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Role of humoral versus cellular responses induced by a protective dengue vaccine candidate.

Zellweger RM, Miller R, Eddy WE, White LJ, Johnston RE, Shresta S - PLoS Pathog. (2013)

Bottom Line: Severe dengue disease is associated with sub-protective levels of antibody, which exacerbate disease upon re-infection.A dengue vaccine should generate protective immunity without increasing severity of disease.This study explores the immunological basis of protection induced by a dengue vaccine and suggests that a safe and efficient vaccine against dengue should trigger both arms of the immune system.

View Article: PubMed Central - PubMed

Affiliation: La Jolla Institute for Allergy & Immunology, La Jolla, California, United States of America.

ABSTRACT
With 2.5 billion people at risk, dengue is a major emerging disease threat and an escalating public health problem worldwide. Dengue virus causes disease ranging from a self-limiting febrile illness (dengue fever) to the potentially fatal dengue hemorrhagic fever/dengue shock syndrome. Severe dengue disease is associated with sub-protective levels of antibody, which exacerbate disease upon re-infection. A dengue vaccine should generate protective immunity without increasing severity of disease. To date, the determinants of vaccine-mediated protection against dengue remain unclear, and additional correlates of protection are urgently needed. Here, mice were immunized with viral replicon particles expressing the dengue envelope protein ectodomain to assess the relative contribution of humoral versus cellular immunity to protection. Vaccination with viral replicon particles provided robust protection against dengue challenge. Vaccine-induced humoral responses had the potential to either protect from or exacerbate dengue disease upon challenge, whereas cellular immune responses were beneficial. This study explores the immunological basis of protection induced by a dengue vaccine and suggests that a safe and efficient vaccine against dengue should trigger both arms of the immune system.

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DENV2 E85-VRP provides long-term protection; and the interval between the two immunizations modulates the degree to which the vaccine-induced protection relies on CD8+ T cells.(A) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 42 and 33 days before challenge with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population (black circles), and one group was left untreated before challenge (baseline). Viral RNA was quantified in the liver 3 days after challenge. (B) AG129 mice were immunized twice with 1×106 IU DENV2 E85-VRP i.p. either 28 or 9 days apart. 28 days after the second immunization, mice were challenged with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population. Viral RNA was quantified in the liver 4 days after challenge. (C) AG129 mice were immunized as in B (28 or 9 days apart). 33 days after the second immunization, mice were challenged with 5×108 GE DENV. Before challenge, half of the mice were depleted of their CD4+ T cell population. Viral RNA was quantified in the liver 3 days after challenge. (D, E, F) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 28 days apart (-61/-33) or 9 days apart (-42/-33), and on day 0, serum levels of DENV-specific IgG were measured by ELISA (D), neutralizing titers were determined by PRNT50 (E), and DENV-specific IgG1, IgG2a, IgG2b and IgG3 were measured by ELISA (F). Each symbol depicts one mouse, except for D where n = 4 for the groups receiving B cells and 2 for the groups receiving no B cells (base and ADE) and F where n = 5 for experimental groups, naïve serum was included as a negative control, P-values from two-tailed unpaired t-test with Welch's correction, confidence interval 95%, * P≤0.05, ** P≤0.01, *** P≤0.001. Dotted line and symbols in gray as described in figure 1.
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ppat-1003723-g006: DENV2 E85-VRP provides long-term protection; and the interval between the two immunizations modulates the degree to which the vaccine-induced protection relies on CD8+ T cells.(A) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 42 and 33 days before challenge with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population (black circles), and one group was left untreated before challenge (baseline). Viral RNA was quantified in the liver 3 days after challenge. (B) AG129 mice were immunized twice with 1×106 IU DENV2 E85-VRP i.p. either 28 or 9 days apart. 28 days after the second immunization, mice were challenged with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population. Viral RNA was quantified in the liver 4 days after challenge. (C) AG129 mice were immunized as in B (28 or 9 days apart). 33 days after the second immunization, mice were challenged with 5×108 GE DENV. Before challenge, half of the mice were depleted of their CD4+ T cell population. Viral RNA was quantified in the liver 3 days after challenge. (D, E, F) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 28 days apart (-61/-33) or 9 days apart (-42/-33), and on day 0, serum levels of DENV-specific IgG were measured by ELISA (D), neutralizing titers were determined by PRNT50 (E), and DENV-specific IgG1, IgG2a, IgG2b and IgG3 were measured by ELISA (F). Each symbol depicts one mouse, except for D where n = 4 for the groups receiving B cells and 2 for the groups receiving no B cells (base and ADE) and F where n = 5 for experimental groups, naïve serum was included as a negative control, P-values from two-tailed unpaired t-test with Welch's correction, confidence interval 95%, * P≤0.05, ** P≤0.01, *** P≤0.001. Dotted line and symbols in gray as described in figure 1.

Mentions: We have shown that DENV2 E85-VRP-immunization confers CD8+ T cell-mediated short-term protection against DENV challenge. To examine whether DENV2 E85-VRP-immunization can confer longer-term protection against DENV challenge, AG129 mice were immunized twice with 1×106 IU of DENV2 E85-VRP i.p. 9 days apart (as described in all experiments so far), and mice were challenged with DENV 33 days after the second immunization. Half of the immunized mice were depleted of CD8+ T cells before challenge. Three days after challenge, viral RNA levels in the liver were significantly lower in the immunized mice compared to the non-immunized baseline group, and CD8-depletion abrogated this decrease in viral load (figure 6A). Thus, DENV2 E85-VRP immunization can provide CD8+ T cell-dependent, long-term protection against DENV, as determined by reduction of liver viral RNA titer 3 days post challenge in AG129 mice.


Role of humoral versus cellular responses induced by a protective dengue vaccine candidate.

Zellweger RM, Miller R, Eddy WE, White LJ, Johnston RE, Shresta S - PLoS Pathog. (2013)

DENV2 E85-VRP provides long-term protection; and the interval between the two immunizations modulates the degree to which the vaccine-induced protection relies on CD8+ T cells.(A) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 42 and 33 days before challenge with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population (black circles), and one group was left untreated before challenge (baseline). Viral RNA was quantified in the liver 3 days after challenge. (B) AG129 mice were immunized twice with 1×106 IU DENV2 E85-VRP i.p. either 28 or 9 days apart. 28 days after the second immunization, mice were challenged with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population. Viral RNA was quantified in the liver 4 days after challenge. (C) AG129 mice were immunized as in B (28 or 9 days apart). 33 days after the second immunization, mice were challenged with 5×108 GE DENV. Before challenge, half of the mice were depleted of their CD4+ T cell population. Viral RNA was quantified in the liver 3 days after challenge. (D, E, F) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 28 days apart (-61/-33) or 9 days apart (-42/-33), and on day 0, serum levels of DENV-specific IgG were measured by ELISA (D), neutralizing titers were determined by PRNT50 (E), and DENV-specific IgG1, IgG2a, IgG2b and IgG3 were measured by ELISA (F). Each symbol depicts one mouse, except for D where n = 4 for the groups receiving B cells and 2 for the groups receiving no B cells (base and ADE) and F where n = 5 for experimental groups, naïve serum was included as a negative control, P-values from two-tailed unpaired t-test with Welch's correction, confidence interval 95%, * P≤0.05, ** P≤0.01, *** P≤0.001. Dotted line and symbols in gray as described in figure 1.
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ppat-1003723-g006: DENV2 E85-VRP provides long-term protection; and the interval between the two immunizations modulates the degree to which the vaccine-induced protection relies on CD8+ T cells.(A) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 42 and 33 days before challenge with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population (black circles), and one group was left untreated before challenge (baseline). Viral RNA was quantified in the liver 3 days after challenge. (B) AG129 mice were immunized twice with 1×106 IU DENV2 E85-VRP i.p. either 28 or 9 days apart. 28 days after the second immunization, mice were challenged with 5×108 GE DENV. Half of the mice were depleted of their CD8+ T cell population. Viral RNA was quantified in the liver 4 days after challenge. (C) AG129 mice were immunized as in B (28 or 9 days apart). 33 days after the second immunization, mice were challenged with 5×108 GE DENV. Before challenge, half of the mice were depleted of their CD4+ T cell population. Viral RNA was quantified in the liver 3 days after challenge. (D, E, F) AG129 mice were immunized with 1×106 IU DENV2 E85-VRP i.p. 28 days apart (-61/-33) or 9 days apart (-42/-33), and on day 0, serum levels of DENV-specific IgG were measured by ELISA (D), neutralizing titers were determined by PRNT50 (E), and DENV-specific IgG1, IgG2a, IgG2b and IgG3 were measured by ELISA (F). Each symbol depicts one mouse, except for D where n = 4 for the groups receiving B cells and 2 for the groups receiving no B cells (base and ADE) and F where n = 5 for experimental groups, naïve serum was included as a negative control, P-values from two-tailed unpaired t-test with Welch's correction, confidence interval 95%, * P≤0.05, ** P≤0.01, *** P≤0.001. Dotted line and symbols in gray as described in figure 1.
Mentions: We have shown that DENV2 E85-VRP-immunization confers CD8+ T cell-mediated short-term protection against DENV challenge. To examine whether DENV2 E85-VRP-immunization can confer longer-term protection against DENV challenge, AG129 mice were immunized twice with 1×106 IU of DENV2 E85-VRP i.p. 9 days apart (as described in all experiments so far), and mice were challenged with DENV 33 days after the second immunization. Half of the immunized mice were depleted of CD8+ T cells before challenge. Three days after challenge, viral RNA levels in the liver were significantly lower in the immunized mice compared to the non-immunized baseline group, and CD8-depletion abrogated this decrease in viral load (figure 6A). Thus, DENV2 E85-VRP immunization can provide CD8+ T cell-dependent, long-term protection against DENV, as determined by reduction of liver viral RNA titer 3 days post challenge in AG129 mice.

Bottom Line: Severe dengue disease is associated with sub-protective levels of antibody, which exacerbate disease upon re-infection.A dengue vaccine should generate protective immunity without increasing severity of disease.This study explores the immunological basis of protection induced by a dengue vaccine and suggests that a safe and efficient vaccine against dengue should trigger both arms of the immune system.

View Article: PubMed Central - PubMed

Affiliation: La Jolla Institute for Allergy & Immunology, La Jolla, California, United States of America.

ABSTRACT
With 2.5 billion people at risk, dengue is a major emerging disease threat and an escalating public health problem worldwide. Dengue virus causes disease ranging from a self-limiting febrile illness (dengue fever) to the potentially fatal dengue hemorrhagic fever/dengue shock syndrome. Severe dengue disease is associated with sub-protective levels of antibody, which exacerbate disease upon re-infection. A dengue vaccine should generate protective immunity without increasing severity of disease. To date, the determinants of vaccine-mediated protection against dengue remain unclear, and additional correlates of protection are urgently needed. Here, mice were immunized with viral replicon particles expressing the dengue envelope protein ectodomain to assess the relative contribution of humoral versus cellular immunity to protection. Vaccination with viral replicon particles provided robust protection against dengue challenge. Vaccine-induced humoral responses had the potential to either protect from or exacerbate dengue disease upon challenge, whereas cellular immune responses were beneficial. This study explores the immunological basis of protection induced by a dengue vaccine and suggests that a safe and efficient vaccine against dengue should trigger both arms of the immune system.

Show MeSH
Related in: MedlinePlus