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Early neutralizing IgG response to Chikungunya virus in infected patients targets a dominant linear epitope on the E2 glycoprotein.

Kam YW, Lum FM, Teo TH, Lee WW, Simarmata D, Harjanto S, Chua CL, Chan YF, Wee JK, Chow A, Lin RT, Leo YS, Le Grand R, Sam IC, Tong JC, Roques P, Wiesmüller KH, Rénia L, Rötzschke O, Ng LF - EMBO Mol Med (2012)

Bottom Line: E2EP3 is located at the N-terminus of the E2 glycoprotein and prominently exposed on the viral envelope.Screening of E2EP3 across different patient cohorts and in non-human primates demonstrated the value of this epitope as a good serology detection marker for CHIKV infection already at an early stage.Mice vaccinated by E2EP3 peptides were protected against CHIKV with reduced viremia and joint inflammation, providing a pre-clinical basis for the design of effective vaccine against arthralgia-inducing CHIKV and other alphaviruses.

View Article: PubMed Central - PubMed

Affiliation: Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore.

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Protection against CHIKV challenge in mice vaccinated with E2EP3 peptideIn vitro neutralizing activity of E2EP3-vaccinated mouse sera. Mice were immunized with E2EP3 peptide complex to KLH or PBS Control emulsified with Complete Freund's Adjuvant (CFA) subcutaneously, and were boosted two more times with Incomplete Freund's Adjuvant (IFA). Sera was collected at 27 days post-vaccination and assayed for in vitro neutralization at a dilution of 1:100 (n = 3). Results are expressed as percentage infection relative to PBS Control. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Mice immunized with E2EP3 or PBS Control were challenged subcutaneously with 106 PFU CHIKV (SGP11). CHIKV viremia was measured at 2 days post-challenge by virus plaque assay. The detection limit was 1000 pfu/ml. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Disease score measurement. Footpad sizes from day 0 to day 14 post-challenge were quantified by [width × thickness]. Footpad swelling (inflammation) relative to day 0 was obtained with the formula: [(day x − day 0) ÷ day 0], where x represents footpad sizes from day 1 to day 14. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.
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fig08: Protection against CHIKV challenge in mice vaccinated with E2EP3 peptideIn vitro neutralizing activity of E2EP3-vaccinated mouse sera. Mice were immunized with E2EP3 peptide complex to KLH or PBS Control emulsified with Complete Freund's Adjuvant (CFA) subcutaneously, and were boosted two more times with Incomplete Freund's Adjuvant (IFA). Sera was collected at 27 days post-vaccination and assayed for in vitro neutralization at a dilution of 1:100 (n = 3). Results are expressed as percentage infection relative to PBS Control. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Mice immunized with E2EP3 or PBS Control were challenged subcutaneously with 106 PFU CHIKV (SGP11). CHIKV viremia was measured at 2 days post-challenge by virus plaque assay. The detection limit was 1000 pfu/ml. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Disease score measurement. Footpad sizes from day 0 to day 14 post-challenge were quantified by [width × thickness]. Footpad swelling (inflammation) relative to day 0 was obtained with the formula: [(day x − day 0) ÷ day 0], where x represents footpad sizes from day 1 to day 14. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.

Mentions: The potential of E2EP3 epitope as a vaccine target was further assessed in a mouse model (Gardner et al, 2010). For this, C57BL/6 mice were vaccinated with E2EP3 covalently linked to KLH in the presence of Freund's Adjuvant. Mice were primed and boosted twice with the immunogen (emulsified first with Complete [CFA] and then with Incomplete Freund's Adjuvant [IFA]) over a period of 21 days. Significant anti-E2EP3 titer was detected 19 days post-vaccination after the 1st boost (Supporting information Figs 2C and 5A) and was further increased after the 2nd boost at 27 days post-vaccination (Supporting information Fig 5B). Importantly, the sera obtained at 27 days post-vaccination were able to neutralize CHIKV-infection in vitro. Compared to the PBS-vaccinated control group, infectivity was reduced by approximately 40% (Fig 8A). Moreover, virus challenge in mice at 30 days post-vaccination indicated a partial protection by E2EP3 as viremia was reduced from 4500 to 2000 pfu/ml at 2 days post-challenge (Fig 8B). This reduction of virus titer was also reflected in clinical symptoms used to monitor the virus-induced inflammation (Supporting information Fig 5C). Maximal footpad swelling in the PBS-vaccinated group was more than twice as that of the E2EP3-vaccinated group (Fig 8C). E2EP3 may therefore be used both as a marker as well as a potential vaccine component in pre-clinical models for CHIKV therapy.


Early neutralizing IgG response to Chikungunya virus in infected patients targets a dominant linear epitope on the E2 glycoprotein.

Kam YW, Lum FM, Teo TH, Lee WW, Simarmata D, Harjanto S, Chua CL, Chan YF, Wee JK, Chow A, Lin RT, Leo YS, Le Grand R, Sam IC, Tong JC, Roques P, Wiesmüller KH, Rénia L, Rötzschke O, Ng LF - EMBO Mol Med (2012)

Protection against CHIKV challenge in mice vaccinated with E2EP3 peptideIn vitro neutralizing activity of E2EP3-vaccinated mouse sera. Mice were immunized with E2EP3 peptide complex to KLH or PBS Control emulsified with Complete Freund's Adjuvant (CFA) subcutaneously, and were boosted two more times with Incomplete Freund's Adjuvant (IFA). Sera was collected at 27 days post-vaccination and assayed for in vitro neutralization at a dilution of 1:100 (n = 3). Results are expressed as percentage infection relative to PBS Control. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Mice immunized with E2EP3 or PBS Control were challenged subcutaneously with 106 PFU CHIKV (SGP11). CHIKV viremia was measured at 2 days post-challenge by virus plaque assay. The detection limit was 1000 pfu/ml. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Disease score measurement. Footpad sizes from day 0 to day 14 post-challenge were quantified by [width × thickness]. Footpad swelling (inflammation) relative to day 0 was obtained with the formula: [(day x − day 0) ÷ day 0], where x represents footpad sizes from day 1 to day 14. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.
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fig08: Protection against CHIKV challenge in mice vaccinated with E2EP3 peptideIn vitro neutralizing activity of E2EP3-vaccinated mouse sera. Mice were immunized with E2EP3 peptide complex to KLH or PBS Control emulsified with Complete Freund's Adjuvant (CFA) subcutaneously, and were boosted two more times with Incomplete Freund's Adjuvant (IFA). Sera was collected at 27 days post-vaccination and assayed for in vitro neutralization at a dilution of 1:100 (n = 3). Results are expressed as percentage infection relative to PBS Control. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Mice immunized with E2EP3 or PBS Control were challenged subcutaneously with 106 PFU CHIKV (SGP11). CHIKV viremia was measured at 2 days post-challenge by virus plaque assay. The detection limit was 1000 pfu/ml. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.Disease score measurement. Footpad sizes from day 0 to day 14 post-challenge were quantified by [width × thickness]. Footpad swelling (inflammation) relative to day 0 was obtained with the formula: [(day x − day 0) ÷ day 0], where x represents footpad sizes from day 1 to day 14. Data are presented as mean ± SD. *p < 0.05 by Mann–Whitney U test.
Mentions: The potential of E2EP3 epitope as a vaccine target was further assessed in a mouse model (Gardner et al, 2010). For this, C57BL/6 mice were vaccinated with E2EP3 covalently linked to KLH in the presence of Freund's Adjuvant. Mice were primed and boosted twice with the immunogen (emulsified first with Complete [CFA] and then with Incomplete Freund's Adjuvant [IFA]) over a period of 21 days. Significant anti-E2EP3 titer was detected 19 days post-vaccination after the 1st boost (Supporting information Figs 2C and 5A) and was further increased after the 2nd boost at 27 days post-vaccination (Supporting information Fig 5B). Importantly, the sera obtained at 27 days post-vaccination were able to neutralize CHIKV-infection in vitro. Compared to the PBS-vaccinated control group, infectivity was reduced by approximately 40% (Fig 8A). Moreover, virus challenge in mice at 30 days post-vaccination indicated a partial protection by E2EP3 as viremia was reduced from 4500 to 2000 pfu/ml at 2 days post-challenge (Fig 8B). This reduction of virus titer was also reflected in clinical symptoms used to monitor the virus-induced inflammation (Supporting information Fig 5C). Maximal footpad swelling in the PBS-vaccinated group was more than twice as that of the E2EP3-vaccinated group (Fig 8C). E2EP3 may therefore be used both as a marker as well as a potential vaccine component in pre-clinical models for CHIKV therapy.

Bottom Line: E2EP3 is located at the N-terminus of the E2 glycoprotein and prominently exposed on the viral envelope.Screening of E2EP3 across different patient cohorts and in non-human primates demonstrated the value of this epitope as a good serology detection marker for CHIKV infection already at an early stage.Mice vaccinated by E2EP3 peptides were protected against CHIKV with reduced viremia and joint inflammation, providing a pre-clinical basis for the design of effective vaccine against arthralgia-inducing CHIKV and other alphaviruses.

View Article: PubMed Central - PubMed

Affiliation: Singapore Immunology Network, Agency for Science, Technology and Research (A*STAR), Biopolis, Singapore.

Show MeSH
Related in: MedlinePlus