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Griffithsin tandemers: flexible and potent lectin inhibitors of the human immunodeficiency virus.

Moulaei T, Alexandre KB, Shenoy SR, Meyerson JR, Krumpe LR, Constantine B, Wilson J, Buckheit RW, McMahon JB, Subramaniam S, Wlodawer A, O'Keefe BR - Retrovirology (2015)

Bottom Line: Previously, we have engineered and analyzed several monomeric forms of this lectin (mGRFT) with anti-HIV EC50 values ranging up to 323 nM.Based on our previous analysis of mGRFT, we hypothesized that the orientation and spacing of the carbohydrate binding domains GRFT were key to its antiviral activity.We also demonstrate by dynamic light scattering and cryo-electron microscopy that mGRFT tandemers do not aggregate HIV virions.

View Article: PubMed Central - PubMed

Affiliation: Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702-1201, USA. tinoush@umd.edu.

ABSTRACT

Background: The lectin griffithsin (GRFT) is a potent antiviral agent capable of prevention and treatment of infections caused by a number of enveloped viruses and is currently under development as an anti-HIV microbicide. In addition to its broad antiviral activity, GRFT is stable at high temperature and at a broad pH range, displays little toxicity and immunogenicity, and is amenable to large-scale manufacturing. Native GRFT is a domain-swapped homodimer that binds to viral envelope glycoproteins and has displayed mid-picomolar activity in cell-based anti-HIV assays. Previously, we have engineered and analyzed several monomeric forms of this lectin (mGRFT) with anti-HIV EC50 values ranging up to 323 nM. Based on our previous analysis of mGRFT, we hypothesized that the orientation and spacing of the carbohydrate binding domains GRFT were key to its antiviral activity.

Results: Here we present data on engineered tandem repeats of mGRFT (mGRFT tandemers) with antiviral activity at concentrations as low as one picomolar in whole-cell anti-HIV assays. mGRFT tandemers were analyzed thermodynamically, both individually and in complex with HIV-1 gp120. We also demonstrate by dynamic light scattering and cryo-electron microscopy that mGRFT tandemers do not aggregate HIV virions. This establishes that, although the intra-virion crosslinking of HIV envelope glycoproteins is likely integral to their activity, the antiviral activity of these lectins is not due to virus aggregation caused by inter-virion crosslinking.

Conclusions: The engineered tandemer constructs of mGRFT may provide novel and powerful agents for prevention of infection by HIV and other enveloped viruses.

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Related in: MedlinePlus

Results of dynamic light scattering experiments on HIV-1BALvirions treated with GRFT, mGRFT, or the mGRFT tandemers. Dynamic light scattering traces are shown for HIV-1BAL viruses without lectin, with mGRFT, with GRFT, or with one of the tandemers. Negative controls with buffers or purified lectin did not measurably scatter light.
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Fig4: Results of dynamic light scattering experiments on HIV-1BALvirions treated with GRFT, mGRFT, or the mGRFT tandemers. Dynamic light scattering traces are shown for HIV-1BAL viruses without lectin, with mGRFT, with GRFT, or with one of the tandemers. Negative controls with buffers or purified lectin did not measurably scatter light.

Mentions: One of the common attributes of many lectins is their capacity to agglutinate pathogens [32]. Although antiviral lectins such as GRFT have been shown not to agglutinate human cells [14], it has been suggested that these lectins, which contain multiple binding domains, aggregate viruses [30]. To determine if this was true and to evaluate the role that the enhanced flexibility in binding domains may play in this phenomenon, we used dynamic light scattering to measure the aggregation of HIV-1BAL virions after treatment with mGRFT, GRFT, or one of the four GRFT tandemers. As shown in FigureĀ 4, GRFT did aggregate HIV-1BAL virions to a significant extent when compared to untreated virions. As expected, mGRFT, with only a single binding domain, did not aggregate virions but, interestingly, also none of the GRFT tandemers, including 4mGRFT with its four binding domains, caused virions to aggregate.Figure 4


Griffithsin tandemers: flexible and potent lectin inhibitors of the human immunodeficiency virus.

Moulaei T, Alexandre KB, Shenoy SR, Meyerson JR, Krumpe LR, Constantine B, Wilson J, Buckheit RW, McMahon JB, Subramaniam S, Wlodawer A, O'Keefe BR - Retrovirology (2015)

Results of dynamic light scattering experiments on HIV-1BALvirions treated with GRFT, mGRFT, or the mGRFT tandemers. Dynamic light scattering traces are shown for HIV-1BAL viruses without lectin, with mGRFT, with GRFT, or with one of the tandemers. Negative controls with buffers or purified lectin did not measurably scatter light.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4419512&req=5

Fig4: Results of dynamic light scattering experiments on HIV-1BALvirions treated with GRFT, mGRFT, or the mGRFT tandemers. Dynamic light scattering traces are shown for HIV-1BAL viruses without lectin, with mGRFT, with GRFT, or with one of the tandemers. Negative controls with buffers or purified lectin did not measurably scatter light.
Mentions: One of the common attributes of many lectins is their capacity to agglutinate pathogens [32]. Although antiviral lectins such as GRFT have been shown not to agglutinate human cells [14], it has been suggested that these lectins, which contain multiple binding domains, aggregate viruses [30]. To determine if this was true and to evaluate the role that the enhanced flexibility in binding domains may play in this phenomenon, we used dynamic light scattering to measure the aggregation of HIV-1BAL virions after treatment with mGRFT, GRFT, or one of the four GRFT tandemers. As shown in FigureĀ 4, GRFT did aggregate HIV-1BAL virions to a significant extent when compared to untreated virions. As expected, mGRFT, with only a single binding domain, did not aggregate virions but, interestingly, also none of the GRFT tandemers, including 4mGRFT with its four binding domains, caused virions to aggregate.Figure 4

Bottom Line: Previously, we have engineered and analyzed several monomeric forms of this lectin (mGRFT) with anti-HIV EC50 values ranging up to 323 nM.Based on our previous analysis of mGRFT, we hypothesized that the orientation and spacing of the carbohydrate binding domains GRFT were key to its antiviral activity.We also demonstrate by dynamic light scattering and cryo-electron microscopy that mGRFT tandemers do not aggregate HIV virions.

View Article: PubMed Central - PubMed

Affiliation: Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702-1201, USA. tinoush@umd.edu.

ABSTRACT

Background: The lectin griffithsin (GRFT) is a potent antiviral agent capable of prevention and treatment of infections caused by a number of enveloped viruses and is currently under development as an anti-HIV microbicide. In addition to its broad antiviral activity, GRFT is stable at high temperature and at a broad pH range, displays little toxicity and immunogenicity, and is amenable to large-scale manufacturing. Native GRFT is a domain-swapped homodimer that binds to viral envelope glycoproteins and has displayed mid-picomolar activity in cell-based anti-HIV assays. Previously, we have engineered and analyzed several monomeric forms of this lectin (mGRFT) with anti-HIV EC50 values ranging up to 323 nM. Based on our previous analysis of mGRFT, we hypothesized that the orientation and spacing of the carbohydrate binding domains GRFT were key to its antiviral activity.

Results: Here we present data on engineered tandem repeats of mGRFT (mGRFT tandemers) with antiviral activity at concentrations as low as one picomolar in whole-cell anti-HIV assays. mGRFT tandemers were analyzed thermodynamically, both individually and in complex with HIV-1 gp120. We also demonstrate by dynamic light scattering and cryo-electron microscopy that mGRFT tandemers do not aggregate HIV virions. This establishes that, although the intra-virion crosslinking of HIV envelope glycoproteins is likely integral to their activity, the antiviral activity of these lectins is not due to virus aggregation caused by inter-virion crosslinking.

Conclusions: The engineered tandemer constructs of mGRFT may provide novel and powerful agents for prevention of infection by HIV and other enveloped viruses.

Show MeSH
Related in: MedlinePlus