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Pan-HSV-2 IgG antibody in vaccinated mice and guinea pigs correlates with protection against herpes simplex virus 2.

Halford WP, Geltz J, Gershburg E - PLoS ONE (2013)

Bottom Line: These six HSV-2 immunogens elicited a wide range of pan-HSV-2 IgG levels spanning an ∼500-fold range.For 5 of the 6 immunogens tested, pre-challenge levels of pan-HSV-2 IgG quantitatively correlated with reductions in HSV-2 challenge virus shedding and increased survival frequency following HSV-2 challenge.Collectively, the results suggest that pan-HSV-2 IgG levels may provide a simple and useful screening tool for evaluating the potential of a HSV-2 vaccine candidate to elicit protection against HSV-2 genital herpes.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America. halford@siumed.edu

ABSTRACT
We lack a correlate of immunity to herpes simplex virus 2 (HSV-2) that may be used to differentiate whether a HSV-2 vaccine elicits robust or anemic protection against genital herpes. This gap in knowledge is often attributed to a failure to measure the correct component of the adaptive immune response to HSV-2. However, efforts to identify a correlate of immunity have focused on subunit vaccines that contain less than 3% of HSV-2's 40,000-amino-acid proteome. We were interested to determine if a correlate of immunity might be more readily identified if 1. animals were immunized with a polyvalent immunogen such as a live virus and/or 2. the magnitude of the vaccine-induced immune response was gauged in terms of the IgG antibody response to all of HSV-2's antigens (pan-HSV-2 IgG). Pre-challenge pan-HSV-2 IgG levels and protection against HSV-2 were compared in mice and/or guinea pigs immunized with a gD-2 subunit vaccine, wild-type HSV-2, or one of several attenuated HSV-2 ICP0 (-) viruses (0Δ254, 0Δ810, 0ΔRING, or 0ΔNLS). These six HSV-2 immunogens elicited a wide range of pan-HSV-2 IgG levels spanning an ∼500-fold range. For 5 of the 6 immunogens tested, pre-challenge levels of pan-HSV-2 IgG quantitatively correlated with reductions in HSV-2 challenge virus shedding and increased survival frequency following HSV-2 challenge. Collectively, the results suggest that pan-HSV-2 IgG levels may provide a simple and useful screening tool for evaluating the potential of a HSV-2 vaccine candidate to elicit protection against HSV-2 genital herpes.

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Pan-HSV-2 IgG levels correlate with protection against vaginal HSV-2 challenge in mice.(A) Design of mouse vaccine-challenge experiment. Mice were immunized in their right, rear footpads on Day 0 with gD-2, GFP, culture medium (mock), HSV-2 0ΔNLS, or HSV-2 MS, as described in the Results (n = 10 per group). Mice immunized with HSV-2 MS received 1 mg/ml acyclovir in drinking water from Days 0 to 20 post-immunization to restrain the pathogenesis of a primary exposure to wild-type HSV-2. All mice were boosted in their left, rear footpads on Day 30 with an equivalent, booster immunization with the exception that MS-immunized mice did not require acyclovir during the boost. On Day 60, blood was harvested, and on Days 90 or 100, mice were challenged with 500,000 pfu per vagina of wild-type HSV-2 MS. Seven and 3 days prior to HSV-2 MS challenge, each mouse received a subcutaneous injection of 2 mg DepoProvera® (medoxyprogesterone) to render mouse vaginas susceptible to HSV-2 challenge. (B) Mean ± sem pan-HSV-2 IgG levels in pre-challenge serum, as determined by a flow cytometry-based assay. The frequency with which mice survived until Day 30 post-challenge is indicated. (C) For each mouse (one symbol per animal), the average amount of infectious HSV-2 shed on Days 1, 3, 5, and 7 post-vaginal challenge (y-axis) was plotted as a function of pre-challenge pan-HSV-2 IgG levels observed in the same mouse (x-axis). The solid black line represents the best-fit linear regression model, y = 3.85–0.76x, for the 50 matched datum pairs. (D) Mean ± sem of log (pan-HSV-2 IgG) in each immunization group is plotted on the x-axis versus mean ± sem vaginal HSV-2 shedding on the y-axis. The solid black line represents the best-fit linear regression model, y = 3.89–0.79x, for these 5 matched averages (r2 = 0.98). Groups of immunized mice that exhibited a significant reduction in vaginal HSV-2 shedding relative to naïve mice are indicated by a single asterisk (*; p<0.05) or double-asterisk (**; p<0.001), as determined by one-way ANOVA and Tukey's post-hoc t-test.
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pone-0065523-g003: Pan-HSV-2 IgG levels correlate with protection against vaginal HSV-2 challenge in mice.(A) Design of mouse vaccine-challenge experiment. Mice were immunized in their right, rear footpads on Day 0 with gD-2, GFP, culture medium (mock), HSV-2 0ΔNLS, or HSV-2 MS, as described in the Results (n = 10 per group). Mice immunized with HSV-2 MS received 1 mg/ml acyclovir in drinking water from Days 0 to 20 post-immunization to restrain the pathogenesis of a primary exposure to wild-type HSV-2. All mice were boosted in their left, rear footpads on Day 30 with an equivalent, booster immunization with the exception that MS-immunized mice did not require acyclovir during the boost. On Day 60, blood was harvested, and on Days 90 or 100, mice were challenged with 500,000 pfu per vagina of wild-type HSV-2 MS. Seven and 3 days prior to HSV-2 MS challenge, each mouse received a subcutaneous injection of 2 mg DepoProvera® (medoxyprogesterone) to render mouse vaginas susceptible to HSV-2 challenge. (B) Mean ± sem pan-HSV-2 IgG levels in pre-challenge serum, as determined by a flow cytometry-based assay. The frequency with which mice survived until Day 30 post-challenge is indicated. (C) For each mouse (one symbol per animal), the average amount of infectious HSV-2 shed on Days 1, 3, 5, and 7 post-vaginal challenge (y-axis) was plotted as a function of pre-challenge pan-HSV-2 IgG levels observed in the same mouse (x-axis). The solid black line represents the best-fit linear regression model, y = 3.85–0.76x, for the 50 matched datum pairs. (D) Mean ± sem of log (pan-HSV-2 IgG) in each immunization group is plotted on the x-axis versus mean ± sem vaginal HSV-2 shedding on the y-axis. The solid black line represents the best-fit linear regression model, y = 3.89–0.79x, for these 5 matched averages (r2 = 0.98). Groups of immunized mice that exhibited a significant reduction in vaginal HSV-2 shedding relative to naïve mice are indicated by a single asterisk (*; p<0.05) or double-asterisk (**; p<0.001), as determined by one-way ANOVA and Tukey's post-hoc t-test.

Mentions: The design of the original experiment is reviewed. Mice were immunized on Days 0 and 30 in their right and left rear footpads, respectively, with 1. culture medium (naïve controls); 2. 2.5 µg green fluorescent protein (GFP) adjuvanted with alum and 10 µg MPL; 3. 2.5 µg gD-2306t[54] adjuvanted with alum and 10 µg MPL; 4. 106 pfu HSV-2 0ΔNLS, or 5. 106 pfu wild-type HSV-2 MS where acyclovir was used to limit the pathogenesis of the primary exposure to MS (Fig. 3A; n = 10 per group). Blood was drawn on Day 60 and mice were challenged on Days 90 or 100 with 500,000 pfu per vagina of HSV-2 MS. All n = 50 mice were swabbed between Days 1 and 7 post-challenge to measure vaginal HSV-2 shedding and disease onset was observed over a 30 day-period (Fig. 3A).


Pan-HSV-2 IgG antibody in vaccinated mice and guinea pigs correlates with protection against herpes simplex virus 2.

Halford WP, Geltz J, Gershburg E - PLoS ONE (2013)

Pan-HSV-2 IgG levels correlate with protection against vaginal HSV-2 challenge in mice.(A) Design of mouse vaccine-challenge experiment. Mice were immunized in their right, rear footpads on Day 0 with gD-2, GFP, culture medium (mock), HSV-2 0ΔNLS, or HSV-2 MS, as described in the Results (n = 10 per group). Mice immunized with HSV-2 MS received 1 mg/ml acyclovir in drinking water from Days 0 to 20 post-immunization to restrain the pathogenesis of a primary exposure to wild-type HSV-2. All mice were boosted in their left, rear footpads on Day 30 with an equivalent, booster immunization with the exception that MS-immunized mice did not require acyclovir during the boost. On Day 60, blood was harvested, and on Days 90 or 100, mice were challenged with 500,000 pfu per vagina of wild-type HSV-2 MS. Seven and 3 days prior to HSV-2 MS challenge, each mouse received a subcutaneous injection of 2 mg DepoProvera® (medoxyprogesterone) to render mouse vaginas susceptible to HSV-2 challenge. (B) Mean ± sem pan-HSV-2 IgG levels in pre-challenge serum, as determined by a flow cytometry-based assay. The frequency with which mice survived until Day 30 post-challenge is indicated. (C) For each mouse (one symbol per animal), the average amount of infectious HSV-2 shed on Days 1, 3, 5, and 7 post-vaginal challenge (y-axis) was plotted as a function of pre-challenge pan-HSV-2 IgG levels observed in the same mouse (x-axis). The solid black line represents the best-fit linear regression model, y = 3.85–0.76x, for the 50 matched datum pairs. (D) Mean ± sem of log (pan-HSV-2 IgG) in each immunization group is plotted on the x-axis versus mean ± sem vaginal HSV-2 shedding on the y-axis. The solid black line represents the best-fit linear regression model, y = 3.89–0.79x, for these 5 matched averages (r2 = 0.98). Groups of immunized mice that exhibited a significant reduction in vaginal HSV-2 shedding relative to naïve mice are indicated by a single asterisk (*; p<0.05) or double-asterisk (**; p<0.001), as determined by one-way ANOVA and Tukey's post-hoc t-test.
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Related In: Results  -  Collection

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pone-0065523-g003: Pan-HSV-2 IgG levels correlate with protection against vaginal HSV-2 challenge in mice.(A) Design of mouse vaccine-challenge experiment. Mice were immunized in their right, rear footpads on Day 0 with gD-2, GFP, culture medium (mock), HSV-2 0ΔNLS, or HSV-2 MS, as described in the Results (n = 10 per group). Mice immunized with HSV-2 MS received 1 mg/ml acyclovir in drinking water from Days 0 to 20 post-immunization to restrain the pathogenesis of a primary exposure to wild-type HSV-2. All mice were boosted in their left, rear footpads on Day 30 with an equivalent, booster immunization with the exception that MS-immunized mice did not require acyclovir during the boost. On Day 60, blood was harvested, and on Days 90 or 100, mice were challenged with 500,000 pfu per vagina of wild-type HSV-2 MS. Seven and 3 days prior to HSV-2 MS challenge, each mouse received a subcutaneous injection of 2 mg DepoProvera® (medoxyprogesterone) to render mouse vaginas susceptible to HSV-2 challenge. (B) Mean ± sem pan-HSV-2 IgG levels in pre-challenge serum, as determined by a flow cytometry-based assay. The frequency with which mice survived until Day 30 post-challenge is indicated. (C) For each mouse (one symbol per animal), the average amount of infectious HSV-2 shed on Days 1, 3, 5, and 7 post-vaginal challenge (y-axis) was plotted as a function of pre-challenge pan-HSV-2 IgG levels observed in the same mouse (x-axis). The solid black line represents the best-fit linear regression model, y = 3.85–0.76x, for the 50 matched datum pairs. (D) Mean ± sem of log (pan-HSV-2 IgG) in each immunization group is plotted on the x-axis versus mean ± sem vaginal HSV-2 shedding on the y-axis. The solid black line represents the best-fit linear regression model, y = 3.89–0.79x, for these 5 matched averages (r2 = 0.98). Groups of immunized mice that exhibited a significant reduction in vaginal HSV-2 shedding relative to naïve mice are indicated by a single asterisk (*; p<0.05) or double-asterisk (**; p<0.001), as determined by one-way ANOVA and Tukey's post-hoc t-test.
Mentions: The design of the original experiment is reviewed. Mice were immunized on Days 0 and 30 in their right and left rear footpads, respectively, with 1. culture medium (naïve controls); 2. 2.5 µg green fluorescent protein (GFP) adjuvanted with alum and 10 µg MPL; 3. 2.5 µg gD-2306t[54] adjuvanted with alum and 10 µg MPL; 4. 106 pfu HSV-2 0ΔNLS, or 5. 106 pfu wild-type HSV-2 MS where acyclovir was used to limit the pathogenesis of the primary exposure to MS (Fig. 3A; n = 10 per group). Blood was drawn on Day 60 and mice were challenged on Days 90 or 100 with 500,000 pfu per vagina of HSV-2 MS. All n = 50 mice were swabbed between Days 1 and 7 post-challenge to measure vaginal HSV-2 shedding and disease onset was observed over a 30 day-period (Fig. 3A).

Bottom Line: These six HSV-2 immunogens elicited a wide range of pan-HSV-2 IgG levels spanning an ∼500-fold range.For 5 of the 6 immunogens tested, pre-challenge levels of pan-HSV-2 IgG quantitatively correlated with reductions in HSV-2 challenge virus shedding and increased survival frequency following HSV-2 challenge.Collectively, the results suggest that pan-HSV-2 IgG levels may provide a simple and useful screening tool for evaluating the potential of a HSV-2 vaccine candidate to elicit protection against HSV-2 genital herpes.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America. halford@siumed.edu

ABSTRACT
We lack a correlate of immunity to herpes simplex virus 2 (HSV-2) that may be used to differentiate whether a HSV-2 vaccine elicits robust or anemic protection against genital herpes. This gap in knowledge is often attributed to a failure to measure the correct component of the adaptive immune response to HSV-2. However, efforts to identify a correlate of immunity have focused on subunit vaccines that contain less than 3% of HSV-2's 40,000-amino-acid proteome. We were interested to determine if a correlate of immunity might be more readily identified if 1. animals were immunized with a polyvalent immunogen such as a live virus and/or 2. the magnitude of the vaccine-induced immune response was gauged in terms of the IgG antibody response to all of HSV-2's antigens (pan-HSV-2 IgG). Pre-challenge pan-HSV-2 IgG levels and protection against HSV-2 were compared in mice and/or guinea pigs immunized with a gD-2 subunit vaccine, wild-type HSV-2, or one of several attenuated HSV-2 ICP0 (-) viruses (0Δ254, 0Δ810, 0ΔRING, or 0ΔNLS). These six HSV-2 immunogens elicited a wide range of pan-HSV-2 IgG levels spanning an ∼500-fold range. For 5 of the 6 immunogens tested, pre-challenge levels of pan-HSV-2 IgG quantitatively correlated with reductions in HSV-2 challenge virus shedding and increased survival frequency following HSV-2 challenge. Collectively, the results suggest that pan-HSV-2 IgG levels may provide a simple and useful screening tool for evaluating the potential of a HSV-2 vaccine candidate to elicit protection against HSV-2 genital herpes.

Show MeSH
Related in: MedlinePlus