Mosquito Bite Delivery of Dengue Virus Enhances Immunogenicity and Pathogenesis in Humanized Mice

Abstract

bDengue viruses (DENV) are transmitted to humans by the bite of Aedes aegypti or Aedes albopictus mosquitoes, with millions of infections annually in over 100 countries. The diseases they produce, which occur exclusively in humans, are dengue fever (DF) and dengue hemorrhagic fever (DHF). We previously developed a humanized mouse model of DF in which mice transplanted with human hematopoietic stem cells produced signs of DENV disease after injection with low-passage, wild-type isolates. Using these mice, but now allowing infected A. aegypti to transmit dengue virus during feeding, we observed signs of more severe disease (higher and more sustained viremia, erythema, and thrombocytopenia). Dengue fever (DF) in humans is characterized by fever, myalgia, arthralgia, abdominal pain, rash, low platelet counts (thrombocytopenia), and a viremia that begins 3 to 4 days after infection by mosquito bite. The more severe form of dengue, dengue hemorrhagic fever (DHF), usually presents as a second phase of disease, at the end of the fever stage, but with a sudden onset of plasma leakage that can result in hemoconcentration, pleural effusion, ascites, shock, hepatic failure, and encephalopathy. While this hemodynamic syndrome can resolve in 2 days, complete convalescence can take weeks to months (reviewed in reference 53). Moreover, ϳ5% of DHF patients die, usually from hypotensive shock, due to a delay in the recognition and treatment of the plasma leakage. Dengue virus (DENV)-induced disease has increased markedly due to the global spread of the virus and expansion of its mosquito vectors, and it is now the most important viral illness transmitted by insects (61). However, a clear understanding of the mechanisms leading to DF and DHF has been limited by several factors: (i) inadequate animal models of disease, with most knowledge being derived from clinical studies and in vitro experiments; (ii) the genetic diversity of DENV, with four different antigenic groups or serotypes and with humans potentially infected multiple times; and (iii) the relative risk of severe DENV disease, which is enhanced greatly by secondary infection with a heterologous serotype. The last factor has prompted the development of several models of immunopathogenesis (reviewed in reference 47) that have been difficult to evaluate experimentally, given the absence of reliable immunocompetent-animal models of human disease presenting with clinical signs of DHF after serial infection with wild-type viruses.We sought to produce an animal model of disease that could mimic the natural cycle of mosquito-human transmission with low-passage-number viruses from clinical samples, using human cells as targets of infection within a neutral background of nonsusceptible tissues (mouse) and using the appropriate species of mosquito vector, to evaluate the influence of biting/probing, virus delivery, and saliva proteins on DENV pathogenesis. Using humanized NOD/SCID/interleukin 2 receptor gamma (IL-2R␥)-null (hu-NSG) mice that had previously defined differences in th...

The Spleen: to Spleen or not to Spleen in Hematologic Diseases and in Vector Borne Hemoparasites

“…immune hemolytic anemia, immune thrombocytopenia (Gupta 2013;Cox 2012), and even cancer, which are life-threatening conditions if appropriate treatments are not soon issued (Kristinsson 2013;Hull 1988). et al, et al, et al, et al, …”

Infection via mosquito bite alters Zika virus replication kinetics in rhesus macaques

“…It is well established that mosquito transmission can affect arbovirus infection outcomes, but 237 outcomes vary depending on the mosquito-virus-host system 11,12,17,35 . In this study we found a 238 single sc dose of 1 x 10 4 PFU of ZIKV led to similar tissue distribution as observed in mosquito-239 inoculated animals at 15 dpi.…”

“…Subcutaneous inoculation, 264 by contrast, likely resulted in slower dissemination through the draining lymph nodes; 265 dissemination may be slower still following mosquito infection, as indicated by the delay in peak 266 viral loads observed with mosquito-bite delivery of virus in this study. In addition, the use of 267 multiple simultaneous injections 36 could iatrogenically cause disease signs 17 . For example, the 268 fever response observed with multiple injections might be expected, given that injection of virus 269 stocks also delivers cell culture medium components that might serve as irritants; needle 270 puncture of the skin is also more traumatic than insertion of a mosquito proboscis.…”

“…34 Pathogens such as ZIKV exploit this system to infect new vertebrate hosts. Mosquito saliva 35 enhances the replication and pathogenesis of numerous arthropod-borne viruses [16][17][18][19][20][21] . 36…”

“Current Dengue Vaccine Status”

“…The low dose ID route produced a higher percentage of tetravalent antibody seroconversion rates by PRNT compared to the high dose SQ route (71 % vs. 47 %) [42,43]. It is possible ID dosing more closely resembles mosquito delivery of virus, resulting in more efficient antigen processing, and therefore superior immunogenicity [44]. The majority (83 %) of subjects had detectable DENV-2 viral RNA after the first dose, but none had detectable viral RNA after the second dose [42].…”