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Bat and pig IFN-induced transmembrane protein 3 restrict cell entry by influenza virus and lyssaviruses.

Benfield CT, Smith SE, Wright E, Wash RS, Ferrara F, Temperton NJ, Kellam P - J. Gen. Virol. (2015)

Bottom Line: Ectopically expressed pig and microbat IFITM3 co-localized with transferrin (early endosomes) and CD63 (late endosomes/multivesicular bodies).Pig and microbat IFITM3 restricted cell entry mediated by multiple influenza haemagglutinin subtypes and lyssavirus glycoproteins.In summary, we showed that IFITMs function as potent broad-spectrum antiviral effectors in two mammals - pigs and bats - identified as major reservoirs for emerging viruses.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Pathogen Biology, The Royal Veterinary College, Hatfield, UK cbenfield@rvc.ac.uk.

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siRNA knockdown of IFITM3 in pig and microbat cells enhances influenza virus replication. Pig NPTr or microbat cells were transfected with siRNA targeting IFITM3 or control siRNA prior to quantification of IFITM3 by qRT-PCR (a, e) or infection with influenza A/WSN/33. Virus yields were measured by plaque assay (b, f) or NP expression was measured using flow cytometry (c, d, g). NPTr cells were either stimulated with poly(I : C) for 2 h before infection (m.o.i. 0.01) and analysed at 36 h post-infection (b, c) or cells were infected in the absence of poly(I : C). Results are shown as means±sd for biological triplicates assayed in duplicate and data are representative of two independent experiments. *P<0.05; **P<0.01 (Student’s t-test).
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f8: siRNA knockdown of IFITM3 in pig and microbat cells enhances influenza virus replication. Pig NPTr or microbat cells were transfected with siRNA targeting IFITM3 or control siRNA prior to quantification of IFITM3 by qRT-PCR (a, e) or infection with influenza A/WSN/33. Virus yields were measured by plaque assay (b, f) or NP expression was measured using flow cytometry (c, d, g). NPTr cells were either stimulated with poly(I : C) for 2 h before infection (m.o.i. 0.01) and analysed at 36 h post-infection (b, c) or cells were infected in the absence of poly(I : C). Results are shown as means±sd for biological triplicates assayed in duplicate and data are representative of two independent experiments. *P<0.05; **P<0.01 (Student’s t-test).

Mentions: Next, the function of endogenous IFITM3 was assessed using small interfering RNA (siRNA) designed using the RACE sequence data to target IFITM3 and not other putative IFITM paralogues. siRNA targeting IFITM3 or control non-targeting siRNAs were transfected into cells with poly(I : C) induction of IFITM3. IFITM3 mRNA was quantified by qRT-PCR and the biological effect of the knockdown assessed by infection with influenza A/WSN/33 (Fig. 8). Transfection of siRNA against pig IFITM3 led to a 63 % knockdown in IFITM3 mRNA (fold change of 1.4 log2) (Fig. 8a), a 3.4-fold increase in virus yield (Fig. 8b) and a twofold increase in the proportion of influenza NP-positive cells (Fig. 8c) relative to control siRNA-transfected cells. In the absence of poly(I : C) stimulation, IFITM3 knockdown in NPTr cells increased influenza NP-positive cells more (3.3-fold) (Fig. 8d), suggesting that additional poly(I : C)-induced genes complement IFITM3-mediated influenza virus restriction. Microbat IFITM3 knockdown in the absence of poly(I : C) stimulation (Fig. 8e–g) reduced IFITM3 mRNA levels by 60 % (fold change of 1.3 log2) (Fig. 8e) and led to a twofold increase in infectious yields (Fig. 8f) and a threefold increase in NP expression (Fig. 8g), relative to control siRNA transfection. Thus, endogenous IFITM3 in pig tracheal NPTr cells and microbat lung cells restricts influenza virus. Lastly, following siRNA knockdown of baseline IFITM3 in a microbat cell line, overexpression of microbat IFITM3 significantly inhibited influenza NP expression (Fig. S4).


Bat and pig IFN-induced transmembrane protein 3 restrict cell entry by influenza virus and lyssaviruses.

Benfield CT, Smith SE, Wright E, Wash RS, Ferrara F, Temperton NJ, Kellam P - J. Gen. Virol. (2015)

siRNA knockdown of IFITM3 in pig and microbat cells enhances influenza virus replication. Pig NPTr or microbat cells were transfected with siRNA targeting IFITM3 or control siRNA prior to quantification of IFITM3 by qRT-PCR (a, e) or infection with influenza A/WSN/33. Virus yields were measured by plaque assay (b, f) or NP expression was measured using flow cytometry (c, d, g). NPTr cells were either stimulated with poly(I : C) for 2 h before infection (m.o.i. 0.01) and analysed at 36 h post-infection (b, c) or cells were infected in the absence of poly(I : C). Results are shown as means±sd for biological triplicates assayed in duplicate and data are representative of two independent experiments. *P<0.05; **P<0.01 (Student’s t-test).
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Related In: Results  -  Collection

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f8: siRNA knockdown of IFITM3 in pig and microbat cells enhances influenza virus replication. Pig NPTr or microbat cells were transfected with siRNA targeting IFITM3 or control siRNA prior to quantification of IFITM3 by qRT-PCR (a, e) or infection with influenza A/WSN/33. Virus yields were measured by plaque assay (b, f) or NP expression was measured using flow cytometry (c, d, g). NPTr cells were either stimulated with poly(I : C) for 2 h before infection (m.o.i. 0.01) and analysed at 36 h post-infection (b, c) or cells were infected in the absence of poly(I : C). Results are shown as means±sd for biological triplicates assayed in duplicate and data are representative of two independent experiments. *P<0.05; **P<0.01 (Student’s t-test).
Mentions: Next, the function of endogenous IFITM3 was assessed using small interfering RNA (siRNA) designed using the RACE sequence data to target IFITM3 and not other putative IFITM paralogues. siRNA targeting IFITM3 or control non-targeting siRNAs were transfected into cells with poly(I : C) induction of IFITM3. IFITM3 mRNA was quantified by qRT-PCR and the biological effect of the knockdown assessed by infection with influenza A/WSN/33 (Fig. 8). Transfection of siRNA against pig IFITM3 led to a 63 % knockdown in IFITM3 mRNA (fold change of 1.4 log2) (Fig. 8a), a 3.4-fold increase in virus yield (Fig. 8b) and a twofold increase in the proportion of influenza NP-positive cells (Fig. 8c) relative to control siRNA-transfected cells. In the absence of poly(I : C) stimulation, IFITM3 knockdown in NPTr cells increased influenza NP-positive cells more (3.3-fold) (Fig. 8d), suggesting that additional poly(I : C)-induced genes complement IFITM3-mediated influenza virus restriction. Microbat IFITM3 knockdown in the absence of poly(I : C) stimulation (Fig. 8e–g) reduced IFITM3 mRNA levels by 60 % (fold change of 1.3 log2) (Fig. 8e) and led to a twofold increase in infectious yields (Fig. 8f) and a threefold increase in NP expression (Fig. 8g), relative to control siRNA transfection. Thus, endogenous IFITM3 in pig tracheal NPTr cells and microbat lung cells restricts influenza virus. Lastly, following siRNA knockdown of baseline IFITM3 in a microbat cell line, overexpression of microbat IFITM3 significantly inhibited influenza NP expression (Fig. S4).

Bottom Line: Ectopically expressed pig and microbat IFITM3 co-localized with transferrin (early endosomes) and CD63 (late endosomes/multivesicular bodies).Pig and microbat IFITM3 restricted cell entry mediated by multiple influenza haemagglutinin subtypes and lyssavirus glycoproteins.In summary, we showed that IFITMs function as potent broad-spectrum antiviral effectors in two mammals - pigs and bats - identified as major reservoirs for emerging viruses.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Pathogen Biology, The Royal Veterinary College, Hatfield, UK cbenfield@rvc.ac.uk.

Show MeSH
Related in: MedlinePlus