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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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Flow cytometry-based measurement of pan-HSV-2 IgG antibody levels.A and B. Immunofluorescent labeling of fixed HSV-2 plaques with a 1∶6,000 dilution of (A) naïve mouse serum or (B) HSV-2 antiserum obtained from mice immunized with HSV-2 0ΔNLS [53]. Mouse IgG binding was visualized with AlexaFluor594-labeled goat anti-mouse IgG (H+L). C and D. Two-color flow cytometric analysis of a fixed, single-cell suspension of CFSE-labeled, HSV-2-infected (HSV-2+) Vero cells mixed with uninfected (UI) Vero cells. Fixed cells were incubated with a 1∶6,000 dilution of (C) naïve mouse serum or (D) mouse HSV-2 antiserum and APC-labeled goat anti-mouse IgG, and were analyzed for CFSE (FL1) and APC (FL4) fluorescent intensity. E. Pan-HSV-2 IgG levels in the serum of n = 6 naïve mice versus n = 6 HSV-2 0ΔNLS-immunized mice, as determined by the ΔMFI between HSV-2+ and UI cells.
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pone-0065523-g001: Flow cytometry-based measurement of pan-HSV-2 IgG antibody levels.A and B. Immunofluorescent labeling of fixed HSV-2 plaques with a 1∶6,000 dilution of (A) naïve mouse serum or (B) HSV-2 antiserum obtained from mice immunized with HSV-2 0ΔNLS [53]. Mouse IgG binding was visualized with AlexaFluor594-labeled goat anti-mouse IgG (H+L). C and D. Two-color flow cytometric analysis of a fixed, single-cell suspension of CFSE-labeled, HSV-2-infected (HSV-2+) Vero cells mixed with uninfected (UI) Vero cells. Fixed cells were incubated with a 1∶6,000 dilution of (C) naïve mouse serum or (D) mouse HSV-2 antiserum and APC-labeled goat anti-mouse IgG, and were analyzed for CFSE (FL1) and APC (FL4) fluorescent intensity. E. Pan-HSV-2 IgG levels in the serum of n = 6 naïve mice versus n = 6 HSV-2 0ΔNLS-immunized mice, as determined by the ΔMFI between HSV-2+ and UI cells.

Mentions: The presence of serum IgG antibodies that bind total HSV-2 antigens (pan-HSV-2 IgG) may be qualitatively tested by immunofluorescent staining of HSV-2 plaques in fixed Vero cell monolayers (Fig. 1A, B). A more quantitative, flow-cytometry-based variant of this assay was developed. Single-cell suspensions of HSV-2-infected (HSV-2+) and uninfected (UI) Vero cells were obtained by dispersing culture monolayers, fixing and permeabilizing cells, and filtering through 40 µm mesh and a 25-g needle to remove cell clumps. To permit antibody staining of HSV-2+ versus UI cells in a single reaction, HSV-2+ cells were labeled with the green fluorophore carboxyfluorescein diacetate, succinimidyl ester (CFSE).


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)

Flow cytometry-based measurement of pan-HSV-2 IgG antibody levels.A and B. Immunofluorescent labeling of fixed HSV-2 plaques with a 1∶6,000 dilution of (A) naïve mouse serum or (B) HSV-2 antiserum obtained from mice immunized with HSV-2 0ΔNLS [53]. Mouse IgG binding was visualized with AlexaFluor594-labeled goat anti-mouse IgG (H+L). C and D. Two-color flow cytometric analysis of a fixed, single-cell suspension of CFSE-labeled, HSV-2-infected (HSV-2+) Vero cells mixed with uninfected (UI) Vero cells. Fixed cells were incubated with a 1∶6,000 dilution of (C) naïve mouse serum or (D) mouse HSV-2 antiserum and APC-labeled goat anti-mouse IgG, and were analyzed for CFSE (FL1) and APC (FL4) fluorescent intensity. E. Pan-HSV-2 IgG levels in the serum of n = 6 naïve mice versus n = 6 HSV-2 0ΔNLS-immunized mice, as determined by the ΔMFI between HSV-2+ and UI cells.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3675040&req=5

pone-0065523-g001: Flow cytometry-based measurement of pan-HSV-2 IgG antibody levels.A and B. Immunofluorescent labeling of fixed HSV-2 plaques with a 1∶6,000 dilution of (A) naïve mouse serum or (B) HSV-2 antiserum obtained from mice immunized with HSV-2 0ΔNLS [53]. Mouse IgG binding was visualized with AlexaFluor594-labeled goat anti-mouse IgG (H+L). C and D. Two-color flow cytometric analysis of a fixed, single-cell suspension of CFSE-labeled, HSV-2-infected (HSV-2+) Vero cells mixed with uninfected (UI) Vero cells. Fixed cells were incubated with a 1∶6,000 dilution of (C) naïve mouse serum or (D) mouse HSV-2 antiserum and APC-labeled goat anti-mouse IgG, and were analyzed for CFSE (FL1) and APC (FL4) fluorescent intensity. E. Pan-HSV-2 IgG levels in the serum of n = 6 naïve mice versus n = 6 HSV-2 0ΔNLS-immunized mice, as determined by the ΔMFI between HSV-2+ and UI cells.
Mentions: The presence of serum IgG antibodies that bind total HSV-2 antigens (pan-HSV-2 IgG) may be qualitatively tested by immunofluorescent staining of HSV-2 plaques in fixed Vero cell monolayers (Fig. 1A, B). A more quantitative, flow-cytometry-based variant of this assay was developed. Single-cell suspensions of HSV-2-infected (HSV-2+) and uninfected (UI) Vero cells were obtained by dispersing culture monolayers, fixing and permeabilizing cells, and filtering through 40 µm mesh and a 25-g needle to remove cell clumps. To permit antibody staining of HSV-2+ versus UI cells in a single reaction, HSV-2+ cells were labeled with the green fluorophore carboxyfluorescein diacetate, succinimidyl ester (CFSE).

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