Vaccines

14 pages, 583 KiB

Open AccessEditor’s ChoiceReview

Long-Term Effects of Human Papillomavirus Vaccination in Clinical Trials and Real-World Data: A Systematic Review

by Megumi Kurosawa, Masayuki Sekine, Manako Yamaguchi, Risa Kudo, Sharon J. B. Hanley, Megumi Hara, Sosuke Adachi, Yutaka Ueda, Etsuko Miyagi, Sayaka Ikeda, Asami Yagi and Takayuki Enomoto

Vaccines 2022, 10(2), 256; https://doi.org/10.3390/vaccines10020256 - 8 Feb 2022

Cited by 7 | Viewed by 7603

Abstract

The preventive effect of HPV vaccines against anogenital and oropharyngeal cancers has been proven in both clinical trials and real-world data. We reviewed the published evidence about the long-term efficacy and effectiveness of the HPV vaccine in available papers of clinical trials and [...] Read more.

The preventive effect of HPV vaccines against anogenital and oropharyngeal cancers has been proven in both clinical trials and real-world data. We reviewed the published evidence about the long-term efficacy and effectiveness of the HPV vaccine in available papers of clinical trials and real-world data. As far as we searched, the longest period of preventive effect for the bivalent, 4-valent, and 9-valent vaccine were 11 years in the Costa Rica trial, 14 years in the FUTURE II, and 8 years in the LTFU extension study of V503-002 and the Scandinavian study, respectively. The sustained clinical effect during the observation period was longest for the 4-valent vaccine. In real-world data, the longest observation period of the vaccine effectiveness was 12 years in an Australian study for the 4-valent vaccine. On the other hand, the longest period of long-term persistence of HPV vaccine-induced seropositivity was 14 years in FUTURE II for the 4-valent vaccine. For the bivalent vaccine, additional long-term follow-up studies may not have been planned due to the launch of the 4-valent and 9-valent vaccines. In some studies of the 9-valent vaccine, the results have not yet been published because of the short observation period. The additional results are expected in the future. In a national immunization program, most girls and boys are inoculated with HPV vaccine by the time puberty begins; thus, it is important to monitor the vaccine effect at least until the sexually active period in their 20s and 30s. Full article

(This article belongs to the Special Issue Epidemiological Studies of HPV Infection and Vaccination)

► Show Figures

Figure 1

13 pages, 275 KiB

Open AccessEditor’s ChoiceArticle

Tipping the Fencesitters—The Impact of a Minimal Intervention Enhanced with Biological Facts on Swiss Student Teachers’ Perception of HPV Vaccination Safety

by Alla Keselman and Albert Zeyer

Vaccines 2022, 10(2), 175; https://doi.org/10.3390/vaccines10020175 - 23 Jan 2022

Cited by 6 | Viewed by 3244

Abstract

Not much is known about the role of scientific knowledge in vaccination decision making. This study is based on previous findings that the concern about the human papillomavirus (HPV) agent mutating back to a virulent HPV was common among Swiss student teachers and [...] Read more.

Not much is known about the role of scientific knowledge in vaccination decision making. This study is based on previous findings that the concern about the human papillomavirus (HPV) agent mutating back to a virulent HPV was common among Swiss student teachers and turned out to be one factor of vaccine hesitancy. The study investigate the impact of a standard public health brochure describing the effectiveness, safety, and importance of HPV vaccination on young student teachers, and the additional effect of supplementing the standard brochure with biological arguments against the mutation concerns. It uses a pre-posttest design and assigns participants randomly to two groups, one reviewing a standard public health brochure, the other the same brochure enhanced with additional biological information. Participants in both groups showed a significant positive change in their beliefs about vaccination safety, effectiveness, and importance in preventing cervical cancer. Post hoc analysis showed significant safety beliefs gain for the subgroup of participants who received the biology-enhanced text and held moderate, rather than high or low, pretest safety beliefs—the so-called fencesitters. We conclude that these fencesitters may particularly profit from even minimal (biologically supplemented) interventions, an effect that should receive more attention in future research. Full article

(This article belongs to the Special Issue Vaccine Hesitancy and Child Immunizations: Rationales, Issues and Knowledge Gaps 2.0)

10 pages, 1499 KiB

Open AccessEditor’s ChoiceArticle

Reduced Titers of Circulating Anti-SARS-CoV-2 Antibodies and Risk of COVID-19 Infection in Healthcare Workers during the Nine Months after Immunization with the BNT162b2 mRNA Vaccine

by Luca Coppeta, Cristiana Ferrari, Giuseppina Somma, Andrea Mazza, Umberto D’Ancona, Fabbio Marcuccilli, Sandro Grelli, Marco Trabucco Aurilio, Antonio Pietroiusti, Andrea Magrini and Stefano Rizza

Vaccines 2022, 10(2), 141; https://doi.org/10.3390/vaccines10020141 - 18 Jan 2022

Cited by 35 | Viewed by 3648

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has had a tremendous impact on health services; hundreds of thousands of healthcare workers (HCWs) have died from coronavirus disease 2019 (COVID-19). The introduction of the BNT162b2 mRNA vaccine in Italy provided recipients with [...] Read more.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has had a tremendous impact on health services; hundreds of thousands of healthcare workers (HCWs) have died from coronavirus disease 2019 (COVID-19). The introduction of the BNT162b2 mRNA vaccine in Italy provided recipients with significant protection against COVID-19 within one to two weeks after the administration of the second of the two recommended doses. While the vaccine induces a robust T cell response, the protective role of factors and pathways other than those related to memory B cell responses to specific SARS-CoV-2 antigens remains unclear. This retrospective study aimed to evaluate the determinants of serological protection in a group of vaccinated HCWs (n = 793) by evaluating circulating levels of antiviral spike receptor-binding domain (S-RBD) antibodies during the nine-month period following vaccination. We found that 99.5% of the HCWs who received the two doses of the BNT162b2 vaccine developed protective antibodies that were maintained at detectable levels for as long as 250 days after the second dose of the vaccine. Multivariate analysis was performed on anti-S-RBD titers in a subgroup of participants (n = 173) that were evaluated twice during this period. The results of this analysis reveal that the antibody titer observed at the second time point was significantly related to the magnitude of the primary response, the time that had elapsed between the first and the second evaluation, and a previous history of SARS-CoV-2 infection. Of importance is the finding that despite waning antibody titers following vaccination, none of the study participants contracted severe COVID-19 during the observational period. Full article

(This article belongs to the Special Issue Feature Papers of Epidemiology and Vaccines)

► Show Figures

Figure 1

9 pages, 209 KiB

Open AccessEditor’s ChoiceReview

Covid-19-Associated Pulmonary Aspergillosis: The Other Side of the Coin

by Claudio Costantini, Frank L. van de Veerdonk and Luigina Romani

Vaccines 2020, 8(4), 713; https://doi.org/10.3390/vaccines8040713 - 1 Dec 2020

Cited by 25 | Viewed by 4356

Abstract

The immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a critical factor in the clinical presentation of COVID-19, which may range from asymptomatic to a fatal, multi-organ disease. A dysregulated immune response not only compromises the ability of the host [...] Read more.

The immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a critical factor in the clinical presentation of COVID-19, which may range from asymptomatic to a fatal, multi-organ disease. A dysregulated immune response not only compromises the ability of the host to resolve the viral infection, but may also predispose the individual to secondary bacterial and fungal infections, a risk to which the current therapeutic immunomodulatory approaches significantly contribute. Among the secondary infections that may occur in COVID-19 patients, coronavirus-associated pulmonary aspergillosis (CAPA) is emerging as a potential cause of morbidity and mortality, although many aspects of the disease still remain unresolved. With this opinion, we present the current view of CAPA and discuss how the same mechanisms that underlie the dysregulated immune response in COVID-19 increase susceptibility to Aspergillus infection. Likewise, resorting to endogenous pathways of immunomodulation may not only restore immune homeostasis in COVID-19 patients, but also reduce the risk for aspergillosis. Therefore, CAPA represents the other side of the coin in COVID-19 and our advances in the understanding and treatment of the immune response in COVID-19 should represent the framework for the study of CAPA. Full article

(This article belongs to the Special Issue Our Immune System Is the First Line of Defense towards Infections: Modulation of the Immune System to Boost the Host Defense Response towards Pathogens)

14 pages, 1756 KiB

Open AccessEditor’s ChoiceArticle

Influences on Attitudes Regarding Potential COVID-19 Vaccination in the United States

by Kendall Pogue, Jamie L. Jensen, Carter K. Stancil, Daniel G. Ferguson, Savannah J. Hughes, Emily J. Mello, Ryan Burgess, Bradford K. Berges, Abraham Quaye and Brian D. Poole

Vaccines 2020, 8(4), 582; https://doi.org/10.3390/vaccines8040582 - 3 Oct 2020

Cited by 369 | Viewed by 29719

Abstract

The COVID-19 pandemic continues to ravage the world, with the United States being highly affected. A vaccine provides the best hope for a permanent solution to controlling the pandemic. However, to be effective, a vaccine must be accepted and used by a large [...] Read more.

The COVID-19 pandemic continues to ravage the world, with the United States being highly affected. A vaccine provides the best hope for a permanent solution to controlling the pandemic. However, to be effective, a vaccine must be accepted and used by a large majority of the population. The aim of this study was to understand the attitudes towards and obstacles facing vaccination with a potential COVID-19 vaccine. To measure these attitudes a survey was administered to 316 respondents across the United States by a survey corporation. Structural equation modeling was used to analyze the relationships of several factors with attitudes toward potential COVID-19 vaccination. Prior vaccine usage and attitudes predicted attitudes towards COVID-19 vaccination. Assessment of the severity of COVID-19 for the United States was also predictive. Approximately 68% of all respondents were supportive of being vaccinated for COVID-19, but side effects, efficacy and length of testing remained concerns. Longer testing, increased efficacy and development in the United States were significantly associated with increased vaccine acceptance. Messages promoting COVID-19 vaccination should seek to alleviate the concerns of those who are already vaccine-hesitant. Messaging directed at the benefits of vaccination for the United States as a country would address the second predictive factor. Enough time should be taken to allay concerns about both short- and long-term side effects before a vaccine is released. Full article

(This article belongs to the Special Issue Vaccination and Public Health: Optimizing Vaccine Uptake through the Application of Social and Behavioral Science Theory, Principles, and Strategies)

► Show Figures

Figure 1

11 pages, 523 KiB

Open AccessEditor’s ChoiceArticle

Relationship between Citizens’ Health Engagement and Intention to Take the COVID-19 Vaccine in Italy: A Mediation Analysis

by Guendalina Graffigna, Lorenzo Palamenghi, Stefania Boccia and Serena Barello

Vaccines 2020, 8(4), 576; https://doi.org/10.3390/vaccines8040576 - 1 Oct 2020

Cited by 136 | Viewed by 10016

Abstract

The actual effectiveness of the still-to-come vaccination against the coronavirus SARS-CoV-2 might be challenged by vaccine hesitancy, a rather common and known phenomenon whose psychological predictors are, nevertheless, still largely debated. Our study aims at understanding how adult citizens’ health engagement, perceived COVID-19 [...] Read more.

The actual effectiveness of the still-to-come vaccination against the coronavirus SARS-CoV-2 might be challenged by vaccine hesitancy, a rather common and known phenomenon whose psychological predictors are, nevertheless, still largely debated. Our study aims at understanding how adult citizens’ health engagement, perceived COVID-19 susceptibility and severity, and general vaccine-related attitudes affect the willingness to vaccinate against COVID-19. To that end, on a sample of Italian citizens, we implemented a path model to test the impact of health engagement on the willingness to vaccinate against SARS-CoV-2, and whether this relationship is direct or mediated by the general attitude towards vaccines and the risk perception. Moreover, we tested the configural and weak invariance of the model across gender and three age groups. Results show that health engagement is positively related to the intention to vaccinate and that this relationship is partially mediated by the general attitude towards vaccines. The model appears invariant across genders and partially invariant across age groups, showing some differences in the role of perceived susceptibility. These findings vouch for the implementation of educational campaigns aimed at sustaining future vaccination programs that also include health engagement promotion. Full article

(This article belongs to the Special Issue Vaccine Hesitancy and Child Immunizations: Rationales, Issues and Knowledge Gaps)

► Show Figures

Figure 1

14 pages, 864 KiB

Open AccessEditor’s ChoiceArticle

Acceptance of COVID-19 Vaccination during the COVID-19 Pandemic in China

by Jiahao Wang, Rize Jing, Xiaozhen Lai, Haijun Zhang, Yun Lyu, Maria Deloria Knoll and Hai Fang

Vaccines 2020, 8(3), 482; https://doi.org/10.3390/vaccines8030482 - 27 Aug 2020

Cited by 669 | Viewed by 50227

Abstract

Background: Faced with the coronavirus disease 2019 (COVID-19) pandemic, the development of COVID-19 vaccines has been progressing at an unprecedented rate. This study aimed to evaluate the acceptance of COVID-19 vaccination in China and give suggestions for vaccination strategies and immunization programs accordingly. [...] Read more.

Background: Faced with the coronavirus disease 2019 (COVID-19) pandemic, the development of COVID-19 vaccines has been progressing at an unprecedented rate. This study aimed to evaluate the acceptance of COVID-19 vaccination in China and give suggestions for vaccination strategies and immunization programs accordingly. Methods: In March 2020, an anonymous cross-sectional survey was conducted online among Chinese adults. The questionnaire collected socio-demographic characteristics, risk perception, the impact of COVID-19, attitudes, acceptance and attribute preferences of vaccines against COVID-19 during the pandemic. Multivariate logistic regression was performed to identify the influencing factors of vaccination acceptance. Results: Of the 2058 participants surveyed, 1879 (91.3%) stated that they would accept COVID-19 vaccination after the vaccine becomes available, among whom 980 (52.2%) wanted to get vaccinated as soon as possible, while others (47.8%) would delay the vaccination until the vaccine’s safety was confirmed. Participants preferred a routine immunization schedule (49.4%) to emergency vaccination (9.0%) or either of them (41.6%). Logistic regression showed that being male, being married, perceiving a high risk of infection, being vaccinated against influenza in the past season, believing in the efficacy of COVID-19 vaccination or valuing doctor’s recommendations could increase the probability of accepting COVID-19 vaccination as soon as possible, while having confirmed or suspected cases in local areas, valuing vaccination convenience or vaccine price in decision-making could hinder participants from immediate vaccination. Conclusion: During the pandemic period, a strong demand for and high acceptance of COVID-19 vaccination has been shown among the Chinese population, while concerns about vaccine safety may hinder the promotion of vaccine uptake. To expand vaccination coverage, immunization programs should be designed to remove barriers in terms of vaccine price and vaccination convenience, and health education and communication from authoritative sources are important ways to alleviate public concerns about vaccine safety. Full article

(This article belongs to the Special Issue Vaccination and Public Health: Optimizing Vaccine Uptake through the Application of Social and Behavioral Science Theory, Principles, and Strategies)

► Show Figures

Figure 1

10 pages, 1596 KiB

Open AccessEditor’s ChoiceCommunication

Tetravalent Immunogen Assembled from Conserved Regions of HIV-1 and Delivered as mRNA Demonstrates Potent Preclinical T-Cell Immunogenicity and Breadth

by Nathifa Moyo, Edmund G. Wee, Bette Korber, Kapil Bahl, Samantha Falcone, Sunny Himansu, Adrianne L. Wong, Antu K. Dey, Mark Feinberg and Tomáš Hanke

Vaccines 2020, 8(3), 360; https://doi.org/10.3390/vaccines8030360 - 6 Jul 2020

Cited by 16 | Viewed by 10576

Abstract

A vaccine will likely be one of the key tools for ending the HIV-1/AIDS epidemic by preventing HIV-1 spread within uninfected populations and achieving a cure for people living with HIV-1. The currently prevailing view of the vaccine field is to introduce protective [...] Read more.

A vaccine will likely be one of the key tools for ending the HIV-1/AIDS epidemic by preventing HIV-1 spread within uninfected populations and achieving a cure for people living with HIV-1. The currently prevailing view of the vaccine field is to introduce protective antibodies, nevertheless, a vaccine to be effective may need to harness protective T cells. We postulated that focusing a T-cell response on the most vulnerable regions of the HIV-1 proteome while maximizing a perfect match between the vaccine and circulating viruses will control HIV-1 replication. We currently use a combination of replication-deficient simian (chimpanzee) adenovirus and poxvirus modified vaccinia virus Ankara to deliver bivalent conserved-mosaic immunogens to human volunteers. Here, we exploit the mRNA platform by designing tetravalent immunogens designated as HIVconsvM, and demonstrate that mRNA formulated in lipid nanoparticles induces potent, broad and polyfunctional T-cell responses in a pre-clinical model. These results support optimization and further development of this vaccine strategy in experimental medicine trials in humans. Full article

(This article belongs to the Section HIV Vaccines)

► Show Figures

Figure 1

13 pages, 2636 KiB

Open AccessEditor’s ChoiceArticle

Yeast-Based Aβ1-15 Vaccine Elicits Strong Immunogenicity and Attenuates Neuropathology and Cognitive Deficits in Alzheimer’s Disease Transgenic Mice

by Dong-qun Liu, Shuai Lu, Lun Zhang, Ya-ru Huang, Mei Ji, Xiao-ying Sun, Xiao-ge Liu and Rui-tian Liu

Vaccines 2020, 8(3), 351; https://doi.org/10.3390/vaccines8030351 - 1 Jul 2020

Cited by 10 | Viewed by 4228

Abstract

Immunotherapy focusing on reducing the amyloid-beta (Aβ) burden is a promising treatment strategy for Alzheimer’s disease (AD). Many clinical studies on AD immunotherapies have failed due to low safety and efficacy, calling for a highly potent AD vaccine which induces sufficient antibody titer [...] Read more.

Immunotherapy focusing on reducing the amyloid-beta (Aβ) burden is a promising treatment strategy for Alzheimer’s disease (AD). Many clinical studies on AD immunotherapies have failed due to low safety and efficacy, calling for a highly potent AD vaccine which induces sufficient antibody titer while avoiding side effects. Here, we designed a yeast-based vaccine Y-5A15 comprising five copies of Aβ1-15 displayed on the surface of yeast cell wall, and we subcutaneously immunized APP/PS1 mice three times. Our results demonstrated that the Y-5A15 remarkably enhanced the Aβ epitope immunogenicity and elicited high antibody titers against Aβ in AD mice. Importantly, Y-5A15 vaccination successfully reduced Aβ levels, plaque burden and glial activation, rescued synaptic deficits and significantly ameliorated memory and cognitive decline in APP/PS1 transgenic mice, suggesting that the yeast-based Aβ epitope vaccine has a promising potency for the treatment of AD. Full article

(This article belongs to the Special Issue Human Leukocyte Antigen (HLA) and Vaccines)

► Show Figures

Figure 1

15 pages, 2692 KiB

Open AccessEditor’s ChoiceArticle

Remodeling of the Histoplasma Capsulatum Membrane Induced by Monoclonal Antibodies

by Meagan C. Burnet, Daniel Zamith-Miranda, Heino M. Heyman, Karl K. Weitz, Erin L. Bredeweg, Joshua D. Nosanchuk and Ernesto S. Nakayasu

Vaccines 2020, 8(2), 269; https://doi.org/10.3390/vaccines8020269 - 2 Jun 2020

Cited by 9 | Viewed by 4297

Abstract

Antibodies play a central role in host immunity by directly inactivating or recognizing an invading pathogen to enhance different immune responses to combat the invader. However, the cellular responses of pathogens to the presence of antibodies are not well-characterized. Here, we used different [...] Read more.

Antibodies play a central role in host immunity by directly inactivating or recognizing an invading pathogen to enhance different immune responses to combat the invader. However, the cellular responses of pathogens to the presence of antibodies are not well-characterized. Here, we used different mass spectrometry techniques to study the cellular responses of the pathogenic fungus Histoplasma capsulatum to monoclonal antibodies (mAb) against HSP60, the surface protein involved in infection. A proteomic analysis of H. capsulatum yeast cells revealed that mAb binding regulates a variety of metabolic and signaling pathways, including fatty acid metabolism, sterol metabolism, MAPK signaling and ubiquitin-mediated proteolysis. The regulation of the fatty acid metabolism was accompanied by increases in the level of polyunsaturated fatty acids, which further augmented the degree of unsaturated lipids in H. capsulatum’s membranes and energy storage lipids, such as triacylglycerols, phosphatidylcholines, phosphatidylethanolamines and phosphatidylinositols. MAb treatment also regulated sterol metabolism by increasing the levels of cholesterol and ergosterol in the cells. We also showed that global changes in the lipid profiles resulted in an increased susceptibility of H. capsulatum to the ergosterol-targeting drug amphotericin B. Overall, our data showed that mAb induction of global changes in the composition of H. capsulatum membranes can potentially impact antifungal treatment during histoplasmosis. Full article

(This article belongs to the Section Pathogens-host Immune Interface)

► Show Figures

Figure 1

20 pages, 16511 KiB

Open AccessEditor’s ChoiceArticle

Vaccination Against Amyloidogenic Aggregates in Pancreatic Islets Prevents Development of Type 2 Diabetes Mellitus

by Elisa S. Roesti, Christina N. Boyle, Daniel T. Zeman, Marcos Sande-Melon, Federico Storni, Gustavo Cabral-Miranda, Alexander Knuth, Thomas A. Lutz, Monique Vogel and Martin F. Bachmann

Vaccines 2020, 8(1), 116; https://doi.org/10.3390/vaccines8010116 - 2 Mar 2020

Cited by 19 | Viewed by 6183

Abstract

Type 2 diabetes mellitus (T2DM) is a chronic progressive disease characterized by insulin resistance and insufficient insulin secretion to maintain normoglycemia. The majority of T2DM patients bear amyloid deposits mainly composed of islet amyloid polypeptide (IAPP) in their pancreatic islets. These—originally β-cell secretory [...] Read more.

Type 2 diabetes mellitus (T2DM) is a chronic progressive disease characterized by insulin resistance and insufficient insulin secretion to maintain normoglycemia. The majority of T2DM patients bear amyloid deposits mainly composed of islet amyloid polypeptide (IAPP) in their pancreatic islets. These—originally β-cell secretory products—extracellular aggregates are cytotoxic for insulin-producing β-cells and are associated with β-cell loss and inflammation in T2DM advanced stages. Due to the absence of T2DM preventive medicaments and the presence of only symptomatic drugs acting towards increasing hormone secretion and action, we aimed at establishing a novel disease-modifying therapy targeting the cytotoxic IAPP deposits in order to prevent the development of T2DM. We generated a vaccine based on virus-like particles (VLPs), devoid of genomic material, coupled to IAPP peptides inducing specific antibodies against aggregated, but not monomeric IAPP. Using a mouse model of islet amyloidosis, we demonstrate in vivo that our vaccine induced a potent antibody response against aggregated, but not soluble IAPP, strikingly preventing IAPP depositions, delaying onset of hyperglycemia and the induction of the associated pro-inflammatory cytokine Interleukin 1β (IL-1β). We offer the first cost-effective and safe disease-modifying approach targeting islet dysfunction in T2DM, preventing pathogenic aggregates without disturbing physiological IAPP function. Full article

(This article belongs to the Special Issue Genomic Medicine and Advances in Vaccine Technology and Development in the Developing and Developed World)

► Show Figures

Figure 1

33 pages, 3568 KiB

Open AccessEditor’s ChoiceReview

Anti-Leishmanial Vaccines: Assumptions, Approaches, and Annulments

by Shubhranshu Zutshi, Sunil Kumar, Prashant Chauhan, Yashwant Bansode, Arathi Nair, Somenath Roy, Arup Sarkar and Bhaskar Saha

Vaccines 2019, 7(4), 156; https://doi.org/10.3390/vaccines7040156 - 18 Oct 2019

Cited by 30 | Viewed by 6851

Abstract

Leishmaniasis is a neglected protozoan parasitic disease that occurs in 88 countries but a vaccine is unavailable. Vaccination with live, killed, attenuated (physically or genetically) Leishmania have met with limited success, while peptide-, protein-, or DNA-based vaccines showed promise only in animal models. [...] Read more.

Leishmaniasis is a neglected protozoan parasitic disease that occurs in 88 countries but a vaccine is unavailable. Vaccination with live, killed, attenuated (physically or genetically) Leishmania have met with limited success, while peptide-, protein-, or DNA-based vaccines showed promise only in animal models. Here, we critically assess several technical issues in vaccination and expectation of a host-protective immune response. Several studies showed that antigen presentation during priming and triggering of the same cells in infected condition are not comparable. Altered proteolytic processing, antigen presentation, protease-susceptible sites, and intracellular expression of pathogenic proteins during Leishmania infection may vary dominant epitope selection, MHC-II/peptide affinity, and may deter the reactivation of desired antigen-specific T cells generated during priming. The robustness of the memory T cells and their functions remains a concern. Presentation of the antigens by Leishmania-infected macrophages to antigen-specific memory T cells may lead to change in the T cells’ functional phenotype or anergy or apoptosis. Although cells may be activated, the peptides generated during infection may be different and cross-reactive to the priming peptides. Such altered peptide ligands may lead to suppression of otherwise active antigen-specific T cells. We critically assess these different immunological issues that led to the non-availability of a vaccine for human use. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI