title: Differential replicative ability of clinical dengue virus isolates in an immunocompetent C57BL/6 mouse model.
abstract: BACKGROUND
  Several experimental animal models have been used to study the pathogenesis of dengue disease; however, most of the studies used laboratory-adapted viruses, which lack the virulence of viruses circulating in humans. The aim of this study was to analyze the ability of clinical Dengue virus (DENV) isolates (D2/BR/RP/RMB/09 and D3/BR/SL3/02) to infect immunocompetent C57BL/6 mice.
  
  
  METHODS
  Two strategies of intraperitoneal infection, which were based on the concept of the antibody dependent enhancement phenomenon, were used. In one strategy, the animals were inoculated with macrophages infected in vitro with dengue viruses, which were incubated with enhancing antibodies, and in the other strategy, the animals were inoculated with a complex of enhancing antibodies and dengue viruses.
  
  
  RESULTS
  The D3/BR/SL3/08 isolate showed a higher ability of infection (virus RNA was more frequently detected in the serum and in several organs) in the experimental model compared to both the D2/BR/RP/RMB/2009 isolate and a laboratory adapted DENV-1 strain (Mochizuki strain), regardless of the infection strategy used. The main features of the D3/BR/SL3/08 isolate were its neuroinvasiveness and the induction of an extended period of viremia. Enhancing antibodies did not influence on the infection of animals when macrophages were used, but the level of viremia was increased when they were used as a complex with a D3/BR/SL3/02 isolate.
  
  
  CONCLUSIONS
  We showed that DENV isolates could infect immunocompetent C57BL/6 mice, which have has been previously used to study some aspect of dengue disease when infected with laboratory adapted strains. DENV genome was detected in the same organs found in humans when autopsy and biopsy samples were analyzed, showing that C57BL/6 mice reproduce some aspects of the DENV tropism observed in humans. The main difference observed between the D3/BR/SL3/02 and D2/BR/RP/RMB/2009 clinical isolates was the neuroinvasive ability of the first one. Neuroinvasiveness has been described in some DENV infected cases and is common for other members of the Flavivirus genus.
  
  
  CONCLUSIONS
  These results suggest that C57BL/6 mice can be used as an experimental model to evaluate virulence differences among DENV clinical isolates.
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. veridias@yahoo.com.br.
authors.forename: Veridiana Ester
authors.initials: VE
authors.lastname: Barros
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. nilton4000@yahoo.com.br.
authors.forename: Nilton Nascimento
authors.initials: NN
authors.lastname: dos Santos-Junior
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. alberilla@usp.br.
authors.forename: Alberto Anastacio
authors.initials: AA
authors.lastname: Amarilla
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. dri.msoares@gmail.com.
authors.forename: Adriana Moreira
authors.initials: AM
authors.lastname: Soares
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. rafafurlanis@hotmail.com.
authors.forename: Rafael
authors.initials: R
authors.lastname: Lourencini
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. mandy.ct@fcfrp.usp.br.
authors.forename: Amanda Cristina
authors.initials: AC
authors.lastname: Trabuco
authors.affiliation: Laboratory of Virology, Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirao Preto, University of Sao Paulo, Av do Café, s/n, CEP: 14040-903, Ribeirao Preto, Sao Paulo, Brazil. vhugo@fcfrp.usp.br.
authors.forename: Victor Hugo
authors.initials: VH
authors.lastname: Aquino
mesh_terms: D000825:Animal Structures / Q000821:virology; D000818:Animals; D019138:Antibodies, Blocking / Q000378:metabolism; D003715:Dengue / Q000821:virology*; D003716:Dengue Virus / Q000302:isolation & purification / Q000502:physiology*; D004195:Disease Models, Animal; D006801:Humans; D007274:Injections, Intraperitoneal; D008264:Macrophages / Q000821:virology; D008810:Mice, Inbred C57BL; D056189:Viral Tropism; D014779:Virus Replication
chemical_list: D019138:Antibodies, Blocking