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Porcine type I interferons: polymorphic sequences and activity against PRRSV.

Sang Y, Rowland RR, Blecha F - BMC Proc (2011)

Bottom Line: Approximately 50% of the nucleotide changes were mutations that resulted in non-conserved amino acid substitution, as well as deletions that produced frame shifts in the open reading frames (ORFs).Polymorphic mutations are more common in multiple-member subtypes than single-member subtypes, and most are found within the IFN-α subclass.Some polymorphic isoforms have altered amino acid composition and shifted ORFs, which show significantly different antiviral activity in vitro.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA. blecha@vet.k-state.edu.

ABSTRACT

Background: Type I interferons (IFN) are a heterogeneous group of cytokines central to innate and adaptive antiviral immune responses. We have recently reported that porcine type I IFNs comprise at least 39 functional genes with diverse antiviral activity against porcine reproductive and respiratory syndrome virus (PRRSV). Here we report that potential cytokine polymorphisms exist in several genes of porcine type I IFNs.

Results: We have detected more than 100 potential polymorphic mutations, which include nucleotide substitutions and deletions, within the coding regions of porcine type I IFNs. Approximately 50% of the nucleotide changes were mutations that resulted in non-conserved amino acid substitution, as well as deletions that produced frame shifts in the open reading frames (ORFs). We have identified more than 20 polymorphic mutants that showed alterations in anti-PRRSV and anti-vesicular stomatitis virus (VSV) activity in vitro. In particular, some mutations in IFN-α2, IFN-α3, IFN-α8, IFN-α12 and IFN-ω5 significantly altered the antiviral activity of expressed proteins in comparison to the wild-type or variant with more similarity to the wild-type.

Conclusions: Multiple polymorphic isoforms potentially exist within subtypes of the porcine type I IFN family. Polymorphic mutations are more common in multiple-member subtypes than single-member subtypes, and most are found within the IFN-α subclass. Some polymorphic isoforms have altered amino acid composition and shifted ORFs, which show significantly different antiviral activity in vitro.

No MeSH data available.


Related in: MedlinePlus

Differential antiviral activity among polymorphic isoforms of some subtypes of porcine type I IFNs. Antiviral activity against PRRSV and VSV was evaluated as described in Sang et al., 2010 [11], and analyzed based on individual polymorphic isoforms. Authentic expression of individual IFN peptides was confirmed by gel electrophoresis. Peptide concentrations were adjusted to 2 μg/ml to ensure the antiviral differences were not a result of peptide levels in the antiviral assays. Antiviral activity of overexpressed IFN peptides was assayed as the inhibition of virus cytopathic effect, in which 1 unit (U) is defined as the highest dilution that reduced cell loss by 50% according to the Reed-Muench method. Data are means from four duplicates of two independent experiments. *p<0.05, n=4.
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Figure 1: Differential antiviral activity among polymorphic isoforms of some subtypes of porcine type I IFNs. Antiviral activity against PRRSV and VSV was evaluated as described in Sang et al., 2010 [11], and analyzed based on individual polymorphic isoforms. Authentic expression of individual IFN peptides was confirmed by gel electrophoresis. Peptide concentrations were adjusted to 2 μg/ml to ensure the antiviral differences were not a result of peptide levels in the antiviral assays. Antiviral activity of overexpressed IFN peptides was assayed as the inhibition of virus cytopathic effect, in which 1 unit (U) is defined as the highest dilution that reduced cell loss by 50% according to the Reed-Muench method. Data are means from four duplicates of two independent experiments. *p<0.05, n=4.

Mentions: Using IFN polypeptides expressed in a mammalian cell system [11], eight polymorphic IFNs showed altered antiviral activity against both PRRSV and VSV in vitro considering the different effects of cytopathic inhibition with the same amount of peptides. In comparison to the wild-type or the variant with more similarity to the wild-type, residual substitution of Leu40-Phe and Cys109-Arg in IFN-α2-1, Lys145-Glu in IFN-α3-1, deletion of Arg46 in IFN-α8μ, Phe88-Ser in IFN-α10-1, and Cys52-Arg in IFN-ω5-1, dramatically reduced antiviral activity against both PRRSV and VSV. The mutations had a more profound effect on reducing anti-PRRSV activity in MARC-145 cells than anti-VSV activity in PK-15 cells (Fig. 1). In addition, deletion mutants, such as IFN-α8μ and IFN-α12μ which are more atypical in their peptide sequence, showed little antiviral activity in both virus-cell systems. Because polymorphism among porcine type I IFN genes may represent an important factor for determining the outcome of the host-virus interaction, it will be informative to correlate IFN polymorphism in pigs with susceptibility to PRRSV and severity of PRRSV infection.


Porcine type I interferons: polymorphic sequences and activity against PRRSV.

Sang Y, Rowland RR, Blecha F - BMC Proc (2011)

Differential antiviral activity among polymorphic isoforms of some subtypes of porcine type I IFNs. Antiviral activity against PRRSV and VSV was evaluated as described in Sang et al., 2010 [11], and analyzed based on individual polymorphic isoforms. Authentic expression of individual IFN peptides was confirmed by gel electrophoresis. Peptide concentrations were adjusted to 2 μg/ml to ensure the antiviral differences were not a result of peptide levels in the antiviral assays. Antiviral activity of overexpressed IFN peptides was assayed as the inhibition of virus cytopathic effect, in which 1 unit (U) is defined as the highest dilution that reduced cell loss by 50% according to the Reed-Muench method. Data are means from four duplicates of two independent experiments. *p<0.05, n=4.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108238&req=5

Figure 1: Differential antiviral activity among polymorphic isoforms of some subtypes of porcine type I IFNs. Antiviral activity against PRRSV and VSV was evaluated as described in Sang et al., 2010 [11], and analyzed based on individual polymorphic isoforms. Authentic expression of individual IFN peptides was confirmed by gel electrophoresis. Peptide concentrations were adjusted to 2 μg/ml to ensure the antiviral differences were not a result of peptide levels in the antiviral assays. Antiviral activity of overexpressed IFN peptides was assayed as the inhibition of virus cytopathic effect, in which 1 unit (U) is defined as the highest dilution that reduced cell loss by 50% according to the Reed-Muench method. Data are means from four duplicates of two independent experiments. *p<0.05, n=4.
Mentions: Using IFN polypeptides expressed in a mammalian cell system [11], eight polymorphic IFNs showed altered antiviral activity against both PRRSV and VSV in vitro considering the different effects of cytopathic inhibition with the same amount of peptides. In comparison to the wild-type or the variant with more similarity to the wild-type, residual substitution of Leu40-Phe and Cys109-Arg in IFN-α2-1, Lys145-Glu in IFN-α3-1, deletion of Arg46 in IFN-α8μ, Phe88-Ser in IFN-α10-1, and Cys52-Arg in IFN-ω5-1, dramatically reduced antiviral activity against both PRRSV and VSV. The mutations had a more profound effect on reducing anti-PRRSV activity in MARC-145 cells than anti-VSV activity in PK-15 cells (Fig. 1). In addition, deletion mutants, such as IFN-α8μ and IFN-α12μ which are more atypical in their peptide sequence, showed little antiviral activity in both virus-cell systems. Because polymorphism among porcine type I IFN genes may represent an important factor for determining the outcome of the host-virus interaction, it will be informative to correlate IFN polymorphism in pigs with susceptibility to PRRSV and severity of PRRSV infection.

Bottom Line: Approximately 50% of the nucleotide changes were mutations that resulted in non-conserved amino acid substitution, as well as deletions that produced frame shifts in the open reading frames (ORFs).Polymorphic mutations are more common in multiple-member subtypes than single-member subtypes, and most are found within the IFN-α subclass.Some polymorphic isoforms have altered amino acid composition and shifted ORFs, which show significantly different antiviral activity in vitro.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA. blecha@vet.k-state.edu.

ABSTRACT

Background: Type I interferons (IFN) are a heterogeneous group of cytokines central to innate and adaptive antiviral immune responses. We have recently reported that porcine type I IFNs comprise at least 39 functional genes with diverse antiviral activity against porcine reproductive and respiratory syndrome virus (PRRSV). Here we report that potential cytokine polymorphisms exist in several genes of porcine type I IFNs.

Results: We have detected more than 100 potential polymorphic mutations, which include nucleotide substitutions and deletions, within the coding regions of porcine type I IFNs. Approximately 50% of the nucleotide changes were mutations that resulted in non-conserved amino acid substitution, as well as deletions that produced frame shifts in the open reading frames (ORFs). We have identified more than 20 polymorphic mutants that showed alterations in anti-PRRSV and anti-vesicular stomatitis virus (VSV) activity in vitro. In particular, some mutations in IFN-α2, IFN-α3, IFN-α8, IFN-α12 and IFN-ω5 significantly altered the antiviral activity of expressed proteins in comparison to the wild-type or variant with more similarity to the wild-type.

Conclusions: Multiple polymorphic isoforms potentially exist within subtypes of the porcine type I IFN family. Polymorphic mutations are more common in multiple-member subtypes than single-member subtypes, and most are found within the IFN-α subclass. Some polymorphic isoforms have altered amino acid composition and shifted ORFs, which show significantly different antiviral activity in vitro.

No MeSH data available.


Related in: MedlinePlus