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Identifying the Role of E2 Domains on Alphavirus Neutralization and Protective Immune Responses.

Weger-Lucarelli J, Aliota MT, Kamlangdee A, Osorio JE - PLoS Negl Trop Dis (2015)

Bottom Line: The alphavirus E2, the receptor-binding envelope protein, is considered to be the predominant target of the protective host immune response.Using chimeric viruses, it was determined that the alphavirus E2 domain B was the critical target of neutralizing antibodies in both mice and humans.Therefore, chimeric viruses may have more relevance for vaccine discovery than peptide-based approaches, which only detect linear epitopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

ABSTRACT

Background: Chikungunya virus (CHIKV) and other alphaviruses are the etiologic agents of numerous diseases in both humans and animals. Despite this, the viral mediators of protective immunity against alphaviruses are poorly understood, highlighted by the lack of a licensed human vaccine for any member of this virus genus. The alphavirus E2, the receptor-binding envelope protein, is considered to be the predominant target of the protective host immune response. Although envelope protein domains have been studied for vaccine and neutralization in flaviviruses, their role in alphaviruses is less characterized. Here, we describe the role of the alphavirus E2 domains in neutralization and protection through the use of chimeric viruses.

Methodology/principal findings: Four chimeric viruses were constructed in which individual E2 domains of CHIKV were replaced with the corresponding domain from Semliki Forest virus (SFV) (ΔDomA/ΔDomB/ΔDomC/ ΔDomA+B). Vaccination studies in mice (both live and inactivated virus) revealed that domain B was the primary determinant of neutralization. Neutralization studies with CHIKV immune serum from humans were consistent with mouse studies, as ΔDomB was poorly neutralized.

Conclusions/significance: Using chimeric viruses, it was determined that the alphavirus E2 domain B was the critical target of neutralizing antibodies in both mice and humans. Therefore, chimeric viruses may have more relevance for vaccine discovery than peptide-based approaches, which only detect linear epitopes. This study provides new insight into the role of alphavirus E2 domains on neutralization determinants and may be useful for the design of novel therapeutic technologies.

No MeSH data available.


Related in: MedlinePlus

Neutralization of parental and chimeric viruses with CHIKV-immune human serum.Convalescent serum samples from 10 human patients were collected aseptically. Neutralization was performed using plaque reduction neutralization 50 (PRNT50) test. Two-fold dilutions of serum samples were incubated individually with each parental (CHIKV or SFV) or chimeric virus (ΔDomA, ΔDomB or ΔDomC, ΔDomA+B). Cells were fixed 36 hours post-infection and stained with crystal violet solution to visualize plaques. Data is presented as the inverse of the final serum dilution that showed 50% reduction or greater in plaques.
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pntd.0004163.g006: Neutralization of parental and chimeric viruses with CHIKV-immune human serum.Convalescent serum samples from 10 human patients were collected aseptically. Neutralization was performed using plaque reduction neutralization 50 (PRNT50) test. Two-fold dilutions of serum samples were incubated individually with each parental (CHIKV or SFV) or chimeric virus (ΔDomA, ΔDomB or ΔDomC, ΔDomA+B). Cells were fixed 36 hours post-infection and stained with crystal violet solution to visualize plaques. Data is presented as the inverse of the final serum dilution that showed 50% reduction or greater in plaques.

Mentions: In order to validate our work in mice, convalescent human serum samples obtained from patients previously infected with CHIKV were tested for neutralization capacity of each of the parental (CHIKV and SFV) or chimeric viruses (ΔDomA/ΔDomB/ΔDomC/ΔDomA+B). Samples were isolated from 10 volunteers during the current outbreak from Martinique or Colombia. As expected, the highest neutralization titers were observed against CHIKV, while little to no neutralization was observed against SFV (Fig 6). ΔDomA and ΔDomC viruses had high neutralizing titers against CHIKV. In contrast, ΔDomB and ΔDomA+B were neutralized at a significantly lower capacity than CHIKV or ΔDomA (p<0.01). These data indicated that domain B is critical for effective neutralization of CHIKV.


Identifying the Role of E2 Domains on Alphavirus Neutralization and Protective Immune Responses.

Weger-Lucarelli J, Aliota MT, Kamlangdee A, Osorio JE - PLoS Negl Trop Dis (2015)

Neutralization of parental and chimeric viruses with CHIKV-immune human serum.Convalescent serum samples from 10 human patients were collected aseptically. Neutralization was performed using plaque reduction neutralization 50 (PRNT50) test. Two-fold dilutions of serum samples were incubated individually with each parental (CHIKV or SFV) or chimeric virus (ΔDomA, ΔDomB or ΔDomC, ΔDomA+B). Cells were fixed 36 hours post-infection and stained with crystal violet solution to visualize plaques. Data is presented as the inverse of the final serum dilution that showed 50% reduction or greater in plaques.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608762&req=5

pntd.0004163.g006: Neutralization of parental and chimeric viruses with CHIKV-immune human serum.Convalescent serum samples from 10 human patients were collected aseptically. Neutralization was performed using plaque reduction neutralization 50 (PRNT50) test. Two-fold dilutions of serum samples were incubated individually with each parental (CHIKV or SFV) or chimeric virus (ΔDomA, ΔDomB or ΔDomC, ΔDomA+B). Cells were fixed 36 hours post-infection and stained with crystal violet solution to visualize plaques. Data is presented as the inverse of the final serum dilution that showed 50% reduction or greater in plaques.
Mentions: In order to validate our work in mice, convalescent human serum samples obtained from patients previously infected with CHIKV were tested for neutralization capacity of each of the parental (CHIKV and SFV) or chimeric viruses (ΔDomA/ΔDomB/ΔDomC/ΔDomA+B). Samples were isolated from 10 volunteers during the current outbreak from Martinique or Colombia. As expected, the highest neutralization titers were observed against CHIKV, while little to no neutralization was observed against SFV (Fig 6). ΔDomA and ΔDomC viruses had high neutralizing titers against CHIKV. In contrast, ΔDomB and ΔDomA+B were neutralized at a significantly lower capacity than CHIKV or ΔDomA (p<0.01). These data indicated that domain B is critical for effective neutralization of CHIKV.

Bottom Line: The alphavirus E2, the receptor-binding envelope protein, is considered to be the predominant target of the protective host immune response.Using chimeric viruses, it was determined that the alphavirus E2 domain B was the critical target of neutralizing antibodies in both mice and humans.Therefore, chimeric viruses may have more relevance for vaccine discovery than peptide-based approaches, which only detect linear epitopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

ABSTRACT

Background: Chikungunya virus (CHIKV) and other alphaviruses are the etiologic agents of numerous diseases in both humans and animals. Despite this, the viral mediators of protective immunity against alphaviruses are poorly understood, highlighted by the lack of a licensed human vaccine for any member of this virus genus. The alphavirus E2, the receptor-binding envelope protein, is considered to be the predominant target of the protective host immune response. Although envelope protein domains have been studied for vaccine and neutralization in flaviviruses, their role in alphaviruses is less characterized. Here, we describe the role of the alphavirus E2 domains in neutralization and protection through the use of chimeric viruses.

Methodology/principal findings: Four chimeric viruses were constructed in which individual E2 domains of CHIKV were replaced with the corresponding domain from Semliki Forest virus (SFV) (ΔDomA/ΔDomB/ΔDomC/ ΔDomA+B). Vaccination studies in mice (both live and inactivated virus) revealed that domain B was the primary determinant of neutralization. Neutralization studies with CHIKV immune serum from humans were consistent with mouse studies, as ΔDomB was poorly neutralized.

Conclusions/significance: Using chimeric viruses, it was determined that the alphavirus E2 domain B was the critical target of neutralizing antibodies in both mice and humans. Therefore, chimeric viruses may have more relevance for vaccine discovery than peptide-based approaches, which only detect linear epitopes. This study provides new insight into the role of alphavirus E2 domains on neutralization determinants and may be useful for the design of novel therapeutic technologies.

No MeSH data available.


Related in: MedlinePlus