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HIV-1 conserved elements p24CE DNA vaccine induces humoral immune responses with broad epitope recognition in macaques.

Kulkarni V, Valentin A, Rosati M, Rolland M, Mullins JI, Pavlakis GN, Felber BK - PLoS ONE (2014)

Bottom Line: In contrast, antibodies elicited by p55gag DNA vaccine failed to recognize p24CE protein and did not recognize linear epitopes spanning the CE.Interestingly, boosting of p24CE DNA primed animals with p55gag DNA resulted in augmentation of antibodies able to recognize p24gag as well as the p24CE proteins, thereby inducing broadest immunity.This novel and effective strategy to broaden responses could be applied against other antigens of highly diverse pathogens.

View Article: PubMed Central - PubMed

Affiliation: Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America.

ABSTRACT
To target immune responses towards invariable regions of the virus, we engineered DNA-based immunogens encoding conserved elements (CE) of HIV-1 p24gag. This conserved element vaccine is designed to avoid decoy epitopes by focusing responses to critical viral elements. We previously reported that vaccination of macaques with p24CE DNA induced robust cellular immune responses to CE that were not elicited upon wild type p55gag DNA vaccination. p24CE DNA priming followed by p55gag DNA boost provided a novel strategy to increase the magnitude and breadth of the cellular immune responses to HIV-1 Gag, including the induction of strong, multifunctional T-cell responses targeting epitopes within CE. Here, we examined the humoral responses induced upon p24CE DNA or p55gag DNA vaccination in macaques and found that although both vaccines induced robust p24gag binding antibody responses, the responses induced by p24CE DNA showed a unique broad range of linear epitope recognition. In contrast, antibodies elicited by p55gag DNA vaccine failed to recognize p24CE protein and did not recognize linear epitopes spanning the CE. Interestingly, boosting of p24CE DNA primed animals with p55gag DNA resulted in augmentation of antibodies able to recognize p24gag as well as the p24CE proteins, thereby inducing broadest immunity. Our results indicate that an effectively directed vaccine strategy that includes priming with the conserved element vaccine followed by boost with the complete immunogen induces broad cellular and humoral immunity focused on the conserved regions of the virus. This novel and effective strategy to broaden responses could be applied against other antigens of highly diverse pathogens.

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Related in: MedlinePlus

p24CE Expression plasmids.Cartoon depicting the HIV p55gag protein and its proteolytic cleavage products p17gag, p24gag and the C-terminal p2, p7, p1 and p6 proteins. The 7 highly conserved elements (CE) identified within p24Gag are indicated. The two p24CE constructs differ by 1 ‘toggle’ AA per CE, indicated by asterisks. The 7 CE were connected via linkers and the p24CE proteins were expressed from the CMV promoter using the mammalian expression vector pCMV.kan [18].
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pone-0111085-g001: p24CE Expression plasmids.Cartoon depicting the HIV p55gag protein and its proteolytic cleavage products p17gag, p24gag and the C-terminal p2, p7, p1 and p6 proteins. The 7 highly conserved elements (CE) identified within p24Gag are indicated. The two p24CE constructs differ by 1 ‘toggle’ AA per CE, indicated by asterisks. The 7 CE were connected via linkers and the p24CE proteins were expressed from the CMV promoter using the mammalian expression vector pCMV.kan [18].

Mentions: To focus the immune responses on nearly invariant regions of the HIV-1 proteome, we developed DNA immunogens encoding 7 highly conserved elements (CE) identified within HIV-1 p24gag[18], [19], [23]. Two plasmids were constructed with each of the 7 CE elements, which differed by 1 ‘toggle’ amino acid per CE to include a lesser conserved AA, and were arranged by taking into consideration the hydrophobicity of individual CE and spaced with linkers designed to maximize cleavage between the adjacent CE (Figure 1) as described previously [18], [19], [23]. Each 140-AA CE cassette, p24CE1 and p24CE2, was expressed from expression-optimized DNA vectors.


HIV-1 conserved elements p24CE DNA vaccine induces humoral immune responses with broad epitope recognition in macaques.

Kulkarni V, Valentin A, Rosati M, Rolland M, Mullins JI, Pavlakis GN, Felber BK - PLoS ONE (2014)

p24CE Expression plasmids.Cartoon depicting the HIV p55gag protein and its proteolytic cleavage products p17gag, p24gag and the C-terminal p2, p7, p1 and p6 proteins. The 7 highly conserved elements (CE) identified within p24Gag are indicated. The two p24CE constructs differ by 1 ‘toggle’ AA per CE, indicated by asterisks. The 7 CE were connected via linkers and the p24CE proteins were expressed from the CMV promoter using the mammalian expression vector pCMV.kan [18].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4206485&req=5

pone-0111085-g001: p24CE Expression plasmids.Cartoon depicting the HIV p55gag protein and its proteolytic cleavage products p17gag, p24gag and the C-terminal p2, p7, p1 and p6 proteins. The 7 highly conserved elements (CE) identified within p24Gag are indicated. The two p24CE constructs differ by 1 ‘toggle’ AA per CE, indicated by asterisks. The 7 CE were connected via linkers and the p24CE proteins were expressed from the CMV promoter using the mammalian expression vector pCMV.kan [18].
Mentions: To focus the immune responses on nearly invariant regions of the HIV-1 proteome, we developed DNA immunogens encoding 7 highly conserved elements (CE) identified within HIV-1 p24gag[18], [19], [23]. Two plasmids were constructed with each of the 7 CE elements, which differed by 1 ‘toggle’ amino acid per CE to include a lesser conserved AA, and were arranged by taking into consideration the hydrophobicity of individual CE and spaced with linkers designed to maximize cleavage between the adjacent CE (Figure 1) as described previously [18], [19], [23]. Each 140-AA CE cassette, p24CE1 and p24CE2, was expressed from expression-optimized DNA vectors.

Bottom Line: In contrast, antibodies elicited by p55gag DNA vaccine failed to recognize p24CE protein and did not recognize linear epitopes spanning the CE.Interestingly, boosting of p24CE DNA primed animals with p55gag DNA resulted in augmentation of antibodies able to recognize p24gag as well as the p24CE proteins, thereby inducing broadest immunity.This novel and effective strategy to broaden responses could be applied against other antigens of highly diverse pathogens.

View Article: PubMed Central - PubMed

Affiliation: Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America.

ABSTRACT
To target immune responses towards invariable regions of the virus, we engineered DNA-based immunogens encoding conserved elements (CE) of HIV-1 p24gag. This conserved element vaccine is designed to avoid decoy epitopes by focusing responses to critical viral elements. We previously reported that vaccination of macaques with p24CE DNA induced robust cellular immune responses to CE that were not elicited upon wild type p55gag DNA vaccination. p24CE DNA priming followed by p55gag DNA boost provided a novel strategy to increase the magnitude and breadth of the cellular immune responses to HIV-1 Gag, including the induction of strong, multifunctional T-cell responses targeting epitopes within CE. Here, we examined the humoral responses induced upon p24CE DNA or p55gag DNA vaccination in macaques and found that although both vaccines induced robust p24gag binding antibody responses, the responses induced by p24CE DNA showed a unique broad range of linear epitope recognition. In contrast, antibodies elicited by p55gag DNA vaccine failed to recognize p24CE protein and did not recognize linear epitopes spanning the CE. Interestingly, boosting of p24CE DNA primed animals with p55gag DNA resulted in augmentation of antibodies able to recognize p24gag as well as the p24CE proteins, thereby inducing broadest immunity. Our results indicate that an effectively directed vaccine strategy that includes priming with the conserved element vaccine followed by boost with the complete immunogen induces broad cellular and humoral immunity focused on the conserved regions of the virus. This novel and effective strategy to broaden responses could be applied against other antigens of highly diverse pathogens.

Show MeSH
Related in: MedlinePlus