RESUMEN
Human respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infection in children under 5 y of age. In the absence of a safe and effective vaccine and with limited options for therapeutic interventions, uncontrolled epidemics of RSV occur annually worldwide. Existing RSV reverse genetics systems have been predominantly based on older laboratory-adapted strains such as A2 or Long. These strains are not representative of currently circulating genotypes and have a convoluted passage history, complicating their use in studies on molecular determinants of viral pathogenesis and intervention strategies. In this study, we have generated reverse genetics systems for clinical isolates of RSV-A (ON1, 0594 strain) and RSV-B (BA9, 9671 strain) in which the full-length complementary DNA (cDNA) copy of the viral antigenome is cloned into a bacterial artificial chromosome (BAC). Additional recombinant (r) RSVs were rescued expressing enhanced green fluorescent protein (EGFP), mScarlet, or NanoLuc luciferase from an additional transcription unit inserted between the P and M genes. Mutations in antigenic site II of the F protein conferring escape from palivizumab neutralization (K272E, K272Q, S275L) were investigated using quantitative cell-fusion assays and rRSVs via the use of BAC recombineering protocols. These mutations enabled RSV-A and -B to escape palivizumab neutralization but had differential impacts on cell-to-cell fusion, as the S275L mutation resulted in an almost-complete ablation of syncytium formation. These reverse genetics systems will facilitate future cross-validation efficacy studies of novel RSV therapeutic intervention strategies and investigations into viral and host factors necessary for virus entry and cell-to-cell spread.
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Farmacorresistencia Viral/genética , Mutación , Virus Sincitiales Respiratorios/genética , Animales , Antivirales/toxicidad , Chlorocebus aethiops , Farmacorresistencia Viral/inmunología , Células Hep G2 , Humanos , Palivizumab/toxicidad , Infecciones por Virus Sincitial Respiratorio/tratamiento farmacológico , Infecciones por Virus Sincitial Respiratorio/virología , Virus Sincitiales Respiratorios/inmunología , Virus Sincitiales Respiratorios/aislamiento & purificación , Virus Sincitiales Respiratorios/patogenicidad , Genética Inversa/métodos , Células VeroRESUMEN
We developed an ELISPOT assay for evaluating Middle East respiratory syndrome coronavirus (MERS-CoV)âspecific T-cell responses in dromedary camels. After single modified vaccinia virus Ankara-MERS-S vaccination, seropositive camels showed increased levels of MERS-CoVâspecific T cells and antibodies, indicating suitability of camel vaccinations in disease-endemic areas as a promising approach to control infection.
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Camelus , Infecciones por Coronavirus , Linfocitos T , Vacunas Virales , Animales , Camelus/inmunología , Linfocitos T/inmunología , Coronavirus del Síndrome Respiratorio de Oriente Medio , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/prevención & control , Infecciones por Coronavirus/veterinaria , Vacunas Virales/inmunología , Vacunación/veterinaria , Ensayo de Immunospot Ligado a Enzimas , Anticuerpos AntiviralesRESUMEN
Influenza viruses are notorious for their capacity to evade host immunity. Not only can they evade recognition by virus-neutralizing antibodies, there is also evidence that they accumulate mutations in epitopes recognized by virus-specific CD8+T cells. In addition, we have shown previously that human influenza A viruses were less well recognized than avian influenza viruses by CD8+T cells directed to the highly conserved, HLA-A*02:01 restricted M158-66 epitope located in the Matrix 1 (M1) protein. Amino acid differences at residues outside the epitope were responsible for the differential recognition, and it was hypothesized that this reflected immune adaptation of human influenza viruses to selective pressure exerted by M158-66-specific CD8+T cells in the human population. In the present study, we tested this hypothesis and investigated if selective pressure exerted by M158-66 epitope-specific CD8+T cells could drive mutations at the extra-epitopic residues in vitro. To this end, isogenic influenza A viruses with the M1 gene of a human or an avian influenza virus were serially passaged in human lung epithelial A549 cells that transgenically express the HLA-A*02:01 molecule or not, in the presence or absence of M158-66 epitope-specific CD8+T cells. Especially in the virus with the M1 gene of an avian influenza virus, variants emerged with mutations at the extra-epitopic residues associated with reduced recognition by M158-66-specific T cells as detected by Next Generation Sequencing. Although the emergence of these variants was observed in the absence of selective pressure exerted by M158-66 epitope-specific CD8+T cells, their proportion was much larger in the presence of this selective pressure.
Asunto(s)
Fluprednisolona/análogos & derivados , Virus de la Influenza A , Gripe Aviar , Animales , Humanos , Sustitución de Aminoácidos , Epítopos de Linfocito T , Linfocitos T CD8-positivos , Virus de la Influenza A/genética , Antígenos HLA-A/genética , Antígenos HLA-A/metabolismoRESUMEN
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by RVF virus (RVFV). RVFV infections in humans are usually asymptomatic or associated with mild febrile illness, although more severe cases of haemorrhagic disease and encephalitis with high mortality also occur. Currently, there are no licensed human vaccines available. The safety and efficacy of a genetically engineered four-segmented RVFV variant (hRVFV-4s) as a potential live-attenuated human vaccine has been tested successfully in mice, ruminants, and marmosets though the correlates of protection of this vaccine are still largely unknown. In the present study, we have assessed hRVFV-4s-induced humoral and cellular immunity in a mouse model of RVFV infection. Our results confirm that a single dose of hRVFV-4s is highly efficient in protecting naïve mice from developing severe disease following intraperitoneal challenge with a highly virulent RVFV strain and data show that virus neutralizing (VN) serum antibody titres in a prime-boost regimen are significantly higher compared to the single dose. Subsequently, VN antibodies from prime-boost-vaccinated recipients were shown to be protective when transferred to naïve mice. In addition, hRVFV-4s vaccination induced a significant virus-specific T cell response as shown by IFN-γ ELISpot assay, though these T cells did not provide significant protection upon passive transfer to naïve recipient mice. Collectively, this study highlights hRVFV-4s-induced VN antibodies as a major correlate of protection against lethal RVFV infection.
Asunto(s)
Anticuerpos Neutralizantes , Anticuerpos Antivirales , Fiebre del Valle del Rift , Virus de la Fiebre del Valle del Rift , Vacunas Atenuadas , Vacunas Virales , Animales , Virus de la Fiebre del Valle del Rift/inmunología , Virus de la Fiebre del Valle del Rift/genética , Fiebre del Valle del Rift/prevención & control , Fiebre del Valle del Rift/inmunología , Vacunas Virales/inmunología , Vacunas Virales/administración & dosificación , Ratones , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/inmunología , Femenino , Vacunas Atenuadas/inmunología , Vacunas Atenuadas/administración & dosificación , Modelos Animales de Enfermedad , Inmunidad Celular , Linfocitos T/inmunología , Inmunidad Humoral , Ratones Endogámicos BALB C , Interferón gamma/inmunología , VacunaciónRESUMEN
Tick-borne encephalitis virus (TBEV) vaccine breakthrough (VBT) infections are not uncommon in endemic areas. The clinical and immunological outcomes have been poorly investigated. We assessed the magnitude and specificity of virus-specific antibody and T cell responses after TBE in previously vaccinated subjects and compared the results with those of unvaccinated TBE patients and study subjects that received vaccination without VBT infection. Symptomatic TBEV infection of unvaccinated study subjects induced virus-specific antibody responses to the E protein and non-structural protein 1 (NS1) as well as T cell responses to structural and other non-structural (NS) proteins. After VBT infections, significantly impaired NS1-specific antibody responses were observed, while the virus-specific T cell responses to the NS proteins were relatively strong. VBT infection caused predominantly moderate to severe disease during hospitalization. The level of TBEV EDIII- and NS1-specific antibodies in unvaccinated convalescent patients inversely correlated with TBE severity and neurological symptoms early after infection.
RESUMEN
Tick-borne encephalitis virus (TBEV) infection may cause acute central nervous system inflammation varying in clinical manifestations and severity. A possible correlation of TBEV-specific antibody and cell-mediated immune responses, shortly after infection, with clinical manifestations, severity and long-term outcome has been poorly investigated. In a cohort of thirty early tick-borne encephalitis (TBE) patients, we assessed the magnitude, specificity and functional properties of TBEV-specific T-cell and antibody responses. These responses early during disease were assessed in view of clinical manifestations, severity and long-term outcome. TBEV-specific T-cell responses to C, E, NS1, and NS5 proteins were significantly lower in patients with severe acute illness than in patients with mild TBE. Lower T-cell responses to E, NS1, and NS5 proteins also correlated with the development of meningoencephalomyelitis. Virus-specific antibody titres early after infection did not correlate with disease severity, clinical manifestations, or long-term outcome in this study, possibly due to the small number of patients of which matching serum and peripheral blood mononuclear cells were available. The findings suggest that virus-specific T cells afford a certain degree of protection against the development of severe TBEV-induced disease.
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Anticuerpos Antivirales , Virus de la Encefalitis Transmitidos por Garrapatas , Encefalitis Transmitida por Garrapatas , Linfocitos T , Encefalitis Transmitida por Garrapatas/inmunología , Encefalitis Transmitida por Garrapatas/virología , Virus de la Encefalitis Transmitidos por Garrapatas/inmunología , Humanos , Linfocitos T/inmunología , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Masculino , Femenino , Persona de Mediana Edad , Adulto , Índice de Severidad de la Enfermedad , Anciano , Proteínas no Estructurales Virales/inmunologíaRESUMEN
Introduction: Naturally attenuated Langat virus (LGTV) and highly pathogenic tick-borne encephalitis virus (TBEV) share antigenically similar viral proteins and are grouped together in the same flavivirus serocomplex. In the early 1970s, this has encouraged the usage of LGTV as a potential live attenuated vaccine against tick-borne encephalitis (TBE) until cases of encephalitis were reported among vaccinees. Previously, we have shown in a mouse model that immunity induced against LGTV protects mice against lethal TBEV challenge infection. However, the immune correlates of this protection have not been studied. Methods: We used the strategy of adoptive transfer of either serum or T cells from LGTV infected mice into naïve recipient mice and challenged them with lethal dose of TBEV. Results: We show that mouse infection with LGTV induced both cross-reactive antibodies and T cells against TBEV. To identify correlates of protection, Monitoring the disease progression in these mice for 16 days post infection, showed that serum from LGTV infected mice efficiently protected from developing severe disease. On the other hand, adoptive transfer of T cells from LGTV infected mice failed to provide protection. Histopathological investigation of infected brains suggested a possible role of microglia and T cells in inflammatory processes within the brain. Discussion: Our data provide key information regarding the immune correlates of protection induced by LGTV infection of mice which may help design better vaccines against TBEV.
Asunto(s)
Virus de la Encefalitis Transmitidos por Garrapatas , Encefalitis Transmitida por Garrapatas , Infecciones por Flavivirus , Ratones , Animales , Anticuerpos , Encéfalo , Vacunas AtenuadasRESUMEN
Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is effective in preventing COVID-19 hospitalization and fatal outcome. However, several studies indicated that there is reduced vaccine effectiveness among older individuals, which is correlated with their general health status1,2. How and to what extent age-related immunological defects are responsible for the suboptimal vaccine responses observed in older individuals receiving SARS-CoV-2 messenger RNA vaccine, is unclear and not fully investigated1,3-5. In this observational study, we investigated adaptive immune responses in adults of various ages (22-99 years old) receiving 2 doses of the BNT162b2 mRNA vaccine. Vaccine-induced Spike-specific antibody, and T and memory B cell responses decreased with increasing age. These responses positively correlated with the percentages of peripheral naïve CD4+ and CD8+ T cells and negatively with CD8+ T cells expressing signs of immunosenescence. Older adults displayed a preferred T cell response to the S2 region of the Spike protein, which is relatively conserved and a target for cross-reactive T cells induced by human 'common cold' coronaviruses. Memory T cell responses to influenza virus were not affected by age-related changes, nor the SARS-CoV-2-specific response induced by infection. Collectively, we identified signs of immunosenescence correlating with the outcome of vaccination against a new viral antigen to which older adults are immunologically naïve. This knowledge is important for the management of COVID-19 infections in older adults.
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COVID-19 , Inmunosenescencia , Humanos , Anciano , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano de 80 o más Años , Vacuna BNT162 , Linfocitos T CD8-positivos , COVID-19/prevención & control , Vacunas contra la COVID-19 , SARS-CoV-2/genética , Vacunación , ARN Mensajero/genéticaRESUMEN
Despite lockdown measures, intense symptom-based PCR, and antigen testing, the SARS-CoV-2 pandemic spread further. In this open observational study conducted in Lower Saxony, Germany, voluntary SARS-CoV-2 PCR tests were performed from April 2020 until June 2021, supported by serum antibody testing to prove whether PCR testing in subjects with none or few symptoms of COVID-19 is a suitable tool to manage the pandemic. In different mobile stations, 4,817 subjects from three different working fields participated in the PCR testing. Serum antibody screening using the SARS-CoV-2 ViraChip IgG (Viramed, Germany) and the Elecsys Anti-SARS-CoV-2 assay (Roche, Germany) was performed alongside virus neutralization testing. Subjects were questioned regarding comorbidities and COVID-19 symptoms. Fifty-one subjects with acute SARS-CoV-2 infection were detected of which 31 subjects did not show any symptoms possibly characteristic for COVID-19. An additional 37 subjects reported a previous SARS-CoV-2 infection (total prevalence 1.82%). Seroconversion was discovered in 58 subjects with known SARS-CoV-2 infection and in 58 subjects that never had a positive PCR test. The latter had a significantly lower Charlson Comorbidity Index, and one third of them were asymptomatic. In 50% of all seroconverted subjects, neutralizing serum antibodies (NAbs) were detectable in parallel to N/S1 (n = 16) or N/S1/S2 antigen specific antibodies (n = 40) against SARS-CoV-2. NAb titers decreased within 100 days after PCR-confirmed SARS-CoV-2 acute infection by at least 2.5-fold. A relatively high rate of subclinical SARS-CoV-2 infections may contribute to the spread of SARS-CoV-2, suggesting that in addition to other intervention strategies, systematic screening of asymptomatic persons by PCR testing may significantly enable better pandemic control. IMPORTANCE Within this open observational study, repeated PCR (n > 4,700) and antibody screening (n > 1,600) tests were offered in three different working fields. The study identified 51 subjects with acute SARS-CoV-2 infection and 37 subjects reported to have had a positive PCR test taken externally. Thirty-one of the 51 subjects did not display any symptoms prior to testing. In addition, 58 subjects without PCR-confirmed SARS-CoV-2 infection were identified by seroconversion. Subjects, that had undergone SARS-CoV-2 infection without having noticed, more often had a low grade of immunization with no NAbs, but may have relevantly contributed to the spread of the pandemic. Based on these results, we suggest that both regular PCR and rapid test screening of symptomatic and asymptomatic individuals, specifically within groups or workplaces identifiable as having close quarter contact, thus increased infection transference risk, is necessary to better assess and therefore reduce the spread of a pandemic virus.
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Anticuerpos Antivirales/sangre , COVID-19/epidemiología , COVID-19/virología , SARS-CoV-2/genética , SARS-CoV-2/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades Asintomáticas , COVID-19/sangre , Prueba Serológica para COVID-19 , Alemania/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Estudios Prospectivos , SARS-CoV-2/aislamiento & purificación , SARS-CoV-2/fisiología , Seroconversión , Adulto JovenRESUMEN
BACKGROUND: Detection of seroconversion after SARS-CoV-2-infection or vaccination is relevant to discover subclinical cases and recognize patients with a possible immunity. OBJECTIVES: Test performance, effects of age, time-point of seroconversion and immune status regarding neutralizing antibodies (NAbs) and T-cell-reactivity were investigated. STUDY DESIGN: Two antibody assays (Viramed-Test for S/N-specific IgG, Roche-Test for N-specific IgA, -M, -G) were evaluated with classified samples. In total, 381 subjects aged 6-99 years, who had either recovered from the disease or had been vaccinated, were screened for SARS-CoV-2-specific antibodies. This screening was part of an open observational study with working adults. Additionally, children and adults were analyzed in a longitudinal COVID-19 study in schools. For immunity evaluation, virus neutralization tests and ELISpot tests were performed in a subgroup of subjects. RESULTS: Viramed revealed a slightly lower test performance than Roche, but test quality was equally well in samples from very young or very old donors. The time-point of seroconversion after the respective immunization detected by the two tests was not significantly different. N-specific antibodies, detected with Roche, highly correlated with NAbs in recovered subjects, whereas a positive Viramed-Test result was paralleled by a positive ELISpot result. CONCLUSION: Viramed-Test was not as sensitive as Roche-Test, but highly specific and beneficial to distinguish between recovered and vaccinated status. For both tests correlations with humoral and cellular immunity were found. Of note, the expected early detection of IgA and IgM by the Roche-Test did not prove to be an advantage over IgG testing by Viramed.
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COVID-19 , SARS-CoV-2 , Adulto , Niño , Humanos , COVID-19/diagnóstico , Sensibilidad y Especificidad , Anticuerpos Antivirales , Anticuerpos Neutralizantes , Inmunoglobulina G , Inmunoglobulina ARESUMEN
Immunosenescence is a process associated with aging that leads to dysregulation of cells of innate and adaptive immunity, which may become dysfunctional. Consequently, older adults show increased severity of viral and bacterial infections and impaired responses to vaccinations. A better understanding of the process of immunosenescence will aid the development of novel strategies to boost the immune system in older adults. In this review, we focus on major alterations of the immune system triggered by aging, and address the effect of chronic viral infections, effectiveness of vaccination of older adults and strategies to improve immune function in this vulnerable age group.
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Envejecimiento/inmunología , Interacciones Huésped-Patógeno/inmunología , Inmunidad , Virosis/inmunología , Inmunidad Adaptativa , Factores de Edad , Animales , Toma de Decisiones Clínicas , Manejo de la Enfermedad , Susceptibilidad a Enfermedades/inmunología , Humanos , Sistema Inmunológico/inmunología , Sistema Inmunológico/metabolismo , Inmunidad Innata , Virosis/terapia , Virosis/virologíaRESUMEN
Currently, infections with SARS-Coronavirus-2 (SARS-CoV-2), the causative agent of the COVID-19 pandemic, are responsible for substantial morbidity and mortality worldwide. Older adults subjects > 60 years of age account for > 95% of the over one million fatal cases reported to date. It is unclear why in this age group SARS-CoV-2 infection causes more severe disease than in young adults. We hypothesized that differences in SARS-CoV-2 cross-reactive cellular immunity induced after infection with human coronaviruses (HCoVs), like OC43 and NL63, were at the basis of the differential mortality (and morbidity) observed after SARS-CoV-2 infection, because a small proportion of HCoV-specific T cells cross-react with SARS-CoV-2. Our data demonstrate that pre-existing T cell immunity induced by circulating human alpha- and beta-HCoVs is present in young adult individuals, but virtually absent in older adult subjects. Consequently, the frequency of cross-reactive T cells directed to the novel pandemic SARS-CoV-2 was minimal in most older adults. To the best of our knowledge, this is the first time that the presence of cross-reactive T cells to SARS-CoV-2 is compared in young and older adults. Our findings provide at least a partial explanation for the more severe clinical outcome of SARS-CoV-2 infection observed in the elderly. Moreover, this information could help to design efficacious vaccines for this age group, aiming at the induction of cell-mediated immunity.
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Anticuerpos Antivirales/inmunología , Coronavirus Humano NL63/inmunología , Coronavirus Humano OC43/inmunología , SARS-CoV-2/inmunología , Linfocitos T/inmunología , Adulto , Anciano , COVID-19/inmunología , COVID-19/patología , Reacciones Cruzadas/inmunología , Humanos , Inmunidad Celular/inmunología , Persona de Mediana Edad , Índice de Severidad de la Enfermedad , Glicoproteína de la Espiga del Coronavirus/inmunología , Adulto JovenRESUMEN
INTRODUCTION: Various viruses, including poxviruses, adenoviruses and vesicular stomatitis virus, have been considered as vaccine vectors for the delivery of antigens of interest in the development of vaccines against newly emerging pathogens. AREAS COVERED: Here, we review results that have been obtained with influenza A viruses (IAV) as vaccine vectors. With the advent of reverse genetics technology, IAV-based recombinant vaccine candidates have been constructed that induce protective immunity to a variety of different pathogens of interest, including West Nile virus, Plasmodium falciparum and respiratory syncytial virus. The various cloning strategies to produce effective and attenuated, safe to use IAV-based viral vectors are discussed. EXPERT COMMENTARY: It was concluded that IAV-based vector system has several advantages and holds promise for further development.
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Vectores Genéticos , Virus de la Influenza A/genética , Malaria Falciparum/prevención & control , Infecciones por Virus Sincitial Respiratorio/prevención & control , Vacunas Sintéticas/inmunología , Fiebre del Nilo Occidental/prevención & control , Humanos , Plasmodium falciparum/inmunología , Virus Sincitiales Respiratorios/inmunología , Genética Inversa , Vacunas Atenuadas/inmunología , Virus del Nilo Occidental/inmunologíaRESUMEN
Effective vaccines are the cornerstone of our defenses against acute influenza virus infections that result in â¼500 000 annual deaths worldwide. For decades, an on-going concerted effort has been to develop a universal influenza vaccine to combat the looming threat of potentially pandemic emerging and re-emerging influenza viruses. To address the need for rapid efficacious vaccines that could mitigate the impact of seasonal and future pandemics, multiple platforms are under development and/or investigation. What is clear is that any universal vaccine must provide long-lasting cross-protective immunity that can induce both B and T cell responses. This review will explore some of the universal influenza vaccine platforms in the contexts of their ability to induce long-lasting and cross-protective T cell immunity.
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Anticuerpos Antivirales/inmunología , Protección Cruzada , Vacunas contra la Influenza/inmunología , Gripe Humana/prevención & control , Orthomyxoviridae/inmunología , Animales , Ensayos Clínicos como Asunto , Humanos , Ratones , Infecciones por Orthomyxoviridae/inmunología , Linfocitos T/inmunología , VacunaciónRESUMEN
Despite causing pandemics and yearly epidemics that result in significant morbidity and mortality, our arsenal of options to treat influenza A virus (IAV) infections remains limited and is challenged by the virus itself. While vaccination is the preferred intervention strategy against influenza, its efficacy is reduced in the elderly and infants who are most susceptible to severe and/or fatal infections. In addition, antigenic variation of IAV complicates the production of efficacious vaccines. Similarly, effectiveness of currently used antiviral drugs is jeopardized by the development of resistance to these drugs. Like many viruses, IAV is reliant on host factors and signaling-pathways for its replication, which could potentially offer alternative options to treat infections. While host-factors have long been recognized as attractive therapeutic candidates against other viruses, only recently they have been targeted for development as IAV antivirals. Future strategies to combat IAV infections will most likely include approaches that alter host-virus interactions on the one hand or dampen harmful host immune responses on the other, with the use of biological response modifiers (BRMs). In principle, BRMs are biologically active agents including antibodies, small peptides, and/or other (small) molecules that can influence the immune response. BRMs are already being used in the clinic to treat malignancies and autoimmune diseases. Repurposing such agents would allow for accelerated use against severe and potentially fatal IAV infections. In this review, we will address the potential therapeutic use of different BRM classes to modulate the immune response induced after IAV infections.
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Factores Inmunológicos/farmacología , Factores Inmunológicos/uso terapéutico , Inmunomodulación/efectos de los fármacos , Virus de la Influenza A/efectos de los fármacos , Virus de la Influenza A/inmunología , Gripe Humana/tratamiento farmacológico , Gripe Humana/inmunología , Animales , Antivirales/química , Antivirales/farmacología , Antivirales/uso terapéutico , Interacciones Huésped-Patógeno/efectos de los fármacos , Interacciones Huésped-Patógeno/inmunología , Humanos , Factores Inmunológicos/química , Gripe Humana/metabolismo , Gripe Humana/virología , Resultado del TratamientoRESUMEN
Influenza A and B virus infections are a major cause of respiratory disease in humans and are responsible for substantial morbidity and mortality worldwide. Vaccination against influenza mainly aims at the induction of virus neutralizing serum antibodies, which are an important correlate of protection provided that the antibodies match the strains causing the outbreaks antigenically. In addition, virus-specific T cells are known to contribute to protective immunity to influenza virus infections by limiting duration and severity of the disease. As the majority of virus-specific T cells recognize epitopes located in relatively conserved proteins, like the Nucleoprotein and Matrix 1 protein, they display a high degree of cross-reactivity with a wide range of influenza viruses, including newly emerging viruses of alternative subtypes. Advancing our understanding of influenza virus-specific T cell responses and their role in protective immunity against influenza will aid the rational design of novel vaccines that could induce robust, broad and long-lasting immune responses. Here, we discuss the contribution of influenza virus-specific CD4+ and CD8+ T cells to protective immunity against influenza infection and the requirements and strategies for their induction by natural infection or vaccination, especially in children.
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Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Vacunas contra la Influenza/inmunología , Gripe Humana/inmunología , Orthomyxoviridae/inmunología , Diseño de Fármacos , Humanos , Inmunidad Celular , VacunaciónRESUMEN
Amiodarone interferes with the endocytic pathway, inhibits proteolysis, and causes the formation of vacuoles, but uptake and intracellular distribution of the drug, origin of vacuoles, and functional consequences of amiodarone accumulation remain unclear. Our objective was to study amiodarone uptake, clarify the origin of vacuoles, and investigate the effect of amiodarone on the life cycle of the coronavirus responsible for the Severe Acute Respiratory Syndrome (SARS), which, to enter cells, relies on the proteolytic cleavage of a viral spike protein by the endosomal proteinase cathepsin L. Using alveolar macrophages, we studied uptake of (125)I-amiodarone and (125)I-B2, an analog lacking the lateral group diethylamino-beta-ethoxy, and analyzed the effects of amiodarone on the distribution of endosomal markers and on the uptake of an acidotropic dye. Furthermore, using Vero cells, we tested the impact of amiodarone on the in vitro spreading of the SARS coronavirus. We found that (1) amiodarone associates with different cell membranes and accumulates in acidic organelles; (2) the diethylamino-beta-ethoxy group is an important determinant of uptake; (3) vacuoles forming upon exposure to amiodarone are enlarged late endosomes; (4) amiodarone inhibits the spreading in vitro of SARS coronavirus; and (5) trypsin cleavage of the viral spike protein before infection, which permits virus entry through the plasma membrane, does not impair amiodarone antiviral activity. We conclude that amiodarone alters late compartments of the endocytic pathway and inhibits SARS coronavirus infection by acting after the transit of the virus through endosomes.
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Amiodarona/farmacología , Antivirales/farmacología , Endosomas/metabolismo , Macrófagos Alveolares/metabolismo , Síndrome Respiratorio Agudo Grave/metabolismo , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/efectos de los fármacos , Amiodarona/farmacocinética , Animales , Antivirales/farmacocinética , Catepsina L , Catepsinas/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Chlorocebus aethiops , Cisteína Endopeptidasas/metabolismo , Citoplasma/efectos de los fármacos , Citoplasma/metabolismo , Endosomas/efectos de los fármacos , Humanos , Isótopos de Yodo/química , Macrófagos Alveolares/efectos de los fármacos , Macrófagos Alveolares/virología , Glicoproteínas de Membrana/metabolismo , Coronavirus Relacionado al Síndrome Respiratorio Agudo Severo/fisiología , Síndrome Respiratorio Agudo Grave/tratamiento farmacológico , Síndrome Respiratorio Agudo Grave/virología , Glicoproteína de la Espiga del Coronavirus , Vacuolas/efectos de los fármacos , Vacuolas/metabolismo , Células Vero , Proteínas del Envoltorio Viral/metabolismoRESUMEN
Currently used inactivated influenza vaccines aim at the induction of virus-neutralizing antibodies directed to the variable head domain of the viral hemagglutinin. Although these vaccines are effective against antigenically matching virus strains, they offer little protection against antigenically distinct drift variants or potentially pandemic viruses of alternative subtypes. In the last decades, the threat of novel influenza pandemics has sparked research efforts to develop vaccines that induce more broadly protective immunity. Here, we discuss the immune responses induced by conventional 'tailor-made' inactivated and live influenza vaccines and novel 'one fits all' candidate vaccines able to induce cross-reactive virus-specific antibody and T cell responses and to afford protection to a wider range of influenza viruses.
Asunto(s)
Vacunas contra la Influenza/inmunología , Gripe Humana/inmunología , Infecciones por Orthomyxoviridae/inmunología , Orthomyxoviridae/inmunología , Linfocitos T/inmunología , Animales , Anticuerpos Antivirales/metabolismo , Variación Antigénica , Reacciones Cruzadas , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Humanos , Inmunidad HeterólogaRESUMEN
Developing countries are burdened with Shigella diarrhea. Understanding mucosal immune responses associated with natural Shigella infection is important to identify potential correlates of protection and, as such, to design effective vaccines. We performed a comparative analysis of circulating mucosal plasmablasts producing specific antibodies against highly conserved invasive plasmid antigens (IpaC, IpaD20, and IpaD120) and two recently identified surface protein antigens, pan-Shigella surface protein antigen 1 (PSSP1) and PSSP2, common to all virulent Shigella strains. We examined blood and stool specimens from 37 diarrheal patients admitted to the Infectious Diseases & Beliaghata General Hospital, Kolkata, India. The etiological agent of diarrhea was investigated in stool specimens by microbiological methods and real-time PCR. Gut-homing (α4ß7 (+)) antibody-secreting cells (ASCs) were isolated from patient blood by means of combined magnetic cell sorting and two-color enzyme-linked immunosorbent spot (ELISPOT) assay. Overall, 57% (21 of 37) and 65% (24 of 37) of the patients were positive for Shigella infection by microbiological and real-time PCR assays, respectively. The frequency of α4ß7 (+) IgG ASC responders against Ipas was higher than that observed against PSSP1 or PSSP2, regardless of the Shigella serotype isolated from these patients. Thus, α4ß7 (+) ASC responses to Ipas may be considered an indirect marker of Shigella infection. The apparent weakness of ASC responses to PSSP1 is consistent with the lack of cross-protection induced by natural Shigella infection. The finding that ASC responses to IpaD develop in patients with recent-onset shigellosis indicates that such responses may not be protective or may wane too rapidly and/or be of insufficient magnitude.
Asunto(s)
Anticuerpos Antibacterianos/inmunología , Antígenos Bacterianos/inmunología , Diarrea/patología , Disentería Bacilar/patología , Proteínas de la Membrana/inmunología , Células Plasmáticas/inmunología , Shigella/inmunología , Adolescente , Adulto , Anciano , Células Productoras de Anticuerpos/inmunología , Femenino , Hospitalización , Humanos , Inmunofenotipificación , India , Integrinas/análisis , Masculino , Persona de Mediana Edad , Células Plasmáticas/química , Adulto JovenRESUMEN
BACKGROUND: The "gold standard" for assessing mucosal immunity after vaccination with poliovirus vaccines consists in measuring virus excretion in stool after challenge with oral poliovirus vaccine (OPV). This testing is time and resource intensive, and development of alternative methods is a priority for accelerating polio eradication. We therefore evaluated circulating antibody-secreting cells (ASCs) as a potential means to evaluate mucosal immunity to poliovirus vaccine. METHODS: 199 subjects, aged 10 years, and previously immunized repeatedly with OPV, were selected. Subjects were assigned to receive either a booster dose of inactivated poliovirus vaccine (IPV), bivalent OPV (bOPV), or no vaccine. Using a micro-modified whole blood-based ELISPOT assay designed for field setting, circulating poliovirus type-specific IgA- and IgG-ASCs, including gut homing α4ß7+ ASCs, were enumerated on days 0 and 7 after booster immunization. In addition, serum samples collected on days 0, 28 and 56 were tested for neutralizing antibody titers against poliovirus types 1, 2, and 3. Stool specimens were collected on day 28 (day of bOPV challenge), and on days 31, 35 and 42 and processed for poliovirus isolation. RESULTS: An IPV dose elicited blood IgA- and IgG-ASC responses in 84.8 to 94.9% of subjects, respectively. In comparison, a bOPV dose evoked corresponding blood ASC responses in 20.0 to 48.6% of subjects. A significant association was found between IgA- and IgG-ASC responses and serum neutralizing antibody titers for poliovirus type 1, 2, 3 (p<0.001). In the IPV group, α4ß7+ ASCs accounted for a substantial proportion of IgA-ASCs and the proportion of subjects with a positive α4ß7+ IgA-ASC response to poliovirus types 1, 2 and 3 was 62.7%, 89.8% and 45.8%, respectively. A significant association was observed between virus excretion and α4ß7+ IgA- and/or IgG-ASC responses to poliovirus type 3 among immunized children; however, only a weak association was found for type 1 poliovirus. DISCUSSION: Our results suggest that virus-specific blood ASCs, especially for type 3 poliovirus, can serve as surrogate of mucosal immunity after vaccination. Further studies are needed to evaluate the duration of such memory responses and to assess the programmatic utility of this whole blood-based mucosal ASC testing for the polio eradication program.