Heterologous Infection Research Articles

BCG vaccination in humans inhibits systemic inflammation in a sex-dependent manner.

BACKGROUNDInduction of innate immune memory, also termed trained immunity, by the antituberculosis vaccine bacillus Calmette-Guérin (BCG) contributes to protection against heterologous infections. However, the overall impact of BCG vaccination on the inflammatory status of an individual is not known; while induction of trained immunity may suggest increased inflammation, BCG vaccination has been epidemiologically associated with a reduced incidence of inflammatory and allergic diseases.METHODSWe investigated the impact of BCG (BCG-Bulgaria, InterVax) vaccination on systemic inflammation in a cohort of 303 healthy volunteers, as well as the effect of the inflammatory status on the response to vaccination. A targeted proteome platform was used to measure circulating inflammatory proteins before and after BCG vaccination, while ex vivo Mycobacterium tuberculosis- and Staphylococcus aureus-induced cytokine responses in peripheral blood mononuclear cells were used to assess trained immunity.RESULTSWhile BCG vaccination enhanced cytokine responses to restimulation, it reduced systemic inflammation. This effect was validated in 3 smaller cohorts, and was much stronger in men than in women. In addition, baseline circulating inflammatory markers were associated with ex vivo cytokine responses (trained immunity) after BCG vaccination.CONCLUSIONThe capacity of BCG to enhance microbial responsiveness while dampening systemic inflammation should be further explored for potential therapeutic applications.FUNDINGNetherlands Organization for Scientific Research, European Research Council, and the Danish National Research Foundation.

Circadian rhythm influences induction of trained immunity by BCG vaccination

BACKGROUNDThe antituberculosis vaccine bacillus Calmette-Guérin (BCG) reduces overall infant mortality. Induction of innate immune memory, also termed trained immunity, contributes toward protection against heterologous infections. Since immune cells display oscillations in numbers and function throughout the day, we investigated the effect of BCG administration time on the induction of trained immunity.METHODSEighteen volunteers were vaccinated with BCG at 6 pm and compared with 36 age- and sex-matched volunteers vaccinated between 8 am and 9 am. Peripheral blood mononuclear cells were stimulated with Staphylococcus aureus and Mycobacterium tuberculosis before, as well as 2 weeks and 3 months after, BCG vaccination. Cytokine production was measured to assess the induction of trained immunity and adaptive responses, respectively. Additionally, the influence of vaccination time on induction of trained immunity was studied in an independent cohort of 302 individuals vaccinated between 8 am and 12 pm with BCG.RESULTSCompared with evening vaccination, morning vaccination elicited both a stronger trained immunity and adaptive immune phenotype. In a large cohort of 302 volunteers, early morning vaccination resulted in a superior cytokine production capacity compared with later morning. A cellular, rather than soluble, substrate of the circadian effect of BCG vaccination was demonstrated by the enhanced capacity to induce trained immunity in vitro in morning- compared with evening-isolated monocytes.CONCLUSIONSBCG vaccination in the morning induces stronger trained immunity and adaptive responses compared with evening vaccination. Future studies should take vaccine administration time into account when studying specific and nonspecific effects of vaccines; early morning should be the preferred moment of BCG administration.FUNDINGThe Netherlands Organization for Scientific Research, the European Research Council, and the Danish National Research Foundation.

Activate: Randomized Clinical Trial of BCG Vaccination against Infection in the Elderly

BCG vaccination in children protects against heterologous infections and improves survival independently of tuberculosis prevention. The phase III ACTIVATE trial assessed whether BCG has similar effects in the elderly. In this double-blind, randomized trial, elderly patients (n = 198) received BCG or placebo vaccine at hospital discharge and were followed for 12 months for new infections. At interim analysis, BCG vaccination significantly increased the time to first infection (median 16 weeks compared to 11 weeks after placebo). The incidence of new infections was 42.3% (95% CIs 31.9%–53.4%) after placebo vaccination and 25.0% (95% CIs 16.4%–36.1%) after BCG vaccination; most of the protection was against respiratory tract infections of probable viral origin (hazard ratio 0.21, p = 0.013). No difference in the frequency of adverse effects was found. Data show that BCG vaccination is safe and can protect the elderly against infections. Larger studies are needed to assess protection against respiratory infections, including COVID-19 (ClinicalTrials.gov NCT03296423).

Heterotypic immunity against vaccinia virus in an HLA-B*07:02 transgenic mousepox infection model

Vaccination with vaccinia virus (VACV) elicits heterotypic immunity to smallpox, monkeypox, and mousepox, the mechanistic basis for which is poorly understood. It is generally assumed that heterotypic immunity arises from the presentation of a wide array of VACV-derived, CD8+ T cell epitopes that share homology with other poxviruses. Herein this assumption was tested using a large panel of VACV-derived peptides presented by HLA-B*07:02 (B7.2) molecules in a mousepox/ectromelia virus (ECTV)-infection, B7.2 transgenic mouse model. Most dominant epitopes recognized by ECTV- and VACV-reactive CD8+ T cells overlapped significantly without altering immunodominance hierarchy. Further, several epitopes recognized by ECTV-reactive CD8+ T cells were not recognized by VACV-reactive CD8+ T cells, and vice versa. In one instance, the lack of recognition owed to a N72K variation in the ECTV C4R70–78 variant of the dominant VACV B8R70–78 epitope. C4R70–78 does not bind to B7.2 and, hence, it was neither immunogenic nor antigenic. These findings provide a mechanistic basis for VACV vaccination-induced heterotypic immunity which can protect against Variola and Monkeypox disease. The understanding of how cross-reactive responses develop is essential for the rational design of a subunit-based vaccine that would be safe, and effectively protect against heterologous infection.

Inactivated influenza vaccine formulated with single-stranded RNA-based adjuvant confers mucosal immunity and cross-protection against influenza virus infection

Influenza vaccination is considered the most valuable means to prevent and control seasonal influenza infections, which causes various clinical symptoms, ranging from mild cough and fever to even death. Among various influenza vaccine types, the inactivated subunit type is known to provide improved safety with reduced reactogenicity. However, there are some drawbacks associated with inactivated subunit type vaccines, with the main ones being its low immunogenicity and the induction of Th2-biased immune responses. In this study, we investigated the role of a single-stranded RNA (ssRNA) derived from the intergenic region in the internal ribosome entry site of the Cricket paralysis virus as an adjuvant rather than the universal vaccine for a seasonal inactivated subunit influenza vaccine. The ssRNA adjuvant stimulated not only well-balanced cellular (indicated by IgG2a, IFN-γ, IL-2, and TNF-α) and humoral (indicated by IgG1 and IL-4) immune responses but also a mucosal immune response (indicated by IgA), a key protector against respiratory virus infections. It also increases the HI titer, the surrogate marker of influenza vaccine efficacy. Furthermore, ssRNA adjuvant confers cross-protective immune responses against heterologous influenza virus infection while promoting enhanced viral clearance. Moreover, ssRNA adjuvant increases the number of memory CD4+ and CD8+ T cells, which can be expected to induce long-term immune responses. Therefore, this ssRNA-adjuvanted seasonal inactivated subunit influenza vaccine might be the best influenza vaccine generating robust humoral and cellular immune responses and conferring cross-protective and long-term immunity.

Gilt Vaccination with a Mixed Administration of a PRRS MLV and a PPV1 Subunit Vaccine Protects against Heterologous PRRSV1 Infection and Prevents Detrimental Effects on Piglet Performance.

The efficacy of the combined administration of a porcine reproductive and respiratory syndrome (PRRS) modified live virus (MLV) vaccine and a porcine parvovirus 1 (PPV1) subunit vaccine in gilts was addressed in two experiments. Experiment A aimed to establish a 4-week onset of immunity (OOI). Gilts were randomly distributed in three treatment groups: non-vaccinated control animals (group 1), animals vaccinated with the combined vaccine (group 2), and a third group that consisted of animals vaccinated with the PRRS MLV vaccine alone (group 3). Four weeks after the first vaccination, gilts were challenged with a heterologous PRRS virus 1 (PRRSV1) and euthanized three weeks after. Besides this, experiment B pursued a 17-week duration of immunity (DOI). In this case, gilts were distributed in the same treatment groups, but for the third group, which consisted of non-vaccinated, non-challenged animals were used instead. For the DOI assessment, gilts were artificially inseminated 4 weeks after the first vaccination, challenged at day 90 of gestation, and followed up, together with their offspring, until day 20 post-farrowing. Serology and viremia post-challenge were determined in gilts from both experiments, while farrowing and piglet performance were only evaluated in experiment B. Overall, the combined vaccine helped to protect gilts from viremia post-challenge and, consequently, to prevent PRRS clinical symptoms and diminish the proportion of piglets infected congenitally or early in life. The combined vaccine also elicited a significant improvement in piglet survival rate and growth performance until weaning. The present results reveal efficacy and lack of interference of the mixed use of the tested vaccines against PRRSV1 infection, with at least 4-week OOI and 17-week DOI.

The optimal age of vaccination against dengue in Brazil based on serotype-specific forces of infection derived from serological data.

In this paper, we study a single serotype transmission model of dengue to determine the optimal vaccination age for Dengvaxia. The transmission dynamics are modelled with an age-dependent force of infection. The force of infection for each serotype is derived from the serological profile of dengue in Brazil without serotype distinction and from serotype-specific reported cases. The risk due to an infection is measured by the probability of requiring hospitalization based on Brazilian Ministry of Health data. The optimal vaccination age is determined for any number and combination of the four distinct dengue virus serotypes DENv1-4. The lifetime expected risk is adapted to include antibody dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections. The risk is assumed to be serostatus-dependent. The optimal vaccination age is computed for constant, serostatus-specific vaccine efficacies. Additionally, the vaccination age is restricted to conform to the licence of Dengvaxia in Brazil and the achievable and minimal lifetime expected risks are compared. The optimal vaccination age obtained for the risk of hospitalization varies significantly with the assumptions relating to ADE and cross-immunity. Risk-free primary infections lead to higher optimal vaccination ages, as do asymptomatic third and fourth infections. Sometimes vaccination is not recommended at all, e.g. for any endemic area with a single serotype if primary infections are risk-free. Restricting the vaccination age to Dengvaxia licensed ages mostly leads to only a slightly higher lifetime expected risk and the vaccine should be administered as close as possible to the optimal vaccination age.

BCG-Induced Trained Immunity in Healthy Individuals: The Effect of Plasma Muramyl Dipeptide Concentrations.

BCG vaccination protects not only against tuberculosis but also against heterologous infections. This effect differs between individuals, yet the factors responsible for this variation are unknown. BCG-induced nonspecific protection is, at least partially, mediated by innate immune reprogramming (trained immunity), which can be induced by the muramyl dipeptide (MDP) component of peptidoglycans. We aimed to study whether differential release of MDP in healthy individuals may explain variability of their response to BCG vaccination. Circulating MDP concentrations were increased up to three months after BCG vaccination. MDP concentrations at baseline, but not their increase postvaccination, positively correlated with the induction of trained immunity and not with mycobacteria-induced T-cell responses. Interestingly, MDP concentrations correlated with inflammatory markers in the circulation. In conclusion, circulating MDP concentrations are associated with the strength of trained immunity responses and thus influence the biological effects of BCG vaccination. This study increases our understanding about the role of MDP in BCG-induced trained immunity, which might help to optimize vaccine efficacy and explore novel applications of BCG vaccination.

Effective control of early Zika virus replication by Dengue immunity is associated to the length of time between the 2 infections but not mediated by antibodies.

Little is known about the contribution of virus-specific and cross-reacting antibodies (Abs) or the cellular immune response generated by a primary dengue (DENV) infection on the course of a secondary zika (ZIKV) infection in vivo. Here we show that the length of time between DENV/ZIKV infections has a qualitative impact on controlling early ZIKV replication. Depletion of DENV2-specific Abs in sera confirmed that those type-specific Abs do not contribute to ZIKV control. We show that the magnitude and durability of the neutralizing antibodies (nAbs) induced by a secondary ZIKV infection is modest compared to the response induced after a secondary heterologous DENV infection. Our in vivo results are showing a complex interplay between the cellular and innate immune responses characterized by a high frequency of plasmacytoid dendritic cells (pDC) correlating with an increase in the frequency of DENV antigen specific T cells and a significant control of ZIKV replication which is time dependent. Taken together, our results suggest that early after ZIKV infection other mechanisms such as the innate and cellular immune responses may play a predominant role in controlling ZIKV replication. Regardless of the time elapsed between infections there was no evidence of in vivo antibody-dependent enhancement (ADE) of ZIKV by DENV immunity. These findings have pivotal implications while interpreting ZIKV pathogenesis in flavivirus-experimented populations, diagnostic results interpretation and vaccine designs and schedules among others.

CD8+ T cell cross-reactivity during heterologous flavivirus infection results in cross-reactive immunodomination and enhanced cytolytic capacity at the expense of virus-specific responses

Abstract Flaviviruses constitute a genus of closely related arthropod-borne viruses including Zika virus, the four serotypes of dengue virus, and yellow fever virus, which circulate in the same geographic regions. These viruses share a substantial degree of genetic similarity and consequently, antigenic overlap has been reported by evaluating T cell and antibody responses in humans, non-human primates, and mice. However, it has not been determined how existing immunity to a heterologous flavivirus impacts functional immune responses to virus-specific and cross-reactive epitopes. We hypothesize that cross-reactive T cells from prior flavivirus exposures will expand robustly during a heterologous challenge and that these cells primed during a heterologous infection will be functionally different from cells of the same specificity primed during a homologous infection. Using various mouse models of flavivirus infection, we have identified a pan-flavivirus reactive CD8+ T cell epitope. We show in a heterologous infection model in which dengue virus exposure precedes Zika virus infection, T cell responses to the cross-reactive epitope dominate at the expense of the Zika-specific T cell responses. These cross-reactive T cells display enhanced killing capacity, in addition to other functional changes. The culmination of these features drive altered protective capacity when compared to homologously primed T cells in our mouse model of Zika infection. Our findings provide a mechanistic understanding of cross-reactive T cell control during heterologous infection and have important implications for vaccine design, as these results define the functional consequences of priming a cross-reactive T cell response for a pan-flavivirus vaccine.

Development of inactivated subunit influenza vaccine endowing with IgA induction and protection against heterologous strain

Abstract Vaccination is known to be the best way to prevent and control seasonal influenza infections. Among the various available influenza vaccines, an inactivated vaccine shows improved protective effects associated with greater safety. However, since the influenza virus is continuously evolving, its response to inactivated vaccines becomes increasingly difficult to predict, leading to complete or partial loss of protection against the virus. In addition, immunogenicity is lower than other types and Th2-biased immune responses have been reported. In this study, we have investigated the role of the single-stranded RNA (ssRNA) adjuvant derived from the intergenic region of internal ribosome entry site of Cricket Paralysis virus in seasonal inactivated subunit influenza vaccine (ISIV). We found that the ssRNA adjuvant stimulated balanced cellular (indicated by IgG2a, IFN-γ, IL-2, and TNF-α) and humoral (indicated by IgG1 and HI) responses, along with mucosal (indicated by IgA) immune response. Moreover, the ssRNA adjuvant formulated ISIV enhanced viral clearance and improved lung pathology after homologous and even heterologous influenza virus infections. The proportion of memory CD4+ and CD8+ T cells, important for long term immunity, was also observed to increase. Therefore, the ssRNA adjuvant formulated ISIV is effective in inducing humoral and cellular immune responses, cross protection, and long-term immunity.

Adaptive γδ T cell function is subverted by Yersinia pseudotuberculosis outer proteins

Abstract γδ T cells are an unconventional subset of multifunctional T cells enriched in mucosal barrier tissues. After foodborne Listeria monocytes (Lm) infection, an activated CD44hiCD27loVγ4 subset of γδ T cells formed in the mesenteric lymph nodes (MLN) that shared numerous characteristics with traditional T cells including anamnestic responses. While attempting to uncover the specificity of Lm-elicited memory cells utilizing heterologous challenge infections we observed that Lm-elicited γδ T cell function was induced with heat-killed Yersinia pseudotuberculosis (Yptb) but not live Yptb suggesting that Yptb employs immune evasion strategies to limit anti-pathogen adaptive γδ T cell functions. Live Yptb inhibited CD44hiCD27loVγ4 T cell IL-17A and IFNγ production integral for anti-pathogen immunity. Tracking Yptb translocation through a FRET-based reporter assay revealed preferential translocation of Yptb outer proteins (Yop) into adaptive γδ T cells over conventional T cells and an abrogated cytokine response compared to their non-translocated counterparts within the same environment. Using a series of Yptb mutants deficient in translocated effector proteins, we determined that YopH inhibited IL-17A production while YopJ inhibited IFNγ production. Inhibition of Stat4 phosphorylation in γδ T cells was observed in a translocation, YopJ, and IL-12/IL-23p40 dependent manner, suggesting that YopJ inhibits IFNγ production through Stat4 phosphorylation. Collectively, these data demonstrate direct inhibitory mechanisms of γδ T cell function mediated by the Yptb effectors YopH and YopJ and identify an unknown pathogenesis pathway utilized by Yptb to subvert immune function.

Pathogen-elicited memory γδ T cells express a broadly reactive canonical TCR or a pathogen-specific non-canonical TCR

Abstract γδ T cells are critical sentinels protecting barrier surfaces against pathogens. However, our understanding of γδ T cell specificity remains limited. We previously identified a resident memory Vγ4Vδ1 T cell population elicited by foodborne Listeria monocytogenes (Lm) infection. Analysis of the CDR3δ sequences revealed that a large subset of non-canonical clones expanded during primary Lm infection, contracted during memory homeostasis and recalled after secondary Lm infection suggesting antigenic-specificity may be involved in this response. However, most of the response was elicited by cells bearing a canonical Vδ1 TCR suggesting that many Lm-elicited cells may not be Lm-specific. Indeed, stimulation of mesenteric lymph node cells from Lm-immune mice with diverse pathogens induced a functional response by Lm-elicited memory γδ T cells. Similarly, induction of Salmonella colitis (STm-colitis) in Lm-immune mice resulted in a TCR-dependent γδ T cell recall-like response, demonstrating that the majority of these memory cells respond to heterologous infection. Interestingly, most of the non-canonical γδ T cell clones that responded to Lm infection did not expand in response to STm-colitis suggesting some level of specificity is imparted by the priming pathogen. Importantly, other enteropathogens triggered a recall-like response of Lm-elicited memory γδ T cells. Adaptive γδ T cells were also generated after foodborne infection of germ-free mice and in response to diverse bacterial infections of SPF mice, indicating that this population can be induced by a broad range of disseminating pathogens and may provide a broad target for universal mucosal vaccines of the gut.

Early-life heterologous rhinovirus infections induce an exaggerated asthma-like phenotype

Early-life wheezing-associated respiratory tract infection by rhinovirus (RV) is a risk factor for asthma development. Infants are infected with many different RV strains per year. We previously showed that RV infection of 6-day-old BALB/c mice induces a mucous metaplasia phenotype that is dependent on type 2 innate lymphoid cells (ILC2s). We hypothesized that early-life RV infection alters the response to subsequent heterologous infection, inducing an exaggerated asthma-like phenotype. Wild-type BALB/c mice and Rorafl/flIl7rcre mice lacking ILC2s were treated as follows: (1) sham on day 6 of life plus sham on day 13 of life, (2) RV-A1B on day 6 plus sham on day 13, (3) sham on day 6 plus RV-A2 on day 13, and (4) RV-A1B on day 6 plus RV-A2 on day 13. Mice infected with RV-A1B at day 6 and sham at day 13 showed an increased number of bronchoalveolar lavage eosinophils and increased expression of IL-13 mRNA but not expression of IFN-γ mRNA (which is indicative of a type 2 immune response), whereas mice infected with sham on day 6 and RV-A2 on day 13 of life demonstrated increased IFN-γ expression (which is a mature antiviral response). In contrast, mice infected with RV-A1B on day 6 before RV-A2 infection on day 13 showed increased expression of IL-13, IL-5, Gob5, Muc5b, and Muc5ac mRNA; increased numbers of eosinophils and IL-13-producing ILC2s; and exaggerated mucus metaplasia and airway hyperresponsiveness. Compared with Rorafl/fl mice, Rorafl/flIl7rcre mice showed complete suppression of bronchoalveolar lavage eosinophils and mucous metaplasia. Early-life RV infection alters the response to subsequent heterologous infection, inducing an intensified asthma-like phenotype that is dependent on ILC2s.

A single lentivector DNA based immunization contains a late heterologous SIVmac251 mucosal challenge infection

Variety of conventional vaccine strategies tested against HIV-1 have failed to induce protection against HIV acquisition or durable control of viremia. Therefore, innovative strategies that can induce long lasting protective immunity against HIV chronic infection are needed. Recently, we developed an integration-defective HIV lentiDNA vaccine that undergoes a single cycle of replication in target cells in which most viral antigens are produced. A single immunization with such lentiDNA induced long-lasting T-cell and modest antibody responses in cynomolgus macaques. Here eighteen months after this single immunization, all animals were subjected to repeated low dose intra-rectal challenges with a heterologous pathogenic SIVmac251 isolate. Although the viral set point in SIVmac-infected cynomolgus is commonly lower than that seen in Indian rhesus macaques, the vaccinated group of macaques displayed a two log reduction of peak of viremia followed by a progressive and sustained control of virus replication relative to control animals. This antiviral control correlated with antigen-specific CD4+ and CD8+ T cells with high capacity of recall responses comprising effector and central memory T cells but also memory T cell precursors. This is the first description of SIV control in NHP model infected at 18 months following a single immunization with a non-integrative single cycle lentiDNA HIV vaccine. While not delivering sterilizing immunity, our single immunization strategy with a single-cycle lentivector DNA vaccine appears to provide an interesting and safe vaccine platform that warrants further exploration.

The Optimal Age of Vaccination Against Dengue with an Age-Dependent Biting Rate with Application to Brazil

In this paper we introduce a single serotype transmission model, including an age-dependent mosquito biting rate, to find the optimal vaccination age against dengue in Brazil with Dengvaxia. The optimal vaccination age and minimal lifetime expected risk of hospitalisation are found by adapting a method due to Hethcote (Math Biosci 89:29–52). Any number and combination of the four dengue serotypes DENv1–4 is considered. Successful vaccination against a serotype corresponds to a silent infection. The effects of antibody-dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections are studied. ADE is assumed to imply risk-free primary infections, while permanent cross-immunity implies risk-free tertiary and quaternary infections. Data from trials of Dengvaxia indicate vaccine efficacy to be age and serostatus dependent and vaccination of seronegative individuals to induce an increased risk of hospitalisation. Some of the scenarios are therefore reconsidered taking these findings into account. The optimal vaccination age is compared to that achievable under the current age restriction of the vaccine. If vaccination is not considered to induce risk, optimal vaccination ages are very low. The assumption of ADE generally leads to a higher optimal vaccination age in this case. For a single serotype vaccination is not recommended in the case of ADE. Permanent cross-immunity results in a slightly lower optimal vaccination age. If vaccination induces a risk, the optimal vaccination ages are much higher, particularly for permanent cross-immunity. ADE has no effect on the optimal vaccination age when permanent cross-immunity is considered; otherwise, it leads to a slight increase in optimal vaccination age.

Deteksi Interleukin-10 (IL-10) pada Mice Balb/C yang diinfeksi dengan Virus Dengue: Telaah patogenesis antara teori infeksi sekunder dan virulensi

Since the pathogenesis/immunopathogenesis of vasculopathy plasma leakage in DHF/ DSS was not clearly understood, this study was conducted. Considering the equilibrium between pro and anti inflammatory cytokine in homeostatic process in inflammation, this study was aimed to; first, detect the increase of secretion of IL-10 of immune responses of Mice Balb/c that were challenged with dengue virus serotype Den-1 & Den-3. Second, compare the secretion of IL-10 of immune responses of Mice Balb/c that were challenged with dengue viruses in primary infection, secondary monospecific infection and secondary heterologous infection. This study was experimental laboratory, with randomised pretest-posttest with spread control group design. Balb/C mice were used as animal laboratory models. The dengue viruses Den-1 & Den-3 that used in this study were isolated from dengue suspected patients and the viruses were innoculated and bred in BHK 21 clone 13 cell line, before they were injected to the models. Serum samples were collected from blood by centrifuging the blood for 10 minutes at 1000 rpm. The data of this experiment were obtained by applying the serum samples in Murine IL-10 Elisa Kit product of Diaclone Research France. In primary infection, significant increase of IL-10 mean titer in experimental group challenged with dengue viruses Den-1 was obtained (p=0.03) compared with the control group. Conversely the experimental group challenged with dengue viruses Den-3 showed no significant increase of mean titer (p=0.127). In the secondary infection, group treated with dengue Viruses Den-1 showed decrease of mean titer of IL-10 (p=0.034 & p=0.003). Meanwhile, group treated with dengue Viruses Den-3 showed no significant different compared to primary infection group (p=0.571&p=0.359). The results of the study, support both virulence theory and the secondary heterologous dengue infection theory.

Sequential Immunization With Heterologous Viruses Does Not Result in Attrition of the B Cell Memory in Rainbow Trout.

Long-term immunity is of great importance for protection against pathogens and has been extensively studied in mammals. Successive heterologous infections can affect the maintenance of immune memory, inducing attrition of T memory cells and diminishing B cell mediated protection. In fish, the basis of immune memory and the mechanisms of immunization to heterologous pathogens remain poorly understood. We sequentially immunized isogenic rainbow trout with two immunologically distinct viruses, VHSV and IPNV, either with one virus only or in combination, and analyzed the antibody responses and repertoires. Neutralizing antibodies and ELISPOT did not reveal an effect of heterologous immunization. Using a consensus read sequencing approach that incorporates unique barcodes to each cDNA molecule, we focused on the diversity expressed by selected responding VH/C combinations. We identified both public and private responses against VHSV and/or IPNV in all groups of fish. In fish immunized with two viruses, we registered no significant reduction in the persistence of the response toward the primary immunization. Similarly, the response to the second immunization was not affected by a prior vaccination to the other virus. Our data suggest that heterologous immunization does not enforce attrition of pre-existing antibody producing cells, which may impair the protection afforded by multiple successive vaccinations. These observations are potentially important to improve vaccination strategies practiced in aquaculture.

Cross-Protective Abilities of Hyaluronic Acid Modified with Tetraglycine-l-octaarginine as a Mucosal Adjuvant against Infection with Heterologous Influenza Viruses.

Mucosal vaccination, which secretion of immunoglobulin A (IgA) on the mucosa is accompanied by induction of immunoglobulin G (IgG) in the blood, is one of the most effective ways to circumvent influenza epidemics caused by incorrect prediction of epidemic viral strains or viral mutation. Secreted IgA is expected to prevent hosts from being infected with heterologous viruses because this antibody cross-reacts to strains other than those used for immunization. Our previous mouse experiments revealed that intranasal IgA with cross-reactivity was induced through nasal inoculation with inactivated whole viral particles of the H1N1 A/New Caledonia/20/99 IVR116 (NCL) strain in the presence of hyaluronic acid modified with tetraglycine-l-octaarginine. In the present study, heterologous influenza virus challenge was performed to validate a potential of the hyaluronic acid derivative as a mucosal adjuvant with cross-protective abilities. Serious weight loss was observed when mice were nasally inoculated with inactivated NCL viruses alone and subsequently exposed to mouse-adapted infectious viruses of the H1N1 A/Puerto Rico/8/34 (PR8) strain. The symptom associated with virus infection was hardly ever observed for mice inoculated with a mixture of the viral antigens and tetraglycine-l-octaarginine-linked hyaluronic acid, presumably due to high induction of IgG and IgA capable of cross-reacting to PR8 viruses. Less proliferation of PR8 viruses in those mice was also supported by an insignificant elevation of antibody levels through virus exposure. Our polysaccharide derivative enabled hosts to acquire adaptive immunity with cross-protective abilities against heterologous virus infection.

Kinetics and Phenotype of the CD4 T Cell Response to Influenza Virus Infections.

Influenza A virus (IAV) is a leading cause of respiratory infections, with increased risk of severe illness and death in the very young, aged, and immunocompromised individuals. In both mice and humans, IAV-specific T cell responses are protective during primary as well as homologous and heterologous challenge infections. Many mouse studies have focused on CD4 T cells specific for a single, known model or IAV antigen. However, studies have demonstrated that the IAV-specific CD4 T cell response comprises many epitopes spread across multiple viral proteins. Therefore, herein we track the antigen-experienced CD4 T cell response using the surrogate markers CD49d and CD11a. This novel surrogate marker method allows us to characterize the full IAV-specific CD4 T cell response without the potential bias that could occur when examining an individual Ag-specificity. Our findings demonstrate that the immunodominant I-Ab-binding NP311−325 epitope often used in studies of IAV-specific CD4 T cells represents only about 5% of the total IAV-specific CD4 T cell response. Further, we find that the kinetics of the full pulmonary CD4 T cell response is similar to that of NP311-specific T cells and that the full CD4 T cell response in the lungs is predominantly composed of cells expressing the Th1 transcription factor T-bet, with smaller but significant portions of the response expressing the Treg and Tfh associated transcription factors Foxp3 and Bcl-6, respectively. Interestingly, although Th1 cells are the most abundant Th subset in the lungs of both BALB/c and C57Bl/6 mice following IAV, the relative abundance of Treg and Tfh is reversed in the different mouse strains. In BALB/c mice, Foxp3+ cells are more abundant than Bcl6+ cells, whereas in C57Bl/6 mice, there are more Bcl6+ cells. As a whole, these data highlight the diversity of the endogenous CD4 T cell response to a primary IAV infection, providing an important context for past and future studies of the IAV-specific CD4 T cell response.