipah virus infected human lung xenografts.

<p>The concentrations of cytokines were determined in lung homogenates of human lung xenografts following direct infection with NiV as described in the Experimental Procedures. Concentrations are expressed as picogram (pg) cytokine per gram lung tissue. The error bars represent the standard deviation.</p

Cell tropism of Nipah virus in human lung xenografts.

<p>Lung sections were stained by immunofluorescent detection of Nipah virus nucleoprotein (red), CD31 (green) and nucleus (blue) as described in Experimental Procedures. (A) Human lung showing focal area of Nipah virus distinct from pulmonary vasculature on day 3 post infection (10× magnification). (B) CD31 positive endothelium of pulmonary vasculature is positive for Nipah virus antigen (40× magnification). Data are representative from 3 animals per time point.</p