DNA and modified vaccinia virus Ankara vaccines encoding multiple cytotoxic and helper T-lymphocyte epitopes of human immunodeficiency virus type 1 (HIV-1) are safe but weakly immunogenic in HIV-1-uninfected, vaccinia virus-naive adults

Design and evaluation of a multi-epitope DNA vaccine against HPV16

Cervical cancer, among the deadliest cancers affecting women globally, primarily arises from persistent infection with high-risk human papillomavirus (HPV). To effectively combat persistent infection and prevent the progression of precancerous lesions into malignancy, a therapeutic HPV vaccine is under development. This study utilized an immunoinformatics approach to predict epitopes of cytotoxic T lymphocytes (CTLs) and helper T lymphocytes (HTLs) using the E6 and E7 oncoproteins of the HPV16 strain as target antigens. Subsequently, through meticulous selection of T-cell epitopes and other necessary elements, a multi-epitope vaccine was constructed, exhibiting good immunogenic, physicochemical, and structural characteristics. Furthermore, in silico simulations showed that the vaccine not only interacted well with toll-like receptors (TLR2/TLR3/TLR4), but also induced a strong innate and adaptive immune response characterized by elevated Th1-type cytokines, such as interferon-gamma (IFN-γ) and interleukin-2 (IL2). Additionally, our study investigated the effects of different immunization intervals on immune responses, aiming to optimize a time-efficient immunization program. In animal model experiments, the vaccine exhibited robust immunogenic, therapeutic, and prophylactic effects. Administered thrice, it consistently induced the expansion of specific CD4 and CD8 T cells, resulting in substantial cytokines release and increased proliferation of memory T cell subsets in splenic cells. Overall, our findings support the potential of this multi-epitope vaccine in combating HPV16 infection and signify its candidacy for future HPV vaccine development.

Cervico-Vaginal Inflammatory Cytokine and Chemokine Responses to Two Different SIV Immunogens

Studies have shown that vaccine vectors and route of immunization can differentially activate different arms of the immune system. However, the effects of different HIV vaccine immunogens on mucosal inflammation have not yet been studied. Because mucosal sites are the primary route of HIV infection, we evaluated the cervico-vaginal inflammatory cytokine and chemokine levels of Mauritian cynomolgus macaques following immunization and boost using two different SIV vaccine immunogens. The PCS vaccine delivers 12 20-amino acid peptides overlapping the 12 protease cleavage sites, and the Gag/Env vaccine delivers the full Gag and full Env proteins of simian immunodeficiency virus. We showed that the PCS vaccine prime and boosts induced short-lived, lower level increases of a few pro-inflammatory/chemotactic cytokines. In the PCS-vaccine group only the levels of MCP-1 were significantly increased above the baseline (P = 0.0078, Week 6; P = 0.0078, Week 17; P = 0.0234; Week 51) following multiple boosts. In contrast, immunizations with the Gag/Env vaccine persistently increased the levels of multiple cytokines/chemokines. In the Gag/Env group, higher than baseline levels were consistently observed for IL-8 (P = 0.0078, Week 16; P = 0.0078, Week 17; P = 0.0156, Week 52), IL-1β (P = 0.0234, Week 16; P = 0.0156, Week 17; P = 0.0156, Week 52), and MIP-1α (P = 0.0313, Week 16; P = 0.0156, Week 17; P = 0.0313, Week 52). Over time, repeated boosts altered the relative levels of these cytokines between the Gag/Env and PCS vaccine group. 18 weeks after final boost with a higher dosage, IP-10 levels (P = 0.0313) in the Gag/Env group remained higher than baseline. Thus, the influence of vaccine immunogens on mucosal inflammation needs to be considered when developing and evaluating candidate HIV vaccines.

Induction of Both Local Immune Response in Mice and Protection in a Rabbit Model by Intranasal Immunization with Modified Vaccinia Ankara Virus Expressing a Secreted Form of Bovine Herpesvirus 1 Glycoprotein D

In this study, we evaluated the immunogenicity and efficacy of mucosal delivery of a recombinant modified vaccinia Ankara virus (MVA) expressing the secreted version of bovine herpesvirus type 1 (BoHV-1) glycoprotein D (MVA-gDs) without addition of adjuvant in two animal models. First, we demonstrated the capability of MVA-gDs of inducing both local and systemic anti-gD humoral immune response after intranasal immunization of mice. Then, we confirmed that two doses of MVA-gDs administered intranasally to rabbits induced systemic anti-gD antibodies and conferred protection against BoHV-1 challenge. Our results show the potential of using MVA as a vector for the rational design of veterinary vaccines capable of inducing specific and protective immune responses both at local and systemic level.

Sequential Immunization with gp140 Boosts Immune Responses Primed by Modified Vaccinia Ankara or DNA in HIV-Uninfected South African Participants

BACKGROUND

The safety and immunogenicity of SAAVI DNA-C2 (4 mg IM), SAAVI MVA-C (2.9 x 109 pfu IM) and Novartis V2-deleted subtype C gp140 (100 mcg) with MF59 adjuvant in various vaccination regimens was evaluated in HIV-uninfected adults in South Africa.

METHODS

Participants at three South African sites were randomized (1:1:1:1) to one of four vaccine regimens: MVA prime, sequential gp140 protein boost (M/M/P/P); concurrent MVA/gp140 (MP/MP); DNA prime, sequential MVA boost (D/D/M/M); DNA prime, concurrent MVA/gp140 boost (D/D/MP/MP) or placebo. Peak HIV specific humoral and cellular responses were measured.

RESULTS

184 participants were enrolled: 52% were female, all were Black/African, median age was 23 years (range, 18-42 years) and 79% completed all vaccinations. 159 participants reported at least one adverse event, 92.5% were mild or moderate. Five, unrelated, serious adverse events were reported. The M/M/P/P and D/D/MP/MP regimens induced the strongest peak neutralizing and binding antibody responses and the greatest CD4+ T-cell responses to Env. All peak neutralizing and binding antibody responses decayed with time. The MVA, but not DNA, prime contributed to the humoral and cellular immune responses. The D/D/M/M regimen was poorly immunogenic overall but did induce modest CD4+ T-cell responses to Gag and Pol. CD8+ T-cell responses to any antigen were low for all regimens.

CONCLUSIONS

The SAAVI DNA-C2, SAAVI MVA-C and Novartis gp140 with MF59 adjuvant in various combinations were safe and induced neutralizing and binding antibodies and cellular immune responses. Sequential immunization with gp140 boosted immune responses primed by MVA or DNA. The best overall immune responses were seen with the M/M/P/P regimen.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01418235.

Using Plasmids as DNA Vaccines for Infectious Diseases

DNA plasmids can be used to induce a protective (or therapeutic) immune response by delivering genes encoding vaccine antigens. That naked DNA (without the refinement of coat proteins or host evasion systems) can cross from outside the cell into the nucleus and be expressed is particularly remarkable given the sophistication of the immune system in preventing infection by pathogens. As a result of the ease, low cost, and speed of custom gene synthesis, DNA vaccines dangle a tantalizing prospect of the next wave of vaccine technology, promising individual designer vaccines for cancer or mass vaccines with a rapid response time to emerging pandemics. There is considerable enthusiasm for the use of DNA vaccination as an approach, but this enthusiasm should be tempered by the successive failures in clinical trials to induce a potent immune response. The technology is evolving with the development of improved delivery systems that increase expression levels, particularly electroporation and the incorporation of genetically encoded adjuvants. This review will introduce some key concepts in the use of DNA plasmids as vaccines, including how the DNA enters the cell and is expressed, how it induces an immune response, and a summary of clinical trials with DNA vaccines. The review also explores the advances being made in vector design, delivery, formulation, and adjuvants to try to realize the promise of this technology for new vaccines. If the immunogenicity and expression barriers can be cracked, then DNA vaccines may offer a step change in mass vaccination.

The evolution of poxvirus vaccines

After Edward Jenner established human vaccination over 200 years ago, attenuated poxviruses became key players to contain the deadliest virus of its own family: Variola virus (VARV), the causative agent of smallpox. Cowpox virus (CPXV) and horsepox virus (HSPV) were extensively used to this end, passaged in cattle and humans until the appearance of vaccinia virus (VACV), which was used in the final campaigns aimed to eradicate the disease, an endeavor that was accomplished by the World Health Organization (WHO) in 1980. Ever since, naturally evolved strains used for vaccination were introduced into research laboratories where VACV and other poxviruses with improved safety profiles were generated. Recombinant DNA technology along with the DNA genome features of this virus family allowed the generation of vaccines against heterologous diseases, and the specific insertion and deletion of poxvirus genes generated an even broader spectrum of modified viruses with new properties that increase their immunogenicity and safety profile as vaccine vectors. In this review, we highlight the evolution of poxvirus vaccines, from first generation to the current status, pointing out how different vaccines have emerged and approaches that are being followed up in the development of more rational vaccines against a wide range of diseases.

Modified vaccinia virus ankara (MVA) as production platform for vaccines against influenza and other viral respiratory diseases

Respiratory viruses infections caused by influenza viruses, human parainfluenza virus (hPIV), respiratory syncytial virus (RSV) and coronaviruses are an eminent threat for public health. Currently, there are no licensed vaccines available for hPIV, RSV and coronaviruses, and the available seasonal influenza vaccines have considerable limitations. With regard to pandemic preparedness, it is important that procedures are in place to respond rapidly and produce tailor made vaccines against these respiratory viruses on short notice. Moreover, especially for influenza there is great need for the development of a universal vaccine that induces broad protective immunity against influenza viruses of various subtypes. Modified Vaccinia Virus Ankara (MVA) is a replication-deficient viral vector that holds great promise as a vaccine platform. MVA can encode one or more foreign antigens and thus functions as a multivalent vaccine. The vector can be used at biosafety level 1, has intrinsic adjuvant capacities and induces humoral and cellular immune responses. However, there are some practical and regulatory issues that need to be addressed in order to develop MVA-based vaccines on short notice at the verge of a pandemic. In this review, we discuss promising novel influenza virus vaccine targets and the use of MVA for vaccine development against various respiratory viruses.

Broad and potent cellular and humoral immune responses after a second late HIV-modified vaccinia virus ankara vaccination in HIV-DNA-primed and HIV-modified vaccinia virus Ankara-boosted Swedish vaccinees

We have previously shown that an HIV vaccine regimen including three HIV-DNA immunizations and a single HIV-modified vaccinia virus Ankara (MVA) boost was safe and highly immunogenic in Swedish volunteers. A median 38 months after the first HIV-MVA vaccination, 24 volunteers received 10(8) plaque-forming units of HIV-MVA. The vaccine was well tolerated. Two weeks after this HIV-MVA vaccination, 18 (82%) of 22 evaluable vaccinees were interferon (IFN)-γ enzyme-linked immunospot (ELISpot) reactive: 18 to Gag and 10 (45%) to Env. A median minimal epitope count of 4 to Gag or Env was found in a subset of 10 vaccinees. Intracellular cytokine staining revealed CD4(+) and/or CD8(+) T cell responses in 23 (95%) of 24 vaccinees, 19 to Gag and 19 to Env. The frequency of HIV-specific CD4(+) and CD8(+) T cell responses was equally high (75%). A high proportion of CD4(+) and CD8(+) T cell responses to Gag was polyfunctional with production of three or more cytokines (40% and 60%, respectively). Of the Env-specific CD4(+) T cells 40% were polyfunctional. Strong lymphoproliferative responses to Aldrithiol-2 (AT-2)-treated subtype A, B, C, and A_E virus were demonstrable in 21 (95%) of 22 vaccinees. All vaccinees developed binding antibodies to Env and Gag. Neutralizing antibodies were detected in a peripheral blood mononuclear cell (PBMC)-based assay against subtype B and CRF01_AE viruses. The neutralizing antibody response rates were influenced by the vaccine dose and/or mode of delivery used at the previous HIV-MVA vaccination. Thus, a second late HIV-MVA boost induced strong and broad cellular immune responses and improved antibody responses. The data support further exploration of this vaccine concept.

A global approach to HIV-1 vaccine development

A global human immunodeficiency virus-1 (HIV-1) vaccine will have to elicit immune responses capable of providing protection against a tremendous diversity of HIV-1 variants. In this review, we first describe the current state of the HIV-1 vaccine field, outlining the immune responses that are desired in a global HIV-1 vaccine. In particular, we emphasize the likely importance of Env-specific neutralizing and non-neutralizing antibodies for protection against HIV-1 acquisition and the likely importance of effector Gag-specific T lymphocytes for virologic control. We then highlight four strategies for developing a global HIV-1 vaccine. The first approach is to design specific vaccines for each geographic region that include antigens tailor-made to match local circulating HIV-1 strains. The second approach is to design a vaccine that will elicit Env-specific antibodies capable of broadly neutralizing all HIV-1 subtypes. The third approach is to design a vaccine that will elicit cellular immune responses that are focused on highly conserved HIV-1 sequences. The fourth approach is to design a vaccine to elicit highly diverse HIV-1-specific responses. Finally, we emphasize the importance of conducting clinical efficacy trials as the only way to determine which strategies will provide optimal protection against HIV-1 in humans.

Clinical applications of attenuated MVA poxvirus strain

The highly attenuated poxvirus strain modified vaccinia virus Ankara (MVA) has reached maturity as a vector delivery system and as a vaccine candidate against a broad spectrum of diseases. This has been largely recognized from research on virus-host cell interactions and immunological studies in pre-clinical and clinical trials. This review addresses the studies of MVA vectors used in phase I/II clinical trials, with the aim to provide the main findings obtained on their behavior when tested against relevant human diseases and cancer and also highlights the strategies currently implemented to improve the MVA immunogenicity. The authors assess that MVA vectors are progressing as strong vaccine candidates either alone or when administered in combination with other vectors.

Novel directions in HIV-1 vaccines revealed from clinical trials

PURPOSE OF REVIEW

Considerable HIV-1 vaccine development efforts have been deployed over the past decade. Put into perspective, the results from efficacy trials and the identification of correlates of risk have opened large and unforeseen avenues for vaccine development.

RECENT FINDINGS

The Thai efficacy trial, RV144, provided the first evidence that HIV-1 vaccine protection against HIV-1 acquisition could be achieved. The correlate of risk analysis showed that IgG antibodies against the gp120 V2 loop inversely correlated with a decreased risk of infection, whereas Env-specific IgA directly correlated with risk. Further clinical trials will focus on testing new envelope subunit proteins formulated with adjuvants capable of inducing higher and more durable functional antibody responses (both binding and broadly neutralizing antibodies). Moreover, vector-based vaccine regimens that can induce cell-mediated immune responses in addition to humoral responses remain a priority.

SUMMARY

Future efficacy trials will focus on prevention of HIV-1 transmission in heterosexual population in Africa and MSM in Asia. The recent successes leading to novel directions in HIV-1 vaccine development are a result of collaboration and commitment among vaccine manufacturers, funders, scientists and civil society stakeholders. Sustained and broad collaborative efforts are required to advance new vaccine strategies for higher levels of efficacy.

Protection against tuberculosis with homologous or heterologous protein/vector vaccine approaches is not dependent on CD8+ T cells

Considerable effort has been directed to develop Mycobacterium tuberculosis vaccines to boost bacille Calmette-Guérin or for those who cannot be immunized with bacille Calmette-Guérin. We hypothesized that CD4(+) and CD8(+) T cell responses with a heterologous prime/boost vaccine approach could induce long-lived vaccine efficacy against M. tuberculosis in C57BL/6 mice. We produced an adenovirus vector expressing ID93 (Ad5-ID93) for induction of CD8 T cells to use with our candidate tuberculosis vaccine, ID93/glucopyranosyl lipid adjuvant (GLA)-stable emulsion (SE), which induces potent Th1 CD4 T cells. Ad5-ID93 generates ID93-specific CD8(+) T cell responses and induces protection against M. tuberculosis. When Ad5-ID93 is administered in a prime-boost strategy with ID93/GLA-SE, both CD4(+) and CD8(+) T cells are generated and provide protection against M. tuberculosis. In a MHC class I-deficient mouse model, all groups including the Ad5-ID93 group elicited an Ag-specific CD4(+) T cell response and significantly fewer Ag-specific CD8(+) T cells, but were still protected against M. tuberculosis, suggesting that CD4(+) Th1 T cells could compensate for the loss of CD8(+) T cells. Lastly, the order of the heterologous immunizations was critical. Long-lived vaccine protection was observed only when Ad5-ID93 was given as the boost following an ID93/GLA-SE prime. The homologous ID93/GLA-SE prime/boost regimen also induced long-lived protection. One of the correlates of protection between these two approaches was an increase in the total number of ID93-specific IFN-γ-producing CD4(+) T cells 6 mo following the last immunization. Our findings provide insight into the development of vaccines not only for tuberculosis, but other diseases requiring T cell immunity.

Protective efficacy of Modified Vaccinia virus Ankara in preclinical studies

Modified Vaccinia virus Ankara (MVA) is a tissue culture-derived, highly attenuated strain of vaccinia virus (VACV) exhibiting characteristic defective replication in cells from mammalian hosts. In the 1960s MVA was originally generated as a candidate virus for safer vaccination against smallpox. Now, MVA is widely used in experimental vaccine development targeting important infectious diseases and cancer. Versatile technologies for genetic engineering, large-scale production, and quality control facilitate R&D of recombinant and non-recombinant MVA vaccines matching today's requirements for new biomedical products. Such vaccines are attractive candidates for delivering antigens from pathogens against which no, or no effective vaccine is available, including emerging infections caused by highly pathogenic influenza viruses, chikungunya virus, West Nile virus or zoonotic orthopoxviruses. Other directions are seeking valuable vaccines against highly complex diseases such as AIDS, malaria, and tuberculosis. Here, we highlight examples of MVA candidate vaccines against infectious diseases, and review the efforts made to assess both the efficacy of vaccination and immune correlates of protection in preclinical studies.

Safety and immunogenicity of DNA prime and modified vaccinia ankara virus-HIV subtype C vaccine boost in healthy adults

A randomized, double-blind, placebo-controlled phase I trial was conducted in 32 HIV-uninfected healthy volunteers to assess the safety and immunogenicity of 3 doses of DNA vaccine (Advax) plus 1 dose of recombinant modified vaccinia virus Ankara (MVA) (TBC-M4) or 3 doses of TBC-M4 alone (groups A and B, respectively). Both vaccine regimens were found to be safe and well tolerated. Gamma interferon (IFN-γ) enzyme-linked immunosorbent spot (ELISPOT) assay responses were detected in 1/10 (10%) individuals in group A after three Advax primes and in 9/9 individuals (100%) after the MVA boost. In group B, IFN-γ ELISPOT responses were detected in 6/12 (50%) and 7/11 (64%) individuals after the second and third MVA vaccinations, respectively. Responses to all vaccine components, but predominantly to Env, were seen. The breadth and magnitude of the T cell response and viral inhibition were greater in group A than in group B, indicating that the quality of the T-cell response was enhanced by the DNA prime. Intracellular cytokine staining indicated that the T-cell responses were polyfunctional but were skewed toward Env with a CD4(+) phenotype. At 2 weeks after the last vaccination, HIV-specific antibody responses were detected in all (100%) group B and 1/11 (9.1%) group A vaccinees. Vaccinia virus-specific responses were detected in all (100%) group B and 2/11 (18.2%) group A vaccinees. In conclusion, HIV-specific T-cell responses were seen in the majority of volunteers in groups A and B but with a trend toward greater quality of the T-cell response in group A. Antibody responses were better in group B than in group A.

Prospective surveillance for cardiac adverse events in healthy adults receiving modified vaccinia Ankara vaccines: a systematic review

BACKGROUND

Vaccinia-associated myo/pericarditis was observed during the US smallpox vaccination (DryVax) campaign initiated in 2002. A highly-attenuated vaccinia strain, modified vaccinia Ankara (MVA) has been evaluated in clinical trials as a safer alternative to DryVax and as a vector for recombinant vaccines. Due to the lack of prospectively collected cardiac safety data, the US Food and Drug Administration required cardiac screening and surveillance in all clinical trials of MVA since 2004. Here, we report cardiac safety surveillance from 6 phase I trials of MVA vaccines.

METHODS

Four clinical research organizations contributed cardiac safety data using common surveillance methods in trials administering MVA or recombinant MVA vaccines to healthy participants. 'Routine cardiac investigations' (ECGs and cardiac enzymes obtained 2 weeks after injections of MVA or MVA-HIV recombinants, or placebo-controls), and 'Symptom-driven cardiac investigations' are reported. The outcome measure is the number of participants who met the CDC-case definition for vaccinia-related myo/pericarditis or who experienced cardiac adverse events from an MVA vaccine.

RESULTS

Four hundred twenty-five study participants had post-vaccination safety data analyzed, 382 received at least one MVA-containing vaccine and 43 received placebo; 717 routine ECGs and 930 cardiac troponin assays were performed. Forty-five MVA recipients (12%) had additional cardiac testing performed; 22 for cardiac symptoms, 19 for ECG/laboratory changes, and 4 for cardiac symptoms with an ECG/laboratory change. No participant had evidence of symptomatic or asymptomatic myo/pericarditis meeting the CDC-case definition and judged to be related to an MVA vaccine.

CONCLUSIONS

Prospective surveillance of MVA recipients for myo/pericarditis did not detect cardiac adverse reactions in 382 study participants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00082446 NCT003766090 NCT00252148 NCT00083603 NCT00301184 NCT00428337.

Clinical trial in healthy malaria-naïve adults to evaluate the safety, tolerability, immunogenicity and efficacy of MuStDO5, a five-gene, sporozoite/hepatic stage Plasmodium falciparum DNA vaccine combined with escalating dose human GM-CSF DNA

When introduced in the 1990s, immunization with DNA plasmids was considered potentially revolutionary for vaccine development, particularly for vaccines intended to induce protective CD8 T cell responses against multiple antigens. We conducted, in 1997−1998, the first clinical trial in healthy humans of a DNA vaccine, a single plasmid encoding Plasmodium falciparum circumsporozoite protein (PfCSP), as an initial step toward developing a multi-antigen malaria vaccine targeting the liver stages of the parasite. As the next step, we conducted in 2000–2001 a clinical trial of a five-plasmid mixture called MuStDO5 encoding pre-erythrocytic antigens PfCSP, PfSSP2/TRAP, PfEXP1, PfLSA1 and PfLSA3. Thirty-two, malaria-naïve, adult volunteers were enrolled sequentially into four cohorts receiving a mixture of 500 μg of each plasmid plus escalating doses (0, 20, 100 or 500 μg) of a sixth plasmid encoding human granulocyte macrophage-colony stimulating factor (hGM-CSF). Three doses of each formulation were administered intramuscularly by needle-less jet injection at 0, 4 and 8 weeks, and each cohort had controlled human malaria infection administered by five mosquito bites 18 d later. The vaccine was safe and well-tolerated, inducing moderate antigen-specific, MHC-restricted T cell interferon-γ responses but no antibodies. Although no volunteers were protected, T cell responses were boosted post malaria challenge. This trial demonstrated the MuStDO5 DNA and hGM-CSF plasmids to be safe and modestly immunogenic for T cell responses. It also laid the foundation for priming with DNA plasmids and boosting with recombinant viruses, an approach known for nearly 15 y to enhance the immunogenicity and protective efficacy of DNA vaccines.

Poxvirus vectors as HIV/AIDS vaccines in humans

The RV144 phase III clinical trial with the combination of the poxvirus vector ALVAC and the HIV gp120 protein has taught us that a vaccine against HIV/AIDS is possible but further improvements are still needed. Although the HIV protective effect of RV144 was modest (31.2%), these encouraging results reinforce the use of poxvirus vectors as HIV/AIDS vaccine candidates. In this review we focus on the prophylactic clinical studies thus far performed with the more widely studied poxvirus vectors, ALVAC, MVA, NYVAC and fowlpox expressing HIV antigens. We describe the characteristics of each vector administered either alone or in combination with other vectors, with emphasis on the immune parameters evaluated in healthy volunteers, percentage of responders and triggering of humoral and T cell responses. Some of these immunogens induced broad, polyfunctional and long-lasting CD4(+) and CD8(+) T cell responses to HIV-1 antigens in most volunteers, with preference for effector memory T cells, and neutralizing antibodies, immune parameters that might be relevant in protection. Finally, we consider improvements in immunogenicity of the poxvirus vectors by the selective deletion of viral immunomodulatory genes and insertion of host range genes in the poxvirus genome. Overall, the poxvirus vectors have proven to be excellent HIV/AIDS vaccine candidates, with distinct behavior among them, and the future implementation will be dictated by their optimized immune profile in clinical trials.

Full-length HIV-1 immunogens induce greater magnitude and comparable breadth of T lymphocyte responses to conserved HIV-1 regions compared with conserved-region-only HIV-1 immunogens in rhesus monkeys

A global HIV-1 vaccine will likely need to induce immune responses against conserved HIV-1 regions to contend with the profound genetic diversity of HIV-1. Here we evaluated the capacity of immunogens consisting of only highly conserved HIV-1 sequences that are aimed at focusing cellular immune responses on these potentially critical regions. We assessed in rhesus monkeys the breadth and magnitude of T lymphocyte responses elicited by adenovirus vectors expressing either full-length HIV-1 Gag/Pol/Env immunogens or concatenated immunogens consisting of only highly conserved HIV-1 sequences. Surprisingly, we found that the full-length immunogens induced comparable breadth (P = 1.0) and greater magnitude (P = 0.01) of CD8(+) T lymphocyte responses against conserved HIV-1 regions compared with the conserved-region-only immunogens. Moreover, the full-length immunogens induced a 5-fold increased total breadth of HIV-1-specific T lymphocyte responses compared with the conserved-region-only immunogens (P = 0.007). These results suggest that full-length HIV-1 immunogens elicit a substantially increased magnitude and breadth of cellular immune responses compared with conserved-region-only HIV-1 immunogens, including greater magnitude and comparable breadth of responses against conserved sequences.