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Steroid hormone synthesis by vaccinia virus suppresses the inflammatory response to infection.

Reading PC, Moore JB, Smith GL - J. Exp. Med. (2003)

Bottom Line: Loss of A44L was associated with an attenuated phenotype.Subsequently, vDeltaA44L-infected animals had reduced weight loss and signs of illness, and displayed a vigorous pulmonary inflammatory response.This was characterized by rapid recruitment of CD4+ and CD8+ lymphocytes, enhanced IFN-gamma production and augmented cytotoxic T lymphocyte activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, Faculty of Medicine, Imperial College London, St. Mary's Campus, Norfolk Place, London W2 1PG, UK.

ABSTRACT
The 3beta-hydroxysteroid dehydrogenase (3beta-HSD) isoenzymes play a key role in cellular steroid hormone synthesis. Vaccinia virus (VV) also synthesizes steroid hormones with a 3beta-HSD enzyme (v3beta-HSD) encoded by gene A44L. Here we examined the effects of v3beta-HSD in VV disease using wild-type (vA44L), deletion (vDeltaA44L), and revertant (vA44L-rev) viruses in a murine intranasal model. Loss of A44L was associated with an attenuated phenotype. Early (days 1-3) after infection with vDeltaA44L or control viruses the only difference observed between groups was the reduced corticosterone level in lungs and plasma of vDeltaA44L-infected animals. Other parameters examined (body weight, signs of illness, temperature, virus titres, the pulmonary inflammatory infiltrate, and interferon [IFN]-gamma levels) were indistinguishable between groups. Subsequently, vDeltaA44L-infected animals had reduced weight loss and signs of illness, and displayed a vigorous pulmonary inflammatory response. This was characterized by rapid recruitment of CD4+ and CD8+ lymphocytes, enhanced IFN-gamma production and augmented cytotoxic T lymphocyte activity. These data suggest that steroid production by v3beta-HSD contributes to virus virulence by inhibiting an effective inflammatory response to infection.

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Corticosterone levels in plasma and lungs after intranasal infection with VV. Corticosterone levels were measured in (A) plasma and (B) lung extracts collected from BALB/c mice under low stress conditions (samples were obtained within 4 min of handling) at the indicated times after intranasal infection with 105 PFU of vA44L, vΔA44L, or A44L-rev. Lung extracts were prepared as described in Materials and Methods. Data represent mean ± SEM of four or five mice per time point and are expressed as ng/ml of plasma or as ng/g of lung tissue. Columns marked with an asterisk represent corticosterone levels from vΔA44L-infected mice that were significantly different to those from vA44L- and vA44L-rev-infected mice. *, P < 0.05, **, P < 0.02. (C) Titers of infectious virus in the lungs of mice after infection with 105 PFU of VV. Virus titers were determined by plaque assay on BS-C-1 cells and are expressed as PFU/g of lung tissue.
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fig7: Corticosterone levels in plasma and lungs after intranasal infection with VV. Corticosterone levels were measured in (A) plasma and (B) lung extracts collected from BALB/c mice under low stress conditions (samples were obtained within 4 min of handling) at the indicated times after intranasal infection with 105 PFU of vA44L, vΔA44L, or A44L-rev. Lung extracts were prepared as described in Materials and Methods. Data represent mean ± SEM of four or five mice per time point and are expressed as ng/ml of plasma or as ng/g of lung tissue. Columns marked with an asterisk represent corticosterone levels from vΔA44L-infected mice that were significantly different to those from vA44L- and vA44L-rev-infected mice. *, P < 0.05, **, P < 0.02. (C) Titers of infectious virus in the lungs of mice after infection with 105 PFU of VV. Virus titers were determined by plaque assay on BS-C-1 cells and are expressed as PFU/g of lung tissue.

Mentions: Data presented so far have demonstrated that the vΔA44L mutant is markedly attenuated in the murine intranasal model, and that after an initial period of 3–4 d when infection with each virus was indistinguishable, the attenuated phenotype of the vΔA44L mutant was accompanied by a more vigorous cellular inflammatory response in the lungs of infected mice. As the A44L encodes an active 3β-HSD and GCs and other steroids possess important immunomodulatory functions, the levels of corticosterone were determined in the plasma and lungs of VV-infected mice (Fig. 7, A and B) . Corticosterone is released after stress and as part of the acute phase response to infection, therefore we determined levels only at times when all indicators of disease (and therefore stress) were similar between groups. At days 1, 2, and 4 virus titers were similar in the lungs of vA44L-, vΔA44L-, or vA44L-rev–infected mice (Fig. 7 C), and no differences were observed in visible signs of illness, weight loss, body temperature, or the number of inflammatory cells and IFN-γ levels recovered from the BAL of infected mice (unpublished data). Corticosterone levels were, however, significantly lower in plasma at days 1 and 2 (Fig. 7 A) and in lung extracts at days 2 and 4 (Fig. 7 B) from vΔA44L-infected mice. After day 4 any differences in corticosterone levels between the groups would be difficult to interpret because the attenuated phenotype of vΔA44L is apparent and therefore stress levels might vary between groups. The enhanced levels of endogenous GCs observed in vA44L and vA44L-rev–infected mice suggest that A44L may have a direct effect upon local and systemic steroid levels during VV infection.


Steroid hormone synthesis by vaccinia virus suppresses the inflammatory response to infection.

Reading PC, Moore JB, Smith GL - J. Exp. Med. (2003)

Corticosterone levels in plasma and lungs after intranasal infection with VV. Corticosterone levels were measured in (A) plasma and (B) lung extracts collected from BALB/c mice under low stress conditions (samples were obtained within 4 min of handling) at the indicated times after intranasal infection with 105 PFU of vA44L, vΔA44L, or A44L-rev. Lung extracts were prepared as described in Materials and Methods. Data represent mean ± SEM of four or five mice per time point and are expressed as ng/ml of plasma or as ng/g of lung tissue. Columns marked with an asterisk represent corticosterone levels from vΔA44L-infected mice that were significantly different to those from vA44L- and vA44L-rev-infected mice. *, P < 0.05, **, P < 0.02. (C) Titers of infectious virus in the lungs of mice after infection with 105 PFU of VV. Virus titers were determined by plaque assay on BS-C-1 cells and are expressed as PFU/g of lung tissue.
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Related In: Results  -  Collection

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fig7: Corticosterone levels in plasma and lungs after intranasal infection with VV. Corticosterone levels were measured in (A) plasma and (B) lung extracts collected from BALB/c mice under low stress conditions (samples were obtained within 4 min of handling) at the indicated times after intranasal infection with 105 PFU of vA44L, vΔA44L, or A44L-rev. Lung extracts were prepared as described in Materials and Methods. Data represent mean ± SEM of four or five mice per time point and are expressed as ng/ml of plasma or as ng/g of lung tissue. Columns marked with an asterisk represent corticosterone levels from vΔA44L-infected mice that were significantly different to those from vA44L- and vA44L-rev-infected mice. *, P < 0.05, **, P < 0.02. (C) Titers of infectious virus in the lungs of mice after infection with 105 PFU of VV. Virus titers were determined by plaque assay on BS-C-1 cells and are expressed as PFU/g of lung tissue.
Mentions: Data presented so far have demonstrated that the vΔA44L mutant is markedly attenuated in the murine intranasal model, and that after an initial period of 3–4 d when infection with each virus was indistinguishable, the attenuated phenotype of the vΔA44L mutant was accompanied by a more vigorous cellular inflammatory response in the lungs of infected mice. As the A44L encodes an active 3β-HSD and GCs and other steroids possess important immunomodulatory functions, the levels of corticosterone were determined in the plasma and lungs of VV-infected mice (Fig. 7, A and B) . Corticosterone is released after stress and as part of the acute phase response to infection, therefore we determined levels only at times when all indicators of disease (and therefore stress) were similar between groups. At days 1, 2, and 4 virus titers were similar in the lungs of vA44L-, vΔA44L-, or vA44L-rev–infected mice (Fig. 7 C), and no differences were observed in visible signs of illness, weight loss, body temperature, or the number of inflammatory cells and IFN-γ levels recovered from the BAL of infected mice (unpublished data). Corticosterone levels were, however, significantly lower in plasma at days 1 and 2 (Fig. 7 A) and in lung extracts at days 2 and 4 (Fig. 7 B) from vΔA44L-infected mice. After day 4 any differences in corticosterone levels between the groups would be difficult to interpret because the attenuated phenotype of vΔA44L is apparent and therefore stress levels might vary between groups. The enhanced levels of endogenous GCs observed in vA44L and vA44L-rev–infected mice suggest that A44L may have a direct effect upon local and systemic steroid levels during VV infection.

Bottom Line: Loss of A44L was associated with an attenuated phenotype.Subsequently, vDeltaA44L-infected animals had reduced weight loss and signs of illness, and displayed a vigorous pulmonary inflammatory response.This was characterized by rapid recruitment of CD4+ and CD8+ lymphocytes, enhanced IFN-gamma production and augmented cytotoxic T lymphocyte activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Virology, Faculty of Medicine, Imperial College London, St. Mary's Campus, Norfolk Place, London W2 1PG, UK.

ABSTRACT
The 3beta-hydroxysteroid dehydrogenase (3beta-HSD) isoenzymes play a key role in cellular steroid hormone synthesis. Vaccinia virus (VV) also synthesizes steroid hormones with a 3beta-HSD enzyme (v3beta-HSD) encoded by gene A44L. Here we examined the effects of v3beta-HSD in VV disease using wild-type (vA44L), deletion (vDeltaA44L), and revertant (vA44L-rev) viruses in a murine intranasal model. Loss of A44L was associated with an attenuated phenotype. Early (days 1-3) after infection with vDeltaA44L or control viruses the only difference observed between groups was the reduced corticosterone level in lungs and plasma of vDeltaA44L-infected animals. Other parameters examined (body weight, signs of illness, temperature, virus titres, the pulmonary inflammatory infiltrate, and interferon [IFN]-gamma levels) were indistinguishable between groups. Subsequently, vDeltaA44L-infected animals had reduced weight loss and signs of illness, and displayed a vigorous pulmonary inflammatory response. This was characterized by rapid recruitment of CD4+ and CD8+ lymphocytes, enhanced IFN-gamma production and augmented cytotoxic T lymphocyte activity. These data suggest that steroid production by v3beta-HSD contributes to virus virulence by inhibiting an effective inflammatory response to infection.

Show MeSH
Related in: MedlinePlus