Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes global epidemics of a debilitating polyarthritis in humans. As there is a pressing need for the development of therapeutic ...agents, we screened 230 new mouse anti-CHIKV monoclonal antibodies (MAbs) for their ability to inhibit infection of all three CHIKV genotypes. Four of 36 neutralizing MAbs (CHK-102, CHK-152, CHK-166, and CHK-263) provided complete protection against lethality as prophylaxis in highly susceptible immunocompromised mice lacking the type I IFN receptor (Ifnar(-/-) ) and mapped to distinct epitopes on the E1 and E2 structural proteins. CHK-152, the most protective MAb, was humanized, shown to block viral fusion, and require Fc effector function for optimal activity in vivo. In post-exposure therapeutic trials, administration of a single dose of a combination of two neutralizing MAbs (CHK-102+CHK-152 or CHK-166+CHK-152) limited the development of resistance and protected immunocompromised mice against disease when given 24 to 36 hours before CHIKV-induced death. Selected pairs of highly neutralizing MAbs may be a promising treatment option for CHIKV in humans.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Zika virus (ZIKV) has gained worldwide attention since it emerged, and a global effort is underway to understand the correlates of protection and develop diagnostics to identify rates of infection. ...As new therapeutics and vaccine approaches are evaluated in clinical trials, additional effort is focused on identifying the adaptive immune correlates of protection against ZIKV disease. To aid in this endeavor we have begun to dissect the role of CD4+T cells in the protection against neuroinvasive ZIKV disease. We have identified an important role for CD4+T cells in protection, demonstrating that in the absence of CD4+T cells mice have more severe neurological sequela and significant increases in viral titers in the central nervous system (CNS). The transfer of CD4+T cells from ZIKV immune mice protect type I interferon receptor deficient animals from a lethal challenge; showing that the CD4+T cell response is necessary and sufficient for control of ZIKV disease. Using a peptide library spanning the complete ZIKV polyprotein, we identified both ZIKV-encoded CD4+T cell epitopes that initiate immune responses, and ZIKV specific CD4+T cell receptors that recognize these epitopes. Within the ZIKV antigen-specific TCRβ repertoire, we uncovered a high degree of diversity both in response to a single epitope and among different mice responding to a CD4+T cell epitope. Overall this study identifies a novel role for polyfunctional and polyclonal CD4+T cells in providing protection against ZIKV infection and highlights the need for vaccines to develop robust CD4+T cell responses to prevent ZIKV neuroinvasion and limit replication within the CNS.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Chikungunya virus (CHIKV) is a mosquito-transmitted RNA virus that causes acute febrile infection associated with polyarthralgia in humans. Mechanisms of protective immunity against CHIKV are poorly ...understood, and no effective therapeutics or vaccines are available. We isolated and characterized human monoclonal antibodies (mAbs) that neutralize CHIKV infectivity. Among the 30 mAbs isolated, 13 had broad and ultrapotent neutralizing activity (IC50 < 10 ng/ml), and all of these mapped to domain A of the E2 envelope protein. Potent inhibitory mAbs blocked post-attachment steps required for CHIKV membrane fusion, and several were protective in a lethal challenge model in immunocompromised mice, even when administered at late time points after infection. These highly protective mAbs could be considered for prevention or treatment of CHIKV infection, and their epitope location in domain A of E2 could be targeted for rational structure-based vaccine development.
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•A panel of 30 chikungunya virus-specific antibodies (Abs) isolated from a single donor•13 Abs exhibited broad and potent neutralizing activity with IC50 < 10 ng/ml•Potently neutralizing Abs bind to the E2 envelope protein and block viral fusion•Several Abs exhibited prophylactic and therapeutic activity in a mouse model
No effective therapy or vaccine is available for chikungunya virus (CHIKV), a debilitating mosquito-borne pathogen that is spreading globally. Smith et al. isolated and characterized a panel of broad and potent CHIKV-specific human monoclonal antibodies. Several antibodies exhibited prophylactic and therapeutic activity in mice and their mechanism suggests vaccine approaches.
Zika virus (ZIKV) is a re-emerging virus that has recently spread into dengue virus (DENV) endemic regions and cross-reactive antibodies (Abs) could potentially affect ZIKV pathogenesis. Using ...DENV-immune serum, it has been shown in vitro that antibody-dependent enhancement (ADE) of ZIKV infection can occur. Here we study the effects of pre-existing DENV immunity on ZIKV infection in vivo. We infect two cohorts of rhesus macaques with ZIKV; one cohort has been exposed to DENV 2.8 years earlier and a second control cohort is naïve to flaviviral infection. Our results, while confirming ADE in vitro, suggest that pre-existing DENV immunity does not result in more severe ZIKV disease. Rather our results show a reduction in the number of days of ZIKV viremia compared to naïve macaques and that the previous exposure to DENV may result in modulation of the immune response without resulting in enhancement of ZIKV pathogenesis.
Both the SARS-CoV-2 pandemic and emergence of variants of concern have highlighted the need for functional antibody assays to monitor the humoral response over time. Antibodies directed against the ...spike (S) protein of SARS-CoV-2 are an important component of the neutralizing antibody response. In this work, we report that in a subset of patients-despite a decline in total S-specific antibodies-neutralizing antibody titers remain at a similar level for an average of 98 days in longitudinal sampling of a cohort of 59 Hispanic/Latino patients exposed to SARS-CoV-2. Our data suggest that 100% of seroconverting patients make detectable neutralizing antibody responses which can be quantified by a surrogate viral neutralization test. Examination of sera from ten out of the 59 subjects which received mRNA-based vaccination revealed that both IgG titers and neutralizing activity of sera were higher after vaccination compared to a cohort of 21 SARS-CoV-2 naïve subjects. One dose was sufficient for the induction of a neutralizing antibody, but two doses were necessary to reach 100% surrogate virus neutralization in subjects irrespective of previous SARS-CoV-2 natural infection status. Like the pattern observed after natural infection, the total anti-S antibodies titers declined after the second vaccine dose; however, neutralizing activity remained relatively constant for more than 80 days after the first vaccine dose. Furthermore, our data indicates that-compared with mRNA vaccination-natural infection induces a more robust humoral immune response in unexposed subjects. This work is an important contribution to understanding the natural immune response to the novel coronavirus in a population severely impacted by SARS-CoV-2. Furthermore, by comparing the dynamics of the immune response after the natural infection vs. the vaccination, these findings suggest that functional neutralizing antibody tests are more relevant indicators than the presence or absence of binding antibodies.
Prominent immune alterations associated with aging include the loss of naïve T-cell numbers, diversity and function. While genetic contributors and mechanistic details in the aging process have been ...addressed in multiple studies, the role of environmental agents in immune aging remains incompletely understood. From the standpoint of environmental infectious agents, latent cytomegalovirus (CMV) infection has been associated with an immune risk profile in the elderly humans, yet the cause-effect relationship of this association remains unclear. Here we present direct experimental evidence that mouse CMV (MCMV) infection results in select T-cell subset changes associated with immune aging, namely the increase of relative and absolute counts of CD8 T-cells in the blood, with a decreased representation of the naïve and the increased representation of the effector memory blood CD8 T-cells. Moreover, MCMV infection resulted in significantly weaker CD8 responses to superinfection with Influenza, Human Herpes Virus I or West-Nile-Virus, even 16 months following MCMV infection. These irreversible losses in T-cell function could not be observed in uninfected or in vaccinia virus-infected controls and were not due to the immune-evasive action of MCMV genes. Rather, the CD8 activation in draining lymph nodes upon viral challenge was decreased in MCMV infected mice and the immune response correlated directly to the frequency of the naïve and inversely to that of the effector cells in the blood CD8 pool. Therefore, latent MCMV infection resulted in pronounced changes of the T-cell compartment consistent with impaired naïve T-cell function.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Many flaviviruses including dengue (DENV), and Zika (ZIKV) have attracted significant attention in the past few years. As many flaviviruses are spread by arthropods, most of the world's population is ...at risk of encountering a flavivirus, and infection with these viruses has created a significant disease burden worldwide. Vaccination against flaviviruses is thought to be one of the most promising avenues for reducing the disease burden associated with these viruses. The optimism surrounding a vaccine approach is supported by the highly successful vaccines for yellow fever and Japanese encephalitis. Central to the development of new successful vaccines is the understanding of the correlates of protection that will be necessary to engineer into new vaccines. To aid in this endeavor we have directed our efforts to identify correlates of protection that will reduce the disease burden associated with ZIKV and DENV. Within this study we have identified a novel murine ZIKV specific CD8
T cell epitope, and shown that the ZIKV epitope specific CD8
T cell response has a distinct immunodominance hierarchy present during acute infection and is detectible as part of the memory T cell responses. Our studies confirm that ZIKV-specific CD8
T cells are an important correlate of protection for ZIKV and demonstrate that both naïve and ZIKV immune CD8
T cells are sufficient for protection against a lethal ZIKV infection. Overall this study adds to the body of literature demonstrating a role for CD8
T cells in controlling flavivirus infection.
The novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic. Critical to the rapid evaluation of vaccines and antivirals against SARS-CoV-2 is the ...development of tractable animal models to understand the adaptive immune response to the virus. To this end, the use of common laboratory strains of mice is hindered by significant divergence of the angiotensin-converting enzyme 2 (ACE2), which is the receptor required for entry of SARS-CoV-2. In the current study, we designed and utilized an mRNA-based transfection system to induce expression of the hACE2 receptor in order to confer entry of SARS-CoV-2 in otherwise non-permissive cells. By employing this expression system in an in vivo setting, we were able to interrogate the adaptive immune response to SARS-CoV-2 in type 1 interferon receptor deficient mice. In doing so, we showed that the T cell response to SARS-CoV-2 is enhanced when hACE2 is expressed during infection. Moreover, we demonstrated that these responses are preserved in memory and are boosted upon secondary infection. Importantly, using this system, we functionally identified the CD4+ and CD8+ structural peptide epitopes targeted during SARS-CoV-2 infection in H2b restricted mice and confirmed their existence in an established model of SARS-CoV-2 pathogenesis. We demonstrated that, identical to what has been seen in humans, the antigen-specific CD8+ T cells in mice primarily target peptides of the spike and membrane proteins, while the antigen-specific CD4+ T cells target peptides of the nucleocapsid, membrane, and spike proteins. As the focus of the immune response in mice is highly similar to that of the humans, the identification of functional murine SARS-CoV-2-specific T cell epitopes provided in this study will be critical for evaluation of vaccine efficacy in murine models of SARS-CoV-2 infection.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dengue virus (DENV) is the most common vector-borne viral disease, with nearly 400 million worldwide infections each year concentrated in the tropical and subtropical regions of the world. Severe ...dengue complications are often associated with a secondary heterotypic infection of one of the four circulating serotypes. In this scenario, humoral immune responses targeting cross-reactive, poorly neutralizing epitopes can lead to increased infectivity of susceptible cells via antibody-dependent enhancement (ADE). In this way, antibodies produced in response to infection or vaccination are capable of contributing to enhanced disease in subsequent infections. Currently, there are no available therapeutics to combat DENV disease, and there is an urgent need for a safe and efficacious vaccine. Here, we developed a nucleotide-modified mRNA vaccine encoding the membrane and envelope structural proteins from DENV serotype 1 encapsulated in lipid nanoparticles (prM/E mRNA-LNP). Vaccination of mice elicited robust antiviral immune responses comparable to viral infection, with high levels of neutralizing antibody titers and antiviral CD4
and CD8
T cells. Immunocompromised AG129 mice vaccinated with the prM/E mRNA-LNP vaccine were protected from a lethal DENV challenge. Vaccination with either a wild-type vaccine or a vaccine with mutations in the immunodominant fusion loop epitope elicited equivalent humoral and cell-mediated immune responses. Neutralizing antibodies elicited by the vaccine were sufficient to protect against a lethal challenge. Both vaccine constructs demonstrated serotype-specific immunity with minimal serum cross-reactivity and reduced ADE in comparison to a live DENV1 viral infection.
With 400 million worldwide infections each year, dengue is the most common vector-borne viral disease. Forty percent of the world's population is at risk, with dengue experiencing consistent geographic spread over the years. With no therapeutics available and vaccines performing suboptimally, the need for an effective dengue vaccine is urgent. Here, we develop and characterize a novel mRNA vaccine encoding the dengue serotype 1 envelope and premembrane structural proteins that is delivered via a lipid nanoparticle. Our DENV1 prM/E mRNA-LNP vaccine induces neutralizing antibody and cellular immune responses in immunocompetent mice and protects an immunocompromised mouse from a lethal DENV challenge. Existing antibodies against dengue can enhance subsequent infections via antibody-dependent enhancement (ADE). Importantly our vaccine induced only serotype-specific immune responses and did not induce ADE.
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