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Basal Autophagy Is Required for Herpes simplex Virus-2 Infection.

Yakoub AM, Shukla D - Sci Rep (2015)

Bottom Line: Thus, we investigated the importance of basal autophagy for HSV-2 infection, using pharmacological autophagy suppression or cells genetically deficient in an autophagy-essential gene (ATG5).Interference with basal autophagy flux in cells significantly reduced viral replication and diminished the infection.These results indicate that basal autophagy plays an indispensable role required for a productive infection.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Microbiology and Immunology, University of Illinois, Chicago, IL USA, 60612 [2] Department of Ophthalmology and Visual Sciences, University of Illinois Medical Center, Chicago, IL USA, 60612.

ABSTRACT
Autophagy is a conserved catabolic process of the cell, which plays an important role in regulating plethora of infections. The role of autophagy in Herpes simplex virus-2 (HSV-2) infection is unknown. Here, we found that HSV-2 does not allow induction of an autophagic response to infection, but maintains basal autophagy levels mostly unchanged during productive infection. Thus, we investigated the importance of basal autophagy for HSV-2 infection, using pharmacological autophagy suppression or cells genetically deficient in an autophagy-essential gene (ATG5). Interference with basal autophagy flux in cells significantly reduced viral replication and diminished the infection. These results indicate that basal autophagy plays an indispensable role required for a productive infection. Importantly, this study draws a sharp distinction between induced and basal autophagy, where the former acts as a viral clearance mechanism abrogating infection, while the latter supports infection.

No MeSH data available.


Related in: MedlinePlus

Monitoring autophagy flux during HSV-2 infection.(a and c). Human foreskin fibroblasts were uninfected or infected with different MOIs of HSV-2 for 1 hr (panel a) or 6 hrs (panels c). The cells were then harvested and lysed, and the lysate was immunoblotted for p62 to assess autophagy flux. (b) Quantification of the relative p62 levels in (a), after normalization to GAPDH. (d) Quantification of the relative p62 levels in (c), after normalization to GAPDH.
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f1: Monitoring autophagy flux during HSV-2 infection.(a and c). Human foreskin fibroblasts were uninfected or infected with different MOIs of HSV-2 for 1 hr (panel a) or 6 hrs (panels c). The cells were then harvested and lysed, and the lysate was immunoblotted for p62 to assess autophagy flux. (b) Quantification of the relative p62 levels in (a), after normalization to GAPDH. (d) Quantification of the relative p62 levels in (c), after normalization to GAPDH.

Mentions: In response to HSV-1 infection, we previously found that autophagy levels may be slightly inhibited, or in most cases remain unchanged, during productive HSV-1 infection29. The autophagic response to HSV-2 infection was not previously assessed. Thus we monitored autophagy flux in cells during HSV-2 infection using sequestosome1 (or p62) immunoblotting. p62 is a protein that is degraded mainly by autophagy and thus its levels represent a reliable indicator of autophagy flux in cells303132. Id est, accumulation of p62 marks suppression of the autophagy flux, whereas its depletion reflects autophagy induction303132. We found that HSV-2 infection does not cause any significant changes in autophagy flux in host cells (Fig. 1a–d). This result indicated that HSV-2, similarly to HSV-1, prevents autophagy induction in response to infection, but meanwhile maintains the basal autophagy activity of the host mostly unhampered.


Basal Autophagy Is Required for Herpes simplex Virus-2 Infection.

Yakoub AM, Shukla D - Sci Rep (2015)

Monitoring autophagy flux during HSV-2 infection.(a and c). Human foreskin fibroblasts were uninfected or infected with different MOIs of HSV-2 for 1 hr (panel a) or 6 hrs (panels c). The cells were then harvested and lysed, and the lysate was immunoblotted for p62 to assess autophagy flux. (b) Quantification of the relative p62 levels in (a), after normalization to GAPDH. (d) Quantification of the relative p62 levels in (c), after normalization to GAPDH.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4528227&req=5

f1: Monitoring autophagy flux during HSV-2 infection.(a and c). Human foreskin fibroblasts were uninfected or infected with different MOIs of HSV-2 for 1 hr (panel a) or 6 hrs (panels c). The cells were then harvested and lysed, and the lysate was immunoblotted for p62 to assess autophagy flux. (b) Quantification of the relative p62 levels in (a), after normalization to GAPDH. (d) Quantification of the relative p62 levels in (c), after normalization to GAPDH.
Mentions: In response to HSV-1 infection, we previously found that autophagy levels may be slightly inhibited, or in most cases remain unchanged, during productive HSV-1 infection29. The autophagic response to HSV-2 infection was not previously assessed. Thus we monitored autophagy flux in cells during HSV-2 infection using sequestosome1 (or p62) immunoblotting. p62 is a protein that is degraded mainly by autophagy and thus its levels represent a reliable indicator of autophagy flux in cells303132. Id est, accumulation of p62 marks suppression of the autophagy flux, whereas its depletion reflects autophagy induction303132. We found that HSV-2 infection does not cause any significant changes in autophagy flux in host cells (Fig. 1a–d). This result indicated that HSV-2, similarly to HSV-1, prevents autophagy induction in response to infection, but meanwhile maintains the basal autophagy activity of the host mostly unhampered.

Bottom Line: Thus, we investigated the importance of basal autophagy for HSV-2 infection, using pharmacological autophagy suppression or cells genetically deficient in an autophagy-essential gene (ATG5).Interference with basal autophagy flux in cells significantly reduced viral replication and diminished the infection.These results indicate that basal autophagy plays an indispensable role required for a productive infection.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Microbiology and Immunology, University of Illinois, Chicago, IL USA, 60612 [2] Department of Ophthalmology and Visual Sciences, University of Illinois Medical Center, Chicago, IL USA, 60612.

ABSTRACT
Autophagy is a conserved catabolic process of the cell, which plays an important role in regulating plethora of infections. The role of autophagy in Herpes simplex virus-2 (HSV-2) infection is unknown. Here, we found that HSV-2 does not allow induction of an autophagic response to infection, but maintains basal autophagy levels mostly unchanged during productive infection. Thus, we investigated the importance of basal autophagy for HSV-2 infection, using pharmacological autophagy suppression or cells genetically deficient in an autophagy-essential gene (ATG5). Interference with basal autophagy flux in cells significantly reduced viral replication and diminished the infection. These results indicate that basal autophagy plays an indispensable role required for a productive infection. Importantly, this study draws a sharp distinction between induced and basal autophagy, where the former acts as a viral clearance mechanism abrogating infection, while the latter supports infection.

No MeSH data available.


Related in: MedlinePlus