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Pilot Study on the Use of DNA Priming Immunization to Enhance Y. pestis LcrV-Specific B Cell Responses Elicited by a Recombinant LcrV Protein Vaccine.

Li W, Wang S, Lu S - Vaccines (Basel) (2013)

Bottom Line: However, there is limited information on the mechanism of this effect.Previously, we demonstrated that a DNA vaccine expressing LcrV antigen can protect mice from lethal mucosal challenge.The finding that DNA immunization can enhance antigen-specific B cell responses is highly significant and will help guide similar studies in other model antigen systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA. wei.li@umassmed.edu.

ABSTRACT
Recent studies indicate that DNA immunization is powerful in eliciting antigen-specific antibody responses in both animal and human studies. However, there is limited information on the mechanism of this effect. In particular, it is not known whether DNA immunization can also enhance the development of antigen-specific B cell development. In this report, a pilot study was conducted using plague LcrV immunogen as a model system to determine whether DNA immunization is able to enhance LcrV-specific B cell development in mice. Plague is an acute and often fatal infectious disease caused by Yersinia pestis (Y. pestis). Humoral immune responses provide critical protective immunity against plague. Previously, we demonstrated that a DNA vaccine expressing LcrV antigen can protect mice from lethal mucosal challenge. In the current study, we further evaluated whether the use of a DNA priming immunization is able to enhance the immunogenicity of a recombinant LcrV protein vaccine, and in particular, the development of LcrV-specific B cells. Our data indicate that DNA immunization was able to elicit high-level LcrV antibody responses when used alone or as part of a prime-boost immunization approach. Most significantly, DNA immunization was also able to increase the levels of LcrV-specific B cell development. The finding that DNA immunization can enhance antigen-specific B cell responses is highly significant and will help guide similar studies in other model antigen systems.

No MeSH data available.


Related in: MedlinePlus

V-specific antibody secreting cells (ASC) in fresh, 5-day cultured and 5-day stimulated splenocytes and bone marrow cells as measured by ELISPOT. Mice immunized with different V vaccine regimens in mice: codon optimized V DNA vaccine alone (V-DNA),V DNA vaccine prime followed by V protein boost formulated with IFA (V-DNA + Prot/IFA), V protein formulated with IFA (V-Prot/IFA), V protein alone (V-Prot), or empty DNA vaccine vector alone (Vector), as indicated. Panel A: Actual sample wells of V-specific ASC spots splenocytes (upper panel) or bone marrow cells (lower panel). Panel B: Frequency of V-specific ASC per million splenocytes in each group. Panel C: Frequency of V-specific ASC per million bone marrow cells in each group. Data represent the mean spot forming cells (SFCs)/million cells with standard deviation from 5 mice/group. The splenocytes and bone marrow cells were collected 12 weeks after the boost (2nd) immunization. Statistically significant differences (p < 0.05) are indicated as “*”, “#” or “^” when comparing V-DNA, V-DNA + Prot/IFA, and V-Prot/IFA groups.
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vaccines-02-00036-f006: V-specific antibody secreting cells (ASC) in fresh, 5-day cultured and 5-day stimulated splenocytes and bone marrow cells as measured by ELISPOT. Mice immunized with different V vaccine regimens in mice: codon optimized V DNA vaccine alone (V-DNA),V DNA vaccine prime followed by V protein boost formulated with IFA (V-DNA + Prot/IFA), V protein formulated with IFA (V-Prot/IFA), V protein alone (V-Prot), or empty DNA vaccine vector alone (Vector), as indicated. Panel A: Actual sample wells of V-specific ASC spots splenocytes (upper panel) or bone marrow cells (lower panel). Panel B: Frequency of V-specific ASC per million splenocytes in each group. Panel C: Frequency of V-specific ASC per million bone marrow cells in each group. Data represent the mean spot forming cells (SFCs)/million cells with standard deviation from 5 mice/group. The splenocytes and bone marrow cells were collected 12 weeks after the boost (2nd) immunization. Statistically significant differences (p < 0.05) are indicated as “*”, “#” or “^” when comparing V-DNA, V-DNA + Prot/IFA, and V-Prot/IFA groups.

Mentions: B cell ELISPOT analysis was conducted to measure LcrV-specific antibody secreting cells in the bone marrow and spleen of immunized mice. Fresh cells, cells cultured for five days without stimulation, and cells stimulated with LcrV antigen were used in this analysis (Figure 6). Figure 6A shows the representative ELISPOT pictures, which indicate that the overall frequency of LcrV-specific B cells in bone marrow was higher than that in the spleen. The recombinant LcrV protein vaccine alone group without adjuvant had the lowest levels of LcrV B cell responses in both bone marrow and spleen, which is compatible with observed antibody responses. When group average data was analyzed, the DNA prime-protein boost group had the highest LcrV B cell responses in spleen after stimulation, responses that were much higher than observed in the two LcrV protein groups (Figure 6B). In bone marrow, DNA vaccine groups generally had a higher number of LcrV B cells than protein vaccine groups, especially in fresh cells. However, due to the high variation in the B cell ELISPOT analysis in bone marrow cells, there was no statistically significant difference between DNA vaccine groups and protein groups in cultured or stimulated cells (Figure 6C).


Pilot Study on the Use of DNA Priming Immunization to Enhance Y. pestis LcrV-Specific B Cell Responses Elicited by a Recombinant LcrV Protein Vaccine.

Li W, Wang S, Lu S - Vaccines (Basel) (2013)

V-specific antibody secreting cells (ASC) in fresh, 5-day cultured and 5-day stimulated splenocytes and bone marrow cells as measured by ELISPOT. Mice immunized with different V vaccine regimens in mice: codon optimized V DNA vaccine alone (V-DNA),V DNA vaccine prime followed by V protein boost formulated with IFA (V-DNA + Prot/IFA), V protein formulated with IFA (V-Prot/IFA), V protein alone (V-Prot), or empty DNA vaccine vector alone (Vector), as indicated. Panel A: Actual sample wells of V-specific ASC spots splenocytes (upper panel) or bone marrow cells (lower panel). Panel B: Frequency of V-specific ASC per million splenocytes in each group. Panel C: Frequency of V-specific ASC per million bone marrow cells in each group. Data represent the mean spot forming cells (SFCs)/million cells with standard deviation from 5 mice/group. The splenocytes and bone marrow cells were collected 12 weeks after the boost (2nd) immunization. Statistically significant differences (p < 0.05) are indicated as “*”, “#” or “^” when comparing V-DNA, V-DNA + Prot/IFA, and V-Prot/IFA groups.
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Related In: Results  -  Collection

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vaccines-02-00036-f006: V-specific antibody secreting cells (ASC) in fresh, 5-day cultured and 5-day stimulated splenocytes and bone marrow cells as measured by ELISPOT. Mice immunized with different V vaccine regimens in mice: codon optimized V DNA vaccine alone (V-DNA),V DNA vaccine prime followed by V protein boost formulated with IFA (V-DNA + Prot/IFA), V protein formulated with IFA (V-Prot/IFA), V protein alone (V-Prot), or empty DNA vaccine vector alone (Vector), as indicated. Panel A: Actual sample wells of V-specific ASC spots splenocytes (upper panel) or bone marrow cells (lower panel). Panel B: Frequency of V-specific ASC per million splenocytes in each group. Panel C: Frequency of V-specific ASC per million bone marrow cells in each group. Data represent the mean spot forming cells (SFCs)/million cells with standard deviation from 5 mice/group. The splenocytes and bone marrow cells were collected 12 weeks after the boost (2nd) immunization. Statistically significant differences (p < 0.05) are indicated as “*”, “#” or “^” when comparing V-DNA, V-DNA + Prot/IFA, and V-Prot/IFA groups.
Mentions: B cell ELISPOT analysis was conducted to measure LcrV-specific antibody secreting cells in the bone marrow and spleen of immunized mice. Fresh cells, cells cultured for five days without stimulation, and cells stimulated with LcrV antigen were used in this analysis (Figure 6). Figure 6A shows the representative ELISPOT pictures, which indicate that the overall frequency of LcrV-specific B cells in bone marrow was higher than that in the spleen. The recombinant LcrV protein vaccine alone group without adjuvant had the lowest levels of LcrV B cell responses in both bone marrow and spleen, which is compatible with observed antibody responses. When group average data was analyzed, the DNA prime-protein boost group had the highest LcrV B cell responses in spleen after stimulation, responses that were much higher than observed in the two LcrV protein groups (Figure 6B). In bone marrow, DNA vaccine groups generally had a higher number of LcrV B cells than protein vaccine groups, especially in fresh cells. However, due to the high variation in the B cell ELISPOT analysis in bone marrow cells, there was no statistically significant difference between DNA vaccine groups and protein groups in cultured or stimulated cells (Figure 6C).

Bottom Line: However, there is limited information on the mechanism of this effect.Previously, we demonstrated that a DNA vaccine expressing LcrV antigen can protect mice from lethal mucosal challenge.The finding that DNA immunization can enhance antigen-specific B cell responses is highly significant and will help guide similar studies in other model antigen systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA. wei.li@umassmed.edu.

ABSTRACT
Recent studies indicate that DNA immunization is powerful in eliciting antigen-specific antibody responses in both animal and human studies. However, there is limited information on the mechanism of this effect. In particular, it is not known whether DNA immunization can also enhance the development of antigen-specific B cell development. In this report, a pilot study was conducted using plague LcrV immunogen as a model system to determine whether DNA immunization is able to enhance LcrV-specific B cell development in mice. Plague is an acute and often fatal infectious disease caused by Yersinia pestis (Y. pestis). Humoral immune responses provide critical protective immunity against plague. Previously, we demonstrated that a DNA vaccine expressing LcrV antigen can protect mice from lethal mucosal challenge. In the current study, we further evaluated whether the use of a DNA priming immunization is able to enhance the immunogenicity of a recombinant LcrV protein vaccine, and in particular, the development of LcrV-specific B cells. Our data indicate that DNA immunization was able to elicit high-level LcrV antibody responses when used alone or as part of a prime-boost immunization approach. Most significantly, DNA immunization was also able to increase the levels of LcrV-specific B cell development. The finding that DNA immunization can enhance antigen-specific B cell responses is highly significant and will help guide similar studies in other model antigen systems.

No MeSH data available.


Related in: MedlinePlus