J Infect Dis. 2017 Jan 1;215(1):70-79. doi: 10.1093/infdis/jiw499. Ep

Humanized Mice Reproduce Acute and Persistent Human Adenovirus Infection.

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Humanized mice are useful tools to study human-specific diseases in a human context. They have been widely used to study cancer, autoimmune diseases, hematopoietic stem cell transplantation and infectious diseases. The use of humanized mice to model human viral infections, has been classically limited to HIV. Only in the last years, models have been established for other viruses like Epstein-Barr virus (EBV) [1], Ebola [2], and Dengue virus [3-6].

 

Human Adenoviruses (HAdV) usually cause asymptomatic to mild infections of the upper respiratory tract, gastrointestinal tract and conjunctiva. These infections are self-limited for the majority of the population; however, in immune-compromised patients that undergo stem cell transplantation, and especially, in children, HAdV causes life-threatening infections [7-14]. It is thought that these infections are a consequence of the reactivation of a HAdV persistent infection. Whether the virus comes from the donor bone marrow or from the recipient still remains unknown.

 

It has been widely studied that HAdV can persistent in tonsils, adenoids and lymphocytes of the gastro-intestinal tract [15-20]; however, little is known about he mechanisms of viral persistence and reactivation. Although several studies have used cultured cell lines to model HAdV persistence [21, 22], there are no good in vivo models that would mimic HAdV persistence and pathogenesis because HAdVs are highly species-specific, meaning that they can only infect human cells.

 

In our recent publication, we have shown the establishment of a humanized mouse model for HAdV infections. We generated these animals using NSG mice that express human HLA-A2, which were then transplanted with HLA-matching human hematopoietic stem cells (HSC) isolated from umbilical cord blood. This allows for the reconstitution of a broad range of blood cell subpopulations, including mature T-cells.

 

 

Infection of these animals with HAdV-C2, which is the most commonly HAdV strain found in immune-compromised patients, induced two different phenotypes (Fig. 1). On one hand, one third of the animals developed acute infection, shown by progressive weight loss, ruffled fur and lethargy. These physical symptoms were a consequence of an Adenovirus-induced hepatitis, which was shown by the presence of liver steatosis (Fig. 2), hepatocyte vacuolization, fibrosis and infiltration of human immune cells (Fig. 2), specially, of monocytes and macrophages. In these animals, viral mRNAs were detected in several organs, and both early and late viral proteins were found in the liver. Furthermore, animals showed virus dissemination as infectious particles could be rescued from the liver and peripheral blood. On the other hand, the rest of the animals remained asymptomatic, however, some of them, had developed an Adenovirus persistent infection in the bone marrow. This was shown by the presence of early viral mRNAs in this body site, however, no viral proteins or late mRNAs were found in any organ assayed. In line with this, no infectious virus could be rescued from these animals. These results indicated that HAdV had induced a persistent/latent infection in the bone marrow of humanized mice.

 

 

Additionally, our model showed establishment of primary and adaptive immune responses that served us to distinguish between acute and persistent infection.

 

The importance of our findings lies in the fact that a species-specific virus like HAdV is able to cause a phenotype in humanized mice, where only immune cells are human, suggesting that the immune system plays a crucial role in the pathogenesis of severe HAdV infections. We do not know yet why some animals develop acute infection and others don’t. More experiments are needed to understand which blood cell subpopulations are important for fighting these infections, which might be missing in some of our animals and also in stem cell transplanted patients that develop severe HAdV infections. The fact that a HAdV persistent infection could be found only in the bone marrow among all the other humanized hematopoietic organs in our mice, suggest that this body site might be the place for viral persistence. Intriguingly, the presence of HAdV in bone marrow donors is not routinely checked, in contrast to HIV and Hepatitis C. Further experiments are needed to prove whether a similar reservoir exists in human subjects and measures must be taken to screen for the presence of HAdV in the bone marrow of donors.

 

References

  1. Yajima M, Imadome K, Nakagawa A, et al. A new humanized mouse model of Epstein-Barr virus infection that reproduces persistent infection, lymphoproliferative disorder, and cell-mediated and humoral immune responses. J Infect Dis 2008; 198:673-82.
  2. Ludtke A, Oestereich L, Ruibal P, et al. Ebola virus disease in mice with transplanted human hematopoietic stem cells. J Virol 2015; 89:4700-4.
  3. Bente DA, Melkus MW, Garcia JV, Rico-Hesse R. Dengue fever in humanized NOD/SCID mice. J Virol 2005; 79:13797-9.
  4. Jaiswal S, Pearson T, Friberg H, et al. Dengue virus infection and virus-specific HLA-A2 restricted immune responses in humanized NOD-scid IL2rgammanull mice. PLoS One 2009; 4:e7251.
  5. Jaiswal S, Pazoles P, Woda M, et al. Enhanced humoral and HLA-A2-restricted dengue virus-specific T-cell responses in humanized BLT NSG mice. Immunology 2012; 136:334-43.
  6. Jaiswal S, Smith K, Ramirez A, et al. Dengue virus infection induces broadly cross-reactive human IgM antibodies that recognize intact virions in humanized BLT-NSG mice. Exp Biol Med (Maywood) 2015; 240:67-78.
  7. Flomenberg P, Babbitt J, Drobyski WR, et al. Increasing incidence of adenovirus disease in bone marrow transplant recipients. J Infect Dis 1994; 169:775-81.
  8. Lion T, Baumgartinger R, Watzinger F, et al. Molecular monitoring of adenovirus in peripheral blood after allogeneic bone marrow transplantation permits early diagnosis of disseminated disease. Blood 2003; 102:1114-20.
  9. Walls T, Shankar AG, Shingadia D. Adenovirus: an increasingly important pathogen in paediatric bone marrow transplant patients. Lancet Infect Dis 2003; 3:79-86.
  10. Ljungman P. Treatment of adenovirus infections in the immunocompromised host. Eur J Clin Microbiol Infect Dis 2004; 23:583-8.
  11. Chakrabarti S. Adenovirus infections after hematopoietic stem cell transplantation: still unravelling the story. Clin Infect Dis 2007; 45:966-8.
  12. Feuchtinger T, Lang P, Handgretinger R. Adenovirus infection after allogeneic stem cell transplantation. Leuk Lymphoma 2007; 48:244-55.
  13. Fowler CJ, Dunlap J, Troyer D, Stenzel P, Epner E, Maziarz RT. Life-threatening adenovirus infections in the setting of the immunocompromised allogeneic stem cell transplant patients. Adv Hematol 2010; 2010:601548.
  14. Lion T. Adenovirus infections in immunocompetent and immunocompromised patients. Clin Microbiol Rev 2014; 27:441-62.
  15. van der Veen J, Lambriex M. Relationship of adenovirus to lymphocytes in naturally infected human tonsils and adenoids. Infect Immun 1973; 7:604-9.
  16. Andiman WA, Miller G. Persistent infection with adenovirus types 5 and 6 in lymphoid cells from humans and woolly monkeys. J Infect Dis 1982; 145:83-8.
  17. Garnett CT, Erdman D, Xu W, Gooding LR. Prevalence and quantitation of species C adenovirus DNA in human mucosal lymphocytes. J Virol 2002; 76:10608-16.
  18. Garnett CT, Talekar G, Mahr JA, et al. Latent species C adenoviruses in human tonsil tissues. J Virol 2009; 83:2417-28.
  19. Roy S, Calcedo R, Medina-Jaszek A, Keough M, Peng H, Wilson JM. Adenoviruses in lymphocytes of the human gastro-intestinal tract. PLoS One 2011; 6:e24859.
  20. Kosulin K, Geiger E, Vecsei A, et al. Persistence and reactivation of human adenoviruses in the gastrointestinal tract. Clin Microbiol Infect 2016; 22:381 e1-8.
  21. Chu Y, Sperber K, Mayer L, Hsu MT. Persistent infection of human adenovirus type 5 in human monocyte cell lines. Virology 1992; 188:793-800.
  22. Zhang Y, Huang W, Ornelles DA, Gooding LR. Modeling adenovirus latency in human lymphocyte cell lines. J Virol 2010; 84:8799-810.