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Differential replicative ability of clinical dengue virus isolates in an immunocompetent C57BL/6 mouse model.

Barros VE, dos Santos-Junior NN, Amarilla AA, Soares AM, Lourencini R, Trabuco AC, Aquino VH - BMC Microbiol. (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

Discussion: 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.

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Susceptibility of C57BL/6 mice to infection with DENV. The animals were infected with D3/BR/SL3/02 (n = 5) (a, b and c) and D2/BR/RP/RMB/2009 (n = 5) (a, d and e) isolates, and Mochizuki strain (n = 5) (a, f and g). The infection was confirmed by detection of the virus genome by real-time RT-PCR in serum (a) and different organs (b-g). The animals were infected with D3/BR/SL3/02 and D2/BR/RP/RMB/2009 (n = 5) isolates, and Mochizuki strain, which were incubated with PBS (b, d and f, respectively) or enhancing antibodies (c, e and g, respectively). Data represent the mean values ± SD. The results are representative of two similar and independent experiments. *p < 0.05 when viruses incubated with heterologous immune sera were compared to viruses incubated with PBS
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Fig5: Susceptibility of C57BL/6 mice to infection with DENV. The animals were infected with D3/BR/SL3/02 (n = 5) (a, b and c) and D2/BR/RP/RMB/2009 (n = 5) (a, d and e) isolates, and Mochizuki strain (n = 5) (a, f and g). The infection was confirmed by detection of the virus genome by real-time RT-PCR in serum (a) and different organs (b-g). The animals were infected with D3/BR/SL3/02 and D2/BR/RP/RMB/2009 (n = 5) isolates, and Mochizuki strain, which were incubated with PBS (b, d and f, respectively) or enhancing antibodies (c, e and g, respectively). Data represent the mean values ± SD. The results are representative of two similar and independent experiments. *p < 0.05 when viruses incubated with heterologous immune sera were compared to viruses incubated with PBS

Mentions: The D3/BR/SL3/02 and D2/BR/RP/RMB/2009 isolates, and the Mochizuki strain were incubated with enhancing antibodies or PBS as mentioned in the ADE assay, and then used to infect C57BL/6 mice via the i.p. route. The susceptibility of the C57BL/6 mice to infection with DENV was again confirmed by detection of virus genomes in the serum and several organs (Fig. 5). Animals infected with the D3/BR/SL3/02 isolate showed a longer period of viremia (up to 7 days p.i.) than the animals infected with the other viruses (Fig. 5a). In addition, enhancing antibodies induced a higher level of viremia (Fig. 5a) and the appearance of virus in the brain (Fig. 5c) of the D3/BR/SL3/08-infected animals. Mice infected with the Mochizuki strain showed viremia only on day 2 p.i., while mice infected with D2/BR/RP/RMB/2009 did not show viremia. The use of heterologous antibodies did not change greatly the profile of virus detection in bloods and organs of animals infected with D2/BR/RP/RMB/2009 isolate and Mochizuki strain.Fig. 5


Differential replicative ability of clinical dengue virus isolates in an immunocompetent C57BL/6 mouse model.

Barros VE, dos Santos-Junior NN, Amarilla AA, Soares AM, Lourencini R, Trabuco AC, Aquino VH - BMC Microbiol. (2015)

Susceptibility of C57BL/6 mice to infection with DENV. The animals were infected with D3/BR/SL3/02 (n = 5) (a, b and c) and D2/BR/RP/RMB/2009 (n = 5) (a, d and e) isolates, and Mochizuki strain (n = 5) (a, f and g). The infection was confirmed by detection of the virus genome by real-time RT-PCR in serum (a) and different organs (b-g). The animals were infected with D3/BR/SL3/02 and D2/BR/RP/RMB/2009 (n = 5) isolates, and Mochizuki strain, which were incubated with PBS (b, d and f, respectively) or enhancing antibodies (c, e and g, respectively). Data represent the mean values ± SD. The results are representative of two similar and independent experiments. *p < 0.05 when viruses incubated with heterologous immune sera were compared to viruses incubated with PBS
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4587874&req=5

Fig5: Susceptibility of C57BL/6 mice to infection with DENV. The animals were infected with D3/BR/SL3/02 (n = 5) (a, b and c) and D2/BR/RP/RMB/2009 (n = 5) (a, d and e) isolates, and Mochizuki strain (n = 5) (a, f and g). The infection was confirmed by detection of the virus genome by real-time RT-PCR in serum (a) and different organs (b-g). The animals were infected with D3/BR/SL3/02 and D2/BR/RP/RMB/2009 (n = 5) isolates, and Mochizuki strain, which were incubated with PBS (b, d and f, respectively) or enhancing antibodies (c, e and g, respectively). Data represent the mean values ± SD. The results are representative of two similar and independent experiments. *p < 0.05 when viruses incubated with heterologous immune sera were compared to viruses incubated with PBS
Mentions: The D3/BR/SL3/02 and D2/BR/RP/RMB/2009 isolates, and the Mochizuki strain were incubated with enhancing antibodies or PBS as mentioned in the ADE assay, and then used to infect C57BL/6 mice via the i.p. route. The susceptibility of the C57BL/6 mice to infection with DENV was again confirmed by detection of virus genomes in the serum and several organs (Fig. 5). Animals infected with the D3/BR/SL3/02 isolate showed a longer period of viremia (up to 7 days p.i.) than the animals infected with the other viruses (Fig. 5a). In addition, enhancing antibodies induced a higher level of viremia (Fig. 5a) and the appearance of virus in the brain (Fig. 5c) of the D3/BR/SL3/08-infected animals. Mice infected with the Mochizuki strain showed viremia only on day 2 p.i., while mice infected with D2/BR/RP/RMB/2009 did not show viremia. The use of heterologous antibodies did not change greatly the profile of virus detection in bloods and organs of animals infected with D2/BR/RP/RMB/2009 isolate and Mochizuki strain.Fig. 5

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

Discussion: 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.

Show MeSH
Related in: MedlinePlus