A Human Lung Xenograft Mouse Model of Nipah Virus Infection

Abstract

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 molecular mechanisms of NiV-associated ALI in the human respiratory tract are unknown. Thus, there is an urgent need for models of henipavirus infection of the human respiratory tract to study the pathogenesis and understand the host responses. Here, we describe a novel human lung xenograft model in mice to study the pathogenesis of NiV. Following transplantation, human fetal lung xenografts rapidly graft and develop mature structures of adult lungs including cartilage, vascular vessels, ciliated pseudostratified columnar epithelium, and primitive “air” spaces filled with mucus and lined by cuboidal to flat epithelium. Following infection, NiV grows to high titers (107 TCID50/gram lung tissue) as early as 3 days post infection (pi). NiV targets both the endothelium as well as respiratory epithelium in the human lung tissues, and results in syncytia formation. NiV infection in the human lung results in the production of several cytokines and chemokines including IL-6, IP-10, eotaxin, G-CSF and GM-CSF on days 5 and 7 pi. In conclusion, this study demonstrates that NiV can replicate to high titers in a novel in vivo model of the human respiratory tract, resulting in a robust inflammatory response, which is known to be associated with ALI. This model will facilitate progress in the fundamental understanding of henipavirus pathogenesis and virus-host interactions; it will also provide biologically relevant models for other respiratory viruses.

Contribution of Human Lung Parenchyma and Leukocyte Influx to Oxidative Stress and Immune System-Mediated Pathology following Nipah Virus Infection

“…Similarly, the reconstitution levels, prior to challenge, in mice with tissues from donor 2 that were scheduled to be euthanized on days 3 and 5 averaged 40.2% and 34.1%, respectively ( Table 1). As previously shown (15), the lung grafts implanted on the 44 mice displayed similar structures of the lower respiratory tract and some of the typical differentiated cells, including ciliated and alveolar-like cells, as in the normal human lung.…”

“…These features were also found in NiV-Minfected human lung xenografts (15) and in lungs of several animal models, such as Syrian hamsters, ferrets, and African Green monkeys (10,13,(16)(17)(18), demonstrating the suitability of these models for the study of NiV pathogenesis. Previously, we demonstrated in vitro that NiV-B infection of primary human small airway epithelial cells caused a strong inflammatory response, in part induced by oxidative stress (19), that was accompanied by cell damage and chemotaxis of mononuclear cells (12,20).…”

“…These mice are referred as reconstituted mice in this study. (Right) Human lung graft model in NSG mice, as previously described (15), that did not undergo human immune system reconstitution. These mice were named nonreconstituted mice in this study.…”

“…lung grafts from donors 1 and 2 were pooled, as no significant differences in any of the parameters analyzed were observed throughout the study. Assessment of NiV-B titers in lung grafts was done at days 3 and 5 p.i., based on results from our previous study (15) that validated this endpoint as being optimum. NiV-B titers increased by 2 log 10 units over the course of infection in lung grafts regardless of the reconstitution status of the mice (Fig.…”

“…These models reconstitute the microenvironment of the human lung to evaluate the host response during virus infection in the human lung. First, our group recently developed a novel xenograft model of the human respiratory tract, allowing us to study in vivo NiV pathogenesis in human lung grafts lacking human immune cells (15). Here, we build on this model and characterized NiV-B pathogenesis in human lung grafts in the presence of the human immune system in mice using the bone marrow, liver, and thymus (BLT) reconstitution method (23), which allows peripheral and resident immune cells to respond to infection of lung grafts, as in NiV-infected patients.…”