Phenotypic characterization of patient dengue virus isolates in BALB/c mice differentiates dengue fever and dengue hemorrhagic fever from dengue shock syndrome

Abstract

BackgroundDengue virus (DENV) infection is the most common arthropod-borne viral disease in man and there are approximately 100 million infections annually. Despite the global burden of DENV infections many important questions regarding DENV pathogenesis remain unaddressed due to the lack of appropriate animal models of infection and disease. A major problem is the fact that no non-human species naturally develop disease similar to human dengue fever (DF) or dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Apart from other risk factors for severe dengue such as host genetics and secondary infection with a heterologous DENV, virus virulence is a risk factor that is not well characterized.ResultsThree clinical DENV-1 isolates from Cambodian patients experiencing the various forms of dengue disease (DF, DHF, and DSS) were inoculated in BALB/c mice at three different concentrations. The DENV-1 isolates had different organ and cell tropism and replication kinetics. The DENV-1 isolate from a DSS patient infected the largest number of mice and was primarily neurotropic. In contrast, the DENV-1 isolates from milder clinical dengue cases infected predominantly lungs and liver, and to a lesser extent brain. In addition, infection with the DENV isolate derived from a DSS patient persisted for more than two weeks in a majority of mice compared to the other DENV-1 isolates that peaked during the first week.ConclusionsThese results confirm the in vitro findings of the same DENV-1 isolates, that showed that the isolate derived from a DSS patient can be distinguished based on phenotypic characteristics that differ from the isolates derived from a DF and DHF case [1]. We observed in this study that the DSS virus isolate persist longer in vivo with extensive neuroinvasion in contrast to the other DENV-1 isolates originating in milder human cases. Genomic characterization of the three clinical isolates identified six amino acid substitutions unique for the DSS isolates that were located both in structural genes (M and E) and in non-structural genes (NS1, NS3, and NS5). The characterization of these clinically distinct DENV-1 isolates highlight that DENVs within the same genotype may have different in vivo phenotypes.Highlights• Clinical DENV-1 isolates have different organ tropism in BALB/c mice.• The isolate from a DSS patient is primarily neurotropic compared to the other isolates.• The DENV-1 isolates have different in vivo replication kinetics.• The isolate from a DSS patient persists longer compared to the other isolates.• These phenotypic differences confirm our earlier in vitro findings with the same DENV-1 isolates. Thus, DENVs within the same serotype and genotype may differ enough to affect clinical conditions in vivo.

The Bama miniature swine is susceptible to experimental HEV infection

“…HEV infection exhibits distinct tropisms and different clinical characteristics in different populations. In particular, the elderly (>60 years old) are more susceptible to HEV 17 18 . Furthermore, the symptoms of HEV infection are more severe in pregnant women, in whom the mortality rate can be up to 28%, which is significantly higher than the average mortality rate in the rest of the population 19 20 21 .…”

Dengue viruses – an overview

“…Despite the lack of clinical symptoms, these models have been used extensively to study other aspects of DENV pathogenesis (212, 221–225). In addition, immunocompetent mouse models of DENV infection have been popular for drug and vaccine development studies since the intact immune system is valuable for assessing vaccine immunogenicity.…”

Non-Human Primate Models of Dengue Virus Infection: A Comparison of Viremia Levels and Antibody Responses during Primary and Secondary Infection among Old World and New World Monkeys

“…Mice that have been used as models of DENV infection include immunocompetent mice, human tissue engrafted-severe combined immunodeficiency (SCID) mice, interferon α, β, γ deficient AG129, RAG-hu, and the NOD/SCID/ IL-2Rγ/human CD34 transplant mice [2,31,32,39,44,58,59]. Although the mouse model is the primary model used in therapeutics and vaccine efficacy studies, limited replication of DENV have compromised the outcome of these studies [14][15][16]. Initial studies adopted intracranial inoculation and this method induced neurological diseases and paralysis, clinical signs which are atypical signs of dengue fever and classical signs of dengue hemorrhagic fever [23,60,61].…”

“…Thus, an animal model that faithfully mirrors the immune response pattern of those of human DENV infection is able to sustain viral replication and exhibits age-related clinical signs would be the ideal model for vaccine trials because candidate vaccines are evaluated by defining the viremia kinetics and the antibody responses [12,13]. Mice have been used in vaccine trials, but low levels of DENV replication potential have led to inconclusive outcomes regarding the potency and immune response [14][15][16]. Non-human primates (NHPs) are preferred because of the high similarities in genetic and immune responses to those of humans.…”