Remdesivir efficacy against yellow fever in a hamster model.

Yellow fever virus (YFV) continues to cause periodic outbreaks of severe disease throughout tropical regions of South America and Africa despite the availability of an effective vaccine. Despite efforts to control this virus for the last century, no antivirals have been approved for the treatment of YFV. The purpose of this study was to evaluate the broadly active antiviral compound remdesivir (RDV) in a hamster model of disease. Yellow fever (YF) disease in hamsters was prevented when treatment with RDV was initiated just prior to virus challenge, which was confirmed in a second study. Disease parameters including viremia, serum ALT and weight loss were significantly improved with RDV treatment in a dose-dependent manner. RDV was also effective when treatment was initiated as late as 4 days post-virus infection (dpi). These results demonstrate therapeutic efficacy of RDV in the treatment of YF in a relevant animal model of disease.

Repurposing the yellow fever vaccine for intratumoral immunotherapy.

Live 17D is widely used as a prophylactic vaccine strain for yellow fever virus that induces potent neutralizing humoral and cellular immunity against the wild-type pathogen. 17D replicates and kills mouse and human tumor cell lines but not non-transformed human cells. Intratumoral injections with viable 17D markedly delay transplanted tumor progression in a CD8 T-cell-dependent manner. In mice bearing bilateral tumors in which only one is intratumorally injected, contralateral therapeutic effects are observed consistent with more prominent CD8 T-cell infiltrates and a treatment-related reduction of Tregs. Additive efficacy effects were observed upon co-treatment with intratumoral 17D and systemic anti-CD137 and anti-PD-1 immunostimulatory monoclonal antibodies. Importantly, when mice were preimmunized with 17D, intratumoral 17D treatment achieved better local and distant antitumor immunity. Such beneficial effects of prevaccination are in part explained by the potentiation of CD4 and CD8 T-cell infiltration in the treated tumor. The repurposed use of a GMP-grade vaccine to be given via the intratumoral route in prevaccinated patients constitutes a clinically feasible and safe immunotherapy approach.

Análise das características epidemiológicas da febre amarela em um estado da Região Sudeste do Brasil / Análisis de las características epidemiológicas de la fiebre amarilla en un estado del sureste de Brasil / Analysis of the epidemiological characteristics of yellow fever in a state of southeastern Brazil

Resumo O objetivo do estudo foi analisar o perfil epidemiológico da febre amarela (FA) em Minas Gerais, região sudeste do Brasil. Trata-se de estudo transversal, do tipo série de casos, analisando as notificações de FA entre 03 de janeiro de 2016 a 08 de julho de 2017. Foram notificados 1.677 casos, sendo 427 confirmados e 133 óbitos; com taxa de letalidade de 31,3%. A maioria dos casos foi em homens, adultos jovens, ocupação rural e baixa escolaridade. Em 2016, 28 municípios notificaram epizootias e 1 confirmou morte de macaco por FA. Em 2017, 182 municípios notificaram e 142 confirmaram. No período analisado, a cobertura vacinal média foi inferior a 90% em 96% das Unidades Regionais de Saúde. Destacam-se elevadas porcentagens de campos não preenchidos. Constatou-se elevado número de casos no período analisado. Considerar o perfil epidemiológico da doença no Estado é importante para direcionar as ações de controle, movendo esforços para os grupos mais vulneráveis.

Resumen El objetivo de este estudio fue analizar el perfil epidemiológico de la fiebre amarilla (FA) en Minas Gerais, sureste de Brasil. Se planteó un estudio transversal, de tipo serie de casos, con análisis de las notificaciones entre 03 de enero de 2016 a 08 de julio de 2017. Se notificaron 1.677 casos, siendo 427 confirmados y 133 muertos; con tasa de letalidad de 31,3%. Ocurrió más en hombres jóvenes, con ocupación rural y baja educación. En 2016, 28 municipios tienen epizootias y fue confirmada una muerte de mono por FA. En 2017, se han notificado a 182 municipios y 142 confirmados. La cobertura de vacunación promedio fue inferior al 90% en 96% de las Unidades Regionales de Salud. Incluyen altos porcentajes de campos sin llenar. Tiene alto número de casos en el período analizado. Se concluye que es importante considerar el perfil epidemiológico de la enfermedad en el estado para dirigir las acciones de control, hacia los grupos más vulnerables.

Abstract The objective of this study was to analyze the epidemiological profile of yellow fever (YF) in Minas Gerais, southeastern Brazil. A cross-sectional study was raised, of type series of cases, with analysis of the notifications of between January 03, 2016 to July 08, 2017. 1,677 cases were reported, with 427 confirmed and 133 dead; with a lethality rate of 31,3%. It happened more in young men, rural occupation and low education. In 2016, 28 municipalities have epizootics and one confirmed death of monkey by YF. In 2017, 182 municipalities have notified and 142 confirmed. In the analysis period, the average vaccination coverage was less than 90% in 96% of Regional Health Units. High percentages of unfilled fields were found. It has a high number of cases in the period analyzed. It is concluded that it is important to consider the epidemiological profile of the disease in the State is important to direct the actions of control, moving efforts to the most vulnerable groups.

Plant-Produced Subunit Vaccine Candidates against Yellow Fever Induce Virus Neutralizing Antibodies and Confer Protection against Viral Challenge in Animal Models.

Yellow fever (YF) is a viral disease transmitted by mosquitoes and endemic mostly in South America and Africa with 20-50% fatality. All current licensed YF vaccines, including YF-Vax® (Sanofi-Pasteur, Lyon, France) and 17DD-YFV (Bio-Manguinhos, Rio de Janeiro, Brazil), are based on live attenuated virus produced in hens' eggs and have been widely used. The YF vaccines are considered safe and highly effective. However, a recent increase in demand for YF vaccines and reports of rare cases of YF vaccine-associated fatal adverse events have provoked interest in developing a safer YF vaccine that can be easily scaled up to meet this increased global demand. To this point, we have engineered the YF virus envelope protein (YFE) and transiently expressed it in Nicotiana benthamiana as a stand-alone protein (YFE) or as fusion to the bacterial enzyme lichenase (YFE-LicKM). Immunogenicity and challenge studies in mice demonstrated that both YFE and YFE-LicKM elicited virus neutralizing (VN) antibodies and protected over 70% of mice from lethal challenge infection. Furthermore, these two YFE-based vaccine candidates induced VN antibody responses with high serum avidity in nonhuman primates and these VN antibody responses were further enhanced after challenge infection with the 17DD strain of YF virus. These results demonstrate partial protective efficacy in mice of YFE-based subunit vaccines expressed in N. benthamiana. However, their efficacy is inferior to that of the live attenuated 17DD vaccine, indicating that formulation development, such as incorporating a more suitable adjuvant, may be required for product development.

Human endogenous retroviruses and cancer prevention: evidence and prospects.

BACKGROUND: Cancer is a significant and growing problem worldwide. While this increase may, in part, be attributed to increasing longevity, improved case notifications and risk-enhancing lifestyle (such as smoking, diet and obesity), hygiene-related factors resulting in immuno-regulatory failure may also play a major role and call for a revision of vaccination strategies to protect against a range of cancers in addition to infections. DISCUSSION: Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitutes part of the human genome. They were originated by the integration of exogenous retroviruses into the human genome millions of years ago. HERVs are estimated to comprise about 8% of human DNA and are ubiquitous in somatic and germinal tissues.Physiologic and pathologic processes are influenced by some biologically active HERV families. HERV antigens are only expressed at low levels by the host, but in circumstances of inappropriate control their genes may initiate or maintain pathological processes. Although the precise mechanism leading to abnormal HERVs gene expression has yet to be clearly elucidated, environmental factors seem to be involved by influencing the human immune system.HERV-K expression has been detected in different types of tumors.Among the various human endogenous retroviral families, the K series was the latest acquired by the human species. Probably because of its relatively recent origin, the HERV-K is the most complete and biologically active family.The abnormal expression of HERV-K seemingly triggers pathological processes leading to melanoma onset, but also contributes to the morphological and functional cellular modifications implicated in melanoma maintenance and progression.The HERV-K-MEL antigen is encoded by a pseudo-gene incorporated in the HERV-K env-gene. HERV-K-MEL is significantly expressed in the majority of dysplastic and normal naevi, as well as other tumors like sarcoma, lymphoma, bladder and breast cancer. An amino acid sequence similar to HERV-K-MEL, recognized to cause a significant protective effect against melanoma, is shared by the antigenic determinants expressed by some vaccines such as BCG, vaccinia virus and the yellow fever virus.HERV-K are also reactivated in the majority of human breast cancers. Monoclonal and single-chain antibodies against the HERV-K Env protein recently proved capable of blocking the proliferation of human breast cancer cells in vitro, inhibiting tumor growth in mice bearing xenograft tumors. SUMMARY: A recent epidemiological study provided provisional evidence of how melanoma risk could possibly be reduced if the yellow fever virus vaccine (YFV) were received at least 10 years before, possibly preventing tumor initiation rather than culling melanoma cells already compromised. Further research is recommended to confirm the temporal pattern of this protection and eliminate/attenuate the potential role of relevant confounders as socio-economic status and other vaccinations.It appears also appropriate to examine the potential protective effect of YFV against other malignancies expressing high levels of HERV-K antigens, namely breast cancer, sarcoma, lymphoma and bladder cancer.Tumor immune-therapy, as described for the monoclonal antibodies against breast cancer, is indeed considered more complex and less advantageous than immune-prevention. Cellular immunity possibly triggered by vaccines as for YFV might also be involved in anti-cancer response, in addition to humoral immunity.

Pre-clinical efficacy and safety of experimental vaccines based on non-replicating vaccinia vectors against yellow fever.

BACKGROUND: Currently existing yellow fever (YF) vaccines are based on the live attenuated yellow fever virus 17D strain (YFV-17D). Although, a good safety profile was historically attributed to the 17D vaccine, serious adverse events have been reported, making the development of a safer, more modern vaccine desirable. METHODOLOGY/PRINCIPAL FINDINGS: A gene encoding the precursor of the membrane and envelope (prME) protein of the YFV-17D strain was inserted into the non-replicating modified vaccinia virus Ankara and into the D4R-defective vaccinia virus. Candidate vaccines based on the recombinant vaccinia viruses were assessed for immunogenicity and protection in a mouse model and compared to the commercial YFV-17D vaccine. The recombinant live vaccines induced γ-interferon-secreting CD4- and functionally active CD8-T cells, and conferred full protection against lethal challenge already after a single low immunization dose of 10(5) TCID(50). Surprisingly, pre-existing immunity against wild-type vaccinia virus did not negatively influence protection. Unlike the classical 17D vaccine, the vaccinia virus-based vaccines did not cause mortality following intracerebral administration in mice, demonstrating better safety profiles. CONCLUSIONS/SIGNIFICANCE: The non-replicating recombinant YF candidate live vaccines induced a broad immune response after single dose administration, were effective even in the presence of a pre-existing immunity against vaccinia virus and demonstrated an excellent safety profile in mice.

Can prior vaccinations against certain infections confer protection against developing melanoma?

Currently available, relatively safe vaccines may help tackle this serious and increasing public health problem.

Systems biology approach predicts immunogenicity of the yellow fever vaccine in humans.

A major challenge in vaccinology is to prospectively determine vaccine efficacy. Here we have used a systems biology approach to identify early gene 'signatures' that predicted immune responses in humans vaccinated with yellow fever vaccine YF-17D. Vaccination induced genes that regulate virus innate sensing and type I interferon production. Computational analyses identified a gene signature, including complement protein C1qB and eukaryotic translation initiation factor 2 alpha kinase 4-an orchestrator of the integrated stress response-that correlated with and predicted YF-17D CD8(+) T cell responses with up to 90% accuracy in an independent, blinded trial. A distinct signature, including B cell growth factor TNFRS17, predicted the neutralizing antibody response with up to 100% accuracy. These data highlight the utility of systems biology approaches in predicting vaccine efficacy.

[Antiviral immunization of immunocompromised adults, literature review]. / Vaccination antivirale des adultes immunodéprimés, revue de la littérature.

PURPOSE: Immunization, by preventing infections, has a major interest for the immunocompromised subjects. The aim of this article is to make a point on data concerning efficacy (in terms of immunogenicity) and safety of viral vaccines available in France and to synthesize existing guidelines for four groups of patients: solid organ and hematopoietic stem cell transplant recipients, HIV infected persons and patients treated by immunosuppressive drugs for a systemic disease. CURRENT KNOWLEDGE AND KEY POINTS: Available data about vaccines immunogenicity and safety for immunocompromised adults are rare. However, those data indicate that, when immunization contraindications and recommendations are applied, vaccines remain well tolerated and most of the time immunogenic, even if the percentage of responders is lower compared to non immunocompromised persons. Still, the specific guidelines that have been elaborated for immunization of immunocompromised adults are imprecise and incomplete, emphasizing a lack of data about this topic. FUTURE PROSPECTS: Clinical studies remain necessary to precise vaccines immunogenicity and safety for immunocompromised adults. In the meantime, a harmonization of immunization practices for immunocompromised adults should be proposed, so as to help practitioners to succeed a better immunization coverage for these patients.

Comparative safety and immunogenicity of two yellow fever 17D vaccines (ARILVAX and YF-VAX) in a phase III multicenter, double-blind clinical trial.

Yellow fever (YF) is a significant health problem in South America and Africa. Travelers to these areas require immunization. The United States, infested with Aedes aegypti mosquitoes, is at risk of introduction of this disease. There is only a single U.S. manufacturer of YF 17D vaccine, and supplies may be insufficient in an emergency. A randomized, double-blind outpatient study was conducted in 1,440 healthy individuals, half of whom received the U.S. vaccine (YF-VAX) and half the vaccine manufactured in the United Kingdom (ARILVAX). A randomly selected subset of approximately 310 individuals in each treatment group was tested for YF neutralizing antibodies 30 days after vaccination. The primary efficacy endpoint was the proportion of individuals who developed a log neutralization index (LNI) of 0.7 or higher. Seroconversion occurred in 98.6% of individuals in the ARILVAX group and 99.3% of those in the YF-VAX group. Statistically, ARILVAX was equivalent to YF-VAX (P = .001). Both vaccines elicited mean antibody responses well above the minimal level (LNI 0.7) protective against wild-type YF virus. The mean LNI in the YF-VAX group was higher (2.21) than in the ARILVAX group (2.06; P = .010) possibly because of the higher dose contained in YF-VAX. Male gender, Caucasian race, and smoking were associated with higher antibody responses. Both vaccines were well tolerated. Overall, the treatment groups were comparable with respect to safety except that individuals in the ARILVAX group experienced significantly less edema, inflammation, and pain at the injection site than those in the YF-VAX group. No serious adverse events were attributable to either vaccine. YF-VAX participants (71.9%) experienced one or more nonserious adverse events than ARILVAX individuals (65.3%; P = .008). The difference was due to a higher rate of injection site reactions in the YF-VAX group. Mild systemic reactions (headache, myalgia, malaise, asthenia) occurred in roughly 10% to 30% of participants during the first few days after vaccination, with no significant difference across treatment groups. Adverse events were less frequent in individuals with preexisting immunity to YF, indicating a relationship to virus replication.