The link between genetic variation and variability in vaccine responses: Systematic review and meta-analyses

Seasonal influenza vaccines and hurdles to mutual protection

While vaccines against seasonal influenza are available, major hurdles still exist that prevent their use having any impact on epidemic spread. Recent epidemiologic data question the appropriateness of traditional vaccination timing (prior to the winter season) in many parts of the world. Furthermore, vaccine uptake in most countries even in high-risk populations does not reach the 75% target recommended by the World Health Organization. Influenza viruses continually undergo antigenic variation, and both inactivated and live attenuated influenza vaccines confer only short-lived strain-specific immunity, so annual revaccination is required. Improving vaccine-induced immunity is therefore an important goal. A vaccine that could confer durable protection against emerging influenza strains could significantly reduce onward transmission. Therefore, further understanding of protective immunity against influenza (including broadly cross-protective immune mechanisms such as haemagglutinin stem-binding antibodies and T cells) offers the hope of vaccines that can confer the long-lived heterosubtypic immune responses required for mutual protection.

Effect of Tetanus-diphtheria Vaccine on Immune Response to Hepatitis B Vaccine in Low-responder Individuals

Background:

Conventional hepatitis B virus (HBV) vaccination fails to achieve efficient protection in about 5–10% of the world population. Hence, different strategies have been adopted to ameliorate HBV antibody titers. This study aimed to evaluate the concurrent application of tetanus-diphtheria (Td) and HBV vaccination on hepatitis B surface (HBs) antibody titer in low-responder healthy individuals.

Methods:

This was a randomized clinical trial, which was implemented among 140 of medical staff working as health-care workers assumed as low-responders. The subjects were randomly allocated to either control or interventional groups. The control and interventional groups received HBV recombinant vaccine while the latter group was also vaccinated through Td. Enzyme-linked immunosorbent assay was applied to measure HBs antibody (HBsAb) titers just before and 6 months after the last vaccination. All data were entered into SPSS software. Independent t-test, paired t-test, and Chi-square or Fisher's exact test were applied for data comparison.

Results:

Antibody titers of the subjects in the intervention and control groups soared from 49.08 ± 20.08 IU/L to 917.78 ± 204.80 IU/L and from 46.95 ± 18.55 to 586.81 ± 351.77 IU/L, respectively (both P < 0.001); nevertheless, by comparison with control group, variation of antibody titer in the interventional group was significantly higher (P < 0.001).

Conclusions:

Concurrent application of Td and HBV vaccine could effectively enhance protective levels of HBsAb titers in low-responder individuals.

Recent Advances in Application of Pharmacogenomics for Biotherapeutics

Biotherapeutics (BTs), one of the fastest growing classes of drug molecules, offer several advantages over the traditional small molecule pharmaceuticals because of their relatively high specificity, low off-target effects, and biocompatible metabolism, in addition to legal and logistic advantages. However, their clinical utility is limited, among other things, by their high immunogenic potential and/or variable therapeutic efficacy in different patient populations. Both of these issues, also commonly experienced with small molecule drugs, have been addressed effectively in a number of cases by the successful application of pharmacogenomic tools and approaches. In this introductory article of the special issue, we review the current state of application of pharmacogenomics to BTs and offer suggestions for further expansion of the field.

DockTope: a Web-based tool for automated pMHC-I modelling

The immune system is constantly challenged, being required to protect the organism against a wide variety of infectious pathogens and, at the same time, to avoid autoimmune disorders. One of the most important molecules involved in these events is the Major Histocompatibility Complex class I (MHC-I), responsible for binding and presenting small peptides from the intracellular environment to CD8⁺ T cells. The study of peptide:MHC-I (pMHC-I) molecules at a structural level is crucial to understand the molecular mechanisms underlying immunologic responses. Unfortunately, there are few pMHC-I structures in the Protein Data Bank (PDB) (especially considering the total number of complexes that could be formed combining different peptides), and pMHC-I modelling tools are scarce. Here, we present DockTope, a free and reliable web-based tool for pMHC-I modelling, based on crystal structures from the PDB. DockTope is fully automated and allows any researcher to construct a pMHC-I complex in an efficient way. We have reproduced a dataset of 135 non-redundant pMHC-I structures from the PDB (Cα RMSD below 1 Å). Modelling of pMHC-I complexes is remarkably important, contributing to the knowledge of important events such as cross-reactivity, autoimmunity, cancer therapy, transplantation and rational vaccine design.

Human Leukocyte Antigen Diversity: A Southern African Perspective

Despite the increasingly well-documented evidence of high genetic, ethnic, and linguistic diversity amongst African populations, there is limited data on human leukocyte antigen (HLA) diversity in these populations. HLA is part of the host defense mechanism mediated through antigen presentation to effector cells of the immune system. With the high disease burden in southern Africa, HLA diversity data is increasingly important in the design of population-specific vaccines and the improvement of transplantation therapeutic interventions. This review highlights the paucity of HLA diversity data amongst southern African populations and defines a need for information of this kind. This information will support disease association studies, provide guidance in vaccine design, and improve transplantation outcomes.

Vaccines, adjuvants and autoimmunity

Vaccines and autoimmunity are linked fields. Vaccine efficacy is based on whether host immune response against an antigen can elicit a memory T-cell response over time. Although the described side effects thus far have been mostly transient and acute, vaccines are able to elicit the immune system towards an autoimmune reaction. The diagnosis of a definite autoimmune disease and the occurrence of fatal outcome post-vaccination have been less frequently reported. Since vaccines are given to previously healthy hosts, who may have never developed the disease had they not been immunized, adverse events should be carefully accessed and evaluated even if they represent a limited number of occurrences. In this review of the literature, there is evidence of vaccine-induced autoimmunity and adjuvant-induced autoimmunity in both experimental models as well as human patients. Adjuvants and infectious agents may exert their immune-enhancing effects through various functional activities, encompassed by the adjuvant effect. These mechanisms are shared by different conditions triggered by adjuvants leading to the autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome). In conclusion, there are several case reports of autoimmune diseases following vaccines, however, due to the limited number of cases, the different classifications of symptoms and the long latency period of the diseases, every attempt for an epidemiological study has so far failed to deliver a connection. Despite this, efforts to unveil the connection between the triggering of the immune system by adjuvants and the development of autoimmune conditions should be undertaken. Vaccinomics is a field that may bring to light novel customized, personalized treatment approaches in the future.

Utilizing population variation, vaccination, and systems biology to study human immunology

The move toward precision medicine has highlighted the importance of understanding biological variability within and across individuals in the human population. In particular, given the prevalent involvement of the immune system in diverse pathologies, an important question is how much and what information about the state of the immune system is required to enable accurate prediction of future health and response to medical interventions. Towards addressing this question, recent studies using vaccination as a model perturbation and systems-biology approaches are beginning to provide a glimpse of how natural population variation together with multiplexed, high-throughput measurement and computational analysis can be used to uncover predictors of immune response quality in humans. Here I discuss recent developments in this emerging field, with emphasis on baseline correlates of vaccination responses, sources of immune-state variability, as well as relevant features of study design, data generation, and computational analysis.

Systems Biology Approach for Cancer Vaccine Development and Evaluation

Therapeutic cancer vaccines do not hold promise yet as an effective anti-cancer treatment. Lack of efficacy or poor clinical outcomes are due to several antigenic and immunological aspects that need to be addressed in order to reverse such trends and significantly improve cancer vaccines’ efficacy. The newly developed high throughput technologies and computational tools are instrumental to this aim allowing the identification of more specific antigens and the comprehensive analysis of the innate and adaptive immunities. Here, we review the potentiality of systems biology in providing novel insights in the mechanisms of the action of vaccines to improve their design and effectiveness.

Antibody and T-cell responses associated with experimental human malaria infection or vaccination show limited relationships

This study examined specific antibody and T-cell responses associated with experimental malaria infection or malaria vaccination, in malaria-naive human volunteers within phase I/IIa vaccine trials, with a view to investigating inter-relationships between these types of response. Malaria infection was via five bites of Plasmodium falciparum-infected mosquitoes, with individuals reaching patent infection by 11-12 days, having harboured four or five blood-stage cycles before drug clearance. Infection elicited a robust antibody response against merozoite surface protein-119 , correlating with parasite load. Classical class switching was seen from an early IgM to an IgG1-dominant response of increasing affinity. Malaria-specific T-cell responses were detected in the form of interferon-γ and interleukin-4 (IL-4) ELIspot, but their magnitude did not correlate with the magnitude of antibody or its avidity, or with parasite load. Different individuals who were immunized with a virosome vaccine comprising influenza antigens combined with P. falciparum antigens, demonstrated pre-existing interferon-γ, IL-2 and IL-5 ELIspot responses against the influenza antigens, and showed boosting of anti-influenza T-cell responses only for IL-5. The large IgG1-dominated anti-parasite responses showed limited correlation with T-cell responses for magnitude or avidity, both parameters being only negatively correlated for IL-5 secretion versus anti-apical membrane antigen-1 antibody titres. Overall, these findings suggest that cognate T-cell responses across a range of magnitudes contribute towards driving potentially effective antibody responses in infection-induced and vaccine-induced immunity against malaria, and their existence during immunization is beneficial, but magnitudes are mostly not inter-related.

The role of Toll-like receptor 4 polymorphisms in vaccine immune response

Toll-like receptors (TLRs) are a class of pattern recognition receptors that are deputed to recognise a range of molecular structures in pathogens. One of the most studied members of this family is the TLR4, which is essential for the signalling of lipopolysaccharide. The gene encoding for TLR4 is highly polymorphic and this genetic variability may explain in part the interindividual variability observed in several clinical setting, including the response to vaccination. Herein, we review and systematise the available scientific evidence about the effect of TLR4 polymorphisms on vaccine response, including approved prophylactic, new therapeutic cancer vaccines and recently approved vaccine adjuvants. Data reviewed in this analysis indicate that TLR4 polymorphisms significantly affect vaccine response. If these results are confirmed by further analyses, the use of these genetic biomarkers may become a useful tool to tailor vaccination in specific subsets of patients.

Post-vaccination Immunity Against Hepatitis B Virus and Predictors for Non-responders Among Medical Staff

BACKGROUND

Hepatitis B virus (HBV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). HB vaccination is an essential step in the prevention of the disease and its consequent complications.

OBJECTIVES

Immune status of medical personnel in teaching hospitals of Khuzestan is not well known. Since these personnel are usually at risk of needle stick and other high-risk events, some challenges exist in infection control committee with regard to managing these events. This study was conducted to assess post-vaccination immunity status and non-response to HBV vaccine as well as its predictors among medical staff in a teaching hospital affiliated to Ahvaz Jundishapur University of Medical Sciences (AJUMS) in Ahvaz, southwest Iran.

PATIENTS AND METHODS

In this retrospective cross-sectional study, the medical staff of a teaching hospital was evaluated for their immune response against HBV and factors affecting it. The study conducted in Razi Hospital, Ahvaz City, southwest of Iran, in 2013. Demographical, clinical, and laboratory data registered in medical files of hospital staff were analyzed by SPSS software version 16 using chi-square and Fisher exact tests. Differences with P value < 0.05 were considered significant. To identify predictors for non-responders, we used odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Out of 239 participants, 43 (18 %) were men and 196 (82%) were women. Their mean age was 31.9 ± 18.1 years (range of 20 - 55 years). Fourteen (5.9%) participants were non-responders, 37 (15.5%) were poor responders, and 188 (78.6%) were good responders. The non-responders were older (> 50 years) than the responders (P = 0.0001), while the body mass index (BMI) was not significantly different (P = 0.37) between them. Diabetes mellitus (DM) (OR: 7.3, 95% CI, 1.3 - 41.7, P = 0.05), and using immunosuppressive drugs (ISD) (OR: 3.2, 95% CI, 1.1 - 11.5, P = 0.03) were two variables in association with non-response to HB vaccine.

CONCLUSIONS

Non-response rate to HB vaccine in our study was approximately 6%. Age over 50 years, DM, and receiving immunosuppressive drugs may be considered as predictors for non-response to HB vaccine in medical staff.

The genetic regulation of infant immune responses to vaccination

A number of factors are recognized to influence immune responses to vaccinations including age, gender, the dose, and quality of the antigen used, the number of doses given, the route of administration, and the nutritional status of the recipient. Additionally, several immunogenetic studies have identified associations between polymorphisms in genes encoding immune response proteins, both innate and adaptive, and variation in responses to vaccines. Variants in the genes encoding Toll-like receptors, HLA molecules, cytokines, and cytokine receptors have associated with heterogeneity of responses to a wide range of vaccines including measles, hepatitis B, influenza A, BCG, Haemophilus influenzae type b, and certain Neisseria meningitidis serotypes, amongst others. However, the vast majority of these studies have been conducted in older children and adults and there are very few data available from studies conducted in infants. This paper reviews the evidence to date that host genes influencing vaccines responses in these older population and identifies a large gap in our understanding of the genetic regulation of responses in early life. Given the high mortality from infection in early life and the challenges of developing vaccines that generate effective immune responses in the context of the developing immune system further research on infant populations is required.

Single-nucleotide polymorphism associations in common with immune responses to measles and rubella vaccines

Single-nucleotide polymorphisms (SNPs) in candidate immune response genes were evaluated for associations with measles- and rubella-specific neutralizing antibodies, interferon (IFN)-γ, and interleukin (IL)-6 secretion in two separate association analyses in a cohort of healthy immunized subjects. We identified six SNP associations shared between the measles-specific and rubella-specific immune responses, specifically neutralizing antibody titers (DDX58), secreted IL-6 (IL10RB, IL12B), and secreted IFN-γ (IFNAR2, TLR4). An intronic SNP (rs669260) in the antiviral innate immune receptor gene, DDX58, was significantly associated with increased neutralizing antibody titers for both measles and rubella viral antigens post-MMR vaccination (p values 0.02 and 0.0002, respectively). Significant associations were also found between IL10RB (rs2284552; measles study p value 0.006, rubella study p value 0.00008) and IL12B (rs2546893; measles study p value 0.005, rubella study p value 0.03) gene polymorphisms and variations in both measles- and rubella virus-specific IL-6 responses. We also identified associations between individual SNPs in the IFNAR2 and TLR4 genes that were associated with IFN-γ secretion for both measles and rubella vaccine-specific immune responses. These results are the first to indicate that there are SNP associations in common across measles and rubella vaccine immune responses and that SNPs from multiple genes involved in innate and adaptive immune response regulation may contribute to the overall human antiviral response.

Association of HLA alleles with the responsiveness to hepatitis B virus vaccination in Korean infants

Hepatitis B virus (HBV) vaccination is the most effective means of countering HBV-related morbidity and mortality, and individuals who do not respond to vaccination (non-responders) are problematic. The aim of the present study was to investigate associations between HLA and responsiveness to HBV vaccine in Korean infants. A total of 944 healthy Korean infants 9-12 months old were enrolled, and HLA distribution was compared among subgroups in accordance with the response to HBV vaccination. The HLA distribution of the subjects was similar to known Korean population data and did not deviate from the HWE proportions. The alleles that showed positive associations with non-responsiveness (<10mIU/mL) or low antibody titer (<100mIU/mL) were HLA-A*33, B62, DRB1*04, and DRB1*07, while the alleles A*02 and DRB1*08 showed negative associations. Among these alleles, B62, DRB1*07 and DRB1*08(-) showed significant associations with a poor or decreased response to vaccination even after correction (OR=1.83, 1.99, 5.63; pc<0.05) and also showed dose effects. After stratification by other associated alleles at different loci, B62 and DRB1*07 were independently associated with non-responsiveness, but A*02(-) and DRB1*08(-) lost their individual associations. The combined association of A*02(-)-DRB1*08(-) and B62-DRB1*08(-) was significant (OR=25.2 and 24.5; pc<0.05). Although the hierarchy is not clear, we can assume the following: (i) B62 and DRB1*07 have independent effects, (ii) DRB1*08(-) has a very strong and synergic effect, and (iii) there is probability of a third factor controlling A*02(-) and DRB1*08(-) with an effect on non-responsiveness to HBV vaccination in Korean infants.