Comparison of lyophilized versus liquid modified vaccinia Ankara (MVA) formulations and subcutaneous versus intradermal routes of administration in healthy vaccinia-naïve subjects

An Ulcer by Any Other Name

The myriad presentations of ulcerative sexually transmitted infections, other than genital herpes and syphilis, challenge even the most astute clinician given the considerable overlap in clinical presentation and lack of widely available diagnostic resources, such as nucleic acid testing, to confirm the diagnosis. Even so, case prevalence is relatively low, and incidence of chancroid and granuloma inguinale are declining. These diseases still cause substantial morbidity and increased chance for HIV acquisition, and with the recent advent of mpox as a cause, it remains imperative to identify and treat accurately.

A randomized phase 3 trial to assess the immunogenicity and safety of 3 consecutively produced lots of freeze-dried MVA-BN® vaccine in healthy adults

Since vaccination remains the only effective protection against orthopox virus-induced diseases such as smallpox or monkeypox, the strategic use and stockpiling of these vaccines remains of significant public health importance. The approved liquid-frozen formulation of Bavarian Nordic's Modified Vaccinia Ankara (MVA-BN) smallpox vaccine has specific cold-chain requirements, while the freeze-dried (FD) formulation of this vaccine provides more flexibility in terms of storage conditions and shelf life. In this randomized phase 3 trial, the immunogenicity and safety of 3 consecutively manufactured lots of the FD MVA-BN vaccine was evaluated. A total of 1129 healthy adults were randomized to 3 treatment groups (lots 1 to 3) and received 2 vaccinations 4 weeks apart. For both neutralizing and total antibodies, a robust increase of geometric mean titer (GMT) was observed across all lot groups 2 weeks following the second vaccination, comparable to published data. For the primary results, the ratios of the neutralizing antibody GMTs between the lot group pairs ranged from 0.936 to 1.115, with confidence ratios well within the pre-specified margin of equivalence. Results for total antibodies were similar. In addition, seroconversion rates were high across the 3 lots, ranging between 99.1 % and 99.7 %. No safety concerns were identified; particularly, no inflammatory cardiac disorders were detected. The most common local solicited adverse events (AEs) reported across lot groups were injection site pain (87.2%) and erythema (73.2%), while the most common general solicited adverse events were myalgia, fatigue, and headache in 40.6% to 45.5% of all participants, with no meaningful differences among the lot groups. No related serious AEs were reported. In conclusion, the data demonstrate consistent and robust immunogenicity and safety results with a freeze-dried formulation of MVA-BN. Clinical Trial Registry Number: NCT03699124.

Monkeypox

Monkeypox is a zoonotic illness caused by the monkeypox virus, an Orthopoxvirus in the same genus as the variola, vaccinia, and cowpox viruses. Since the detection of the first human case in the Democratic Republic of the Congo in 1970, the disease has caused sporadic infections and outbreaks, mainly restricted to some countries in west and central Africa. In July, 2022, WHO declared monkeypox a Public Health Emergency of International Concern, on account of the unprecedented global spread of the disease outside previously endemic countries in Africa and the need for global solidarity to address this previously neglected disease. The 2022 outbreak has been primarily associated with close intimate contact (including sexual activity) and most cases have been diagnosed among men who have sex with men, who often present with novel epidemiological and clinical characteristics. In the 2022 outbreak, the incubation period ranges from 7 days to 10 days and most patients present with a systemic illness that includes fever and myalgia and a characteristic rash, with papules that evolve to vesicles, pustules, and crusts in the genital, anal, or oral regions and often involve the mucosa. Complications that require medical treatment (eg, antiviral therapy, antibacterials, and pain control) occur in up to 40% of patients and include rectal pain, odynophagia, penile oedema, and skin and anorectal abscesses. Most patients have a self-limited illness; between 1% and 13% require hospital admission (for treatment or isolation), and the case-fatality rate is less than 0·1%. A diagnosis can be made through the presence of Orthopoxvirus DNA in PCRs from lesion swabs or body fluids. Patients with severe manifestations and people at risk of severe disease (eg, immunosuppressed people) could benefit from antiviral treatment (eg, tecovirimat). The current strategy for post-exposure prophylaxis or pre-exposure prophylaxis for people at high risk is vaccination with the non-replicating modified vaccinia Ankara. Antiviral treatment and vaccines are not yet available in endemic countries in Africa.

Safety and immunogenicity of orally administered poxvirus vectored constructs in the white-footed mouse (Peromyscus leucopus)

Globally, zoonotic spillover is becoming more frequent and represents a growing public health concern. Reservoir-targeted vaccination offers an intriguing alternative to traditional vaccine practices by establishing protection in wild populations that maintain the natural pathogen cycle. As an important pathogen reservoir, Peromyscus leucopus Rafinesque or the white-footed mouse has been the target of several experimental vaccines. However, strategies are limited by the method of administration, need for repeated dosing, or safety of constructs in the field. To address these concerns, we evaluated two highly attenuated poxviruses, raccoonpox virus (RCN) and modified vaccinia Ankara (MVA) virus as potential oral vaccine vectors in white-footed mice. Following oral administration, P. leucopus showed no adverse signs. A single oral dose elicited robust immune responses in mice to the foreign influenza hemagglutinin protein expressed by poxvirus vaccine vectors. Serum hemagglutinin inhibition antibody titers were detected by day 7 post immunization and persisted until study termination (77 days post immunization). This study establishes the safety and immunogenicity of recombinant MVA and RCN poxviruses in P. leucopus and demonstrates the suitability of these vectors as part of a reservoir-targeted vaccine strategy for white-footed mice.

The Potential Role of Passive Antibody-Based Therapies as Treatments for Monkeypox

Monkeypox, a zoonosis caused by the orthopox monkeypox virus (MPXV) that is endemic to Central and West Africa, was previously linked to sporadic outbreaks and rare, travel-associated cases. An outbreak of monkeypox in 2022 has spurred a public health emergency of international concern, and this outbreak is unprecedented in terms of its scale and epidemiology. The outbreak has been focused overwhelmingly in men who have sex with men; however, the trajectory of the outbreak remains uncertain, with spread now being reported in women and children. The mortality has been low (<1%), yet the morbidity is high. Vaccines and oral antiviral agents that have been developed to protect against smallpox are available for use against monkeypox. However, the supply has been unable to match the demand during the outbreak. Passive antibody-based therapies, such as hyperimmune globulin (HIG), monoclonal antibodies, and convalescent plasma (CP), have been used against a diverse array of infectious diseases, culminating in their extensive use during the COVID-19 pandemic. Passive antibody-based therapies could play a role in the treatment of monkeypox, either as a temporizing role amid a shortfall in vaccines and antivirals or a complementary role to direct-acting antivirals. Drawing on the collective experience to date, there are regulatory, administrative, and logistical challenges to the implementation of antibody-based therapies. Their efficacy is contingent upon early administration and the presence of high-titer antibodies against the targeted pathogen. Research is needed to address questions pertaining to how to qualify HIG and CP and to determine their relative efficacy against MPXV, compared to antecedent therapies and preventative strategies. IMPORTANCE Monkeypox is an infection caused by the monkeypox virus (MPXV). The clinical findings in monkeypox include fever and rash. Historically, most cases of human monkeypox were reported in Africa. This changed in 2022, with a massive escalation in the number of cases across multiple countries, mainly affecting men who have sex with men. Although vaccines and oral antiviral medications are available for the treatment of monkeypox, their supply has been overwhelmed by the unprecedented number of cases. Antibody-based therapies (ABTs) have long been used to treat infectious diseases. They are produced in a laboratory or from plasma that has been collected from individuals who have recovered from an infection or have been vaccinated against that infection (in this case, monkeypox). ABTs could play a role in the treatment of monkeypox, either while awaiting oral medications or as a complementary treatment for patients that are at risk of severe disease.

Reduced Risk for Mpox After Receipt of 1 or 2 Doses of JYNNEOS Vaccine Compared with Risk Among Unvaccinated Persons - 43 U.S. Jurisdictions, July 31-October 1, 2022

As of October 28, 2022, a total of 28,244* monkeypox (mpox) cases have been reported in the United States during an outbreak that has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (1). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series (with doses administered 4 weeks apart), was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and mpox disease (2); an FDA Emergency Use Authorization issued on August 9, 2022, authorized intradermal administration of 0.1 mL per dose, increasing the number of persons who could be vaccinated with the available vaccine supply^† (3). A previous comparison of mpox incidence during July 31-September 3, 2022, among unvaccinated, but vaccine-eligible men aged 18-49 years and those who had received ≥1 JYNNEOS vaccine dose in 32 U.S. jurisdictions, found that incidence among unvaccinated persons was 14 times that among vaccinated persons (95% CI = 5.0-41.0) (4). During September 4-October 1, 2022, a total of 205,504 persons received JYNNEOS vaccine dose 2 in the United States.^§ To further examine mpox incidence among persons who were unvaccinated and those who had received either 1 or 2 JYNNEOS doses, investigators analyzed data on 9,544 reported mpox cases among men^¶ aged 18-49 years during July 31-October 1, 2022, from 43 U.S. jurisdictions,** by vaccination status. During this study period, mpox incidence (cases per 100,000 population at risk) among unvaccinated persons was 7.4 (95% CI = 6.0-9.1) times that among persons who received only 1 dose of JYNNEOS vaccine ≥14 days earlier and 9.6 (95% CI = 6.9-13.2) times that among persons who received dose 2 ≥14 days earlier. The observed distribution of subcutaneous and intradermal routes of administration of dose 1 among vaccinated persons with mpox was not different from the expected distribution. This report provides additional data suggesting JYNNEOS vaccine provides protection against mpox, irrespective of whether the vaccine is administered intradermally or subcutaneously. The degree and durability of such protection remains unclear. Persons eligible for mpox vaccination should receive the complete 2-dose series to optimize strength of protection^†† (5).

Severe mpox (formerly monkeypox) disease in five patients after recent vaccination with MVA-BN vaccine, Belgium, July to October 2022

Vaccination is important in containing the 2022 mpox (formerly monkeypox) epidemic. We describe five Belgian patients with localised severe symptoms of proctitis and penile oedema, occurring between 4 and 35 days after post-exposure preventive vaccination or after one- or two-dose off-label pre-exposure preventive vaccination with MVA-BN vaccine. Genome sequencing did not reveal evidence for immune escape variants. Healthcare workers and those at risk should be aware of possible infections occurring shortly after vaccination and the need for other preventive measures.

Prevention of monkeypox with vaccines: a rapid review

The largest outbreak of monkeypox in history began in May, 2022, and has rapidly spread across the globe ever since. The purpose of this Review is to briefly describe human immune responses to orthopoxviruses; provide an overview of the vaccines available to combat this outbreak; and discuss the various clinical data and animal studies evaluating protective immunity to monkeypox elicited by vaccinia virus-based smallpox vaccines, address ongoing concerns regarding the outbreak, and provide suggestions for the appropriate use of vaccines as an outbreak control measure. Data showing clinical effectiveness (~85%) of smallpox vaccines against monkeypox come from surveillance studies conducted in central Africa in the 1980s and later during outbreaks in the same area. These data are supported by a large number of animal studies (primarily in non-human primates) with live virus challenge by various inoculation routes. These studies uniformly showed a high degree of protection and immunity against monkeypox virus following vaccination with various smallpox vaccines. Smallpox vaccines represent an effective countermeasure that can be used to control monkeypox outbreaks. However, smallpox vaccines do cause side-effects and the replication-competent, second-generation vaccines have contraindications. Third-generation vaccines, although safer for use in immunocompromised populations, require two doses, which is an impediment to rapid outbreak response. Lessons learned from the COVID-19 pandemic should be used to inform our collective response to this monkeypox outbreak and to future outbreaks.

Summary of the National Advisory Committee on Immunization (NACI) Rapid Response: Updated interim guidance on Imvamune in the context of ongoing monkeypox outbreaks

Background

During the period of monkeypox community transmission and restricted vaccine supply in the summer of 2022, Canadian provinces and territories and a number of vaccine stakeholders indicated the need for consistent national guidance on pre-exposure vaccination (including the identification of priority populations for pre-exposure vaccination programs) and guidance on the potential use of dose-sparing strategies.

Methods

The National Advisory Committee on Immunization (NACI) High Consequence Infectious Disease Working Group reviewed data on the status of the monkeypox outbreak along with additional published and non-published evidence regarding the safety, immunogenicity and protection offered by Imvamune®. NACI approved updated recommendations on September 16, 2022, and on September 23, 2022 it released updated interim guidance on the use of Imvamune in the context of the ongoing monkeypox outbreak.

Results

During periods of adequate vaccine supply, NACI recommended that Imvamune pre-exposure vaccination should be offered as a two-dose primary series, with at least 28 days between the two sub-cutaneous doses. When supply is limited, guidance was provided for the use of dose sparing strategies, including extended dosing intervals and fractional intradermal dosing to maximize vaccine coverage for those at highest risk of exposure to the monkeypox virus.

Conclusion

The updated NACI recommendations provide additional guidance on the use of Imvamune for the management of the 2022 monkeypox outbreak in Canada and may be considered to maximize vaccine coverage in outbreak settings when supply is limited.

Monkeypox: epidemiology, pathogenesis, treatment and prevention

Monkeypox is a zoonotic disease that was once endemic in west and central Africa caused by monkeypox virus. However, cases recently have been confirmed in many nonendemic countries outside of Africa. WHO declared the ongoing monkeypox outbreak to be a public health emergency of international concern on July 23, 2022, in the context of the COVID-19 pandemic. The rapidly increasing number of confirmed cases could pose a threat to the international community. Here, we review the epidemiology of monkeypox, monkeypox virus reservoirs, novel transmission patterns, mutations and mechanisms of viral infection, clinical characteristics, laboratory diagnosis and treatment measures. In addition, strategies for the prevention, such as vaccination of smallpox vaccine, is also included. Current epidemiological data indicate that high frequency of human-to-human transmission could lead to further outbreaks, especially among men who have sex with men. The development of antiviral drugs and vaccines against monkeypox virus is urgently needed, despite some therapeutic effects of currently used drugs in the clinic. We provide useful information to improve the understanding of monkeypox virus and give guidance for the government and relative agency to prevent and control the further spread of monkeypox virus.

Developing a Feline Immunodeficiency Virus Subtype B Vaccine Prototype Using a Recombinant MVA Vector

The feline immunodeficiency virus (FIV) is a retrovirus with global impact and distribution, affecting both domestic and wild cats. This virus can cause severe and progressive immunosuppression culminating in the death of felids. Since the discovery of FIV, only one vaccine has been commercially available. This vaccine has proven efficiency against FIV subtypes A and D, whereas subtype B (FIV-B), found in multiple continents, is not currently preventable by vaccination. We, therefore, developed and evaluated a vaccine prototype against FIV-B using the recombinant viral vector modified vaccinia virus Ankara (MVA) expressing the variable region V1-V3 of the FIV-B envelope protein. We conducted preclinical tests in immunized mice (C57BL/6) using a prime-boost protocol with a 21 day interval and evaluated cellular and humoral responses as well the vaccine viability after lyophilization and storage. The animals immunized with the recombinant MVA/FIV virus developed specific splenocyte proliferation when stimulated with designed peptides. We also detected cellular and humoral immunity activation with IFN-y and antibody production. The data obtained in this study support further development of this immunogen and testing in cats.

Dose optimisation and scarce resource allocation: two sides of the same coin

OBJECTIVE

A deep understanding of the relationship between a scarce drug's dose and clinical response is necessary to appropriately distribute a supply-constrained drug along these lines.

SUMMARY OF KEY DATA

The vast majority of drug development and repurposing during the COVID-19 pandemic - an event that has made clear the ever-present scarcity in healthcare systems -has been ignorant of scarcity and dose optimisation's ability to help address it.

CONCLUSIONS

Future pandemic clinical trials systems should obtain dose optimisation data, as these appear necessary to enable appropriate scarce resource allocation according to societal values.

Does an Intradermal Vaccination for Monkeypox Make Sense?

Mankind has recently had to deal a series of virus-mediated pandemics, resulting in extensive morbidity and mortality rates that have severely strained healthcare systems. While dealing with viral infections as a healthcare concern is not new, our exceptionally mobile society has added to the critical challenge of limiting pathogen spread of a highly transmissible virus prior to the generation, testing, and distribution of safe and effective vaccines. The tremendous global effort put forth to address the recent pandemic induced by SARS-CoV-2 infection has highlighted many of the strengths and weaknesses of how vaccines are identified, tested, and used to provide protection. These uncertainties are exacerbated by the lack of clear and consistent messaging that can occur when the processes of research, development, and clinical testing that normally requires years of study and consideration are compressed into a few months. In this commentary, I will provide some background on the intramuscular (IM), subcutaneous (SC), and intradermal (ID) administration routes used for injectable vaccines and some information on potential immunological outcomes. With this background, I will address the recent FDA decision to allow an approved vaccine against monkeypox virus to be administered by ID, as well as its initial approval route via SC, injection as a dose-sparing strategy to maximize immunization numbers using current stockpiles.

The resurgence of a neglected orthopoxvirus: Immunologic and clinical aspects of monkeypox virus infections over the past six decades

Monkeypox is a zoonotic Orthopoxvirus which has predominantly affected humans living in western and central Africa since the 1970s. Type I and II interferon signaling, NK cell function, and serologic immunity are critical for host immunity against monkeypox. Monkeypox can evade host viral recognition and block interferon signaling, leading to overall case fatality rates of up to 11%. The incidence of monkeypox has increased since cessation of smallpox vaccination. In 2022, a global outbreak emerged, predominantly affecting males, with exclusive human-to-human transmission and more phenotypic variability than earlier outbreaks. Available vaccines are safe and effective tools for prevention of severe disease, but supply is limited. Now considered a public health emergency, more studies are needed to better characterize at-risk populations and to develop new anti-viral therapies.

Preventing the Next Pandemic: Is Live Vaccine Efficacious against Monkeypox, or Is There a Need for Killed Virus and mRNA Vaccines?

(1) Background: The monkeypox virus (MPV) is a double-stranded DNA virus belonging to the Poxviridae family, Chordopoxvirinae subfamily, and Orthopoxvirus genus. It was called monkeypox because it was first discovered in monkeys, in a Danish laboratory, in 1958. However, the actual reservoir for MPV is still unknown. (2) Methods and Results: We have reviewed the existing literature on the options for Monkeypox virus. There are three available vaccines for orthopoxviruses-ACAM2000, JYNNEOS, and LC16-with the first being a replicating vaccine and the latter being non- or minimally replicating. (3) Conclusions: Smallpox vaccinations previously provided coincidental immunity to MPV. ACAM2000 (a live-attenuated replicating vaccine) and JYNNEOS (a live-attenuated, nonreplicating vaccine) are two US FDA-approved vaccines that can prevent monkeypox. However, ACAM2000 may cause serious side effects, including cardiac problems, whereas JYNNEOS is associated with fewer complications. The recent outbreaks across the globe have once again highlighted the need for constant monitoring and the development of novel prophylactic and therapeutic modalities. Based on available data, there is still a need to develop an effective and safe new generation of vaccines specific for monkeypox that are killed or developed into a mRNA vaccine before monkeypox is declared a pandemic.

OC, Mohana Borges RDS, Tanuri A, Souza TML, Rossi-Bergmann B, Vale AM, Silva JL, de Oliveira AC, Filardy AD, Gomes AMO, de Matos Guedes HL. Immunogenicity of SARS-CoV-2 Trimeric Spike Protein Associated to Poly(I:C) Plus Alum

The SARS-CoV-2 pandemic has had a social and economic impact worldwide, and vaccination is an efficient strategy for diminishing those damages. New adjuvant formulations are required for the high vaccine demands, especially adjuvant formulations that induce a Th1 phenotype. Herein we assess a vaccination strategy using a combination of Alum and polyinosinic:polycytidylic acid [Poly(I:C)] adjuvants plus the SARS-CoV-2 spike protein in a prefusion trimeric conformation by an intradermal (ID) route. We found high levels of IgG anti-spike antibodies in the serum by enzyme linked immunosorbent assay (ELISA) and high neutralizing titers against SARS-CoV-2 in vitro by neutralization assay, after two or three immunizations. By evaluating the production of IgG subtypes, as expected, we found that formulations containing Poly(I:C) induced IgG2a whereas Alum did not. The combination of these two adjuvants induced high levels of both IgG1 and IgG2a. In addition, cellular immune responses of CD4+ and CD8+ T cells producing interferon-gamma were equivalent, demonstrating that the Alum + Poly(I:C) combination supported a Th1 profile. Based on the high neutralizing titers, we evaluated B cells in the germinal centers, which are specific for receptor-binding domain (RBD) and spike, and observed that more positive B cells were induced upon the Alum + Poly(I:C) combination. Moreover, these B cells produced antibodies against both RBD and non-RBD sites. We also studied the impact of this vaccination preparation [spike protein with Alum + Poly(I:C)] in the lungs of mice challenged with inactivated SARS-CoV-2 virus. We found a production of IgG, but not IgA, and a reduction in neutrophil recruitment in the bronchoalveolar lavage fluid (BALF) of mice, suggesting that our immunization scheme reduced lung inflammation. Altogether, our data suggest that Alum and Poly(I:C) together is a possible adjuvant combination for vaccines against SARS-CoV-2 by the intradermal route.

Effectiveness of COVID-19 vaccines and their challenges (Review)

At the end of 2019, a new disease recognized such as severe acute respiratory syndrome (SARS), was reported in Wuhan, China. This disease was caused by an unknown SARS coronavirus 2 (SARS-CoV-2); a virus is characterized by high infectivity among humans. In some cases, this disease can be asymptomatic, while in other cases can induce flu-like symptoms or acute respiratory distress syndrome, pneumonia and death. For this reason, the World Health Organization and Public Health Emergency of International Concern declared a pandemic status in January 2020. Currently, numerous countries have been involved in the development of effective vaccines to protect humans against SARS-CoV-2 infection. The present review will discuss the four vaccines, AZD1222 (AstraZeneca or Vaxzevria), Janssen (Ad26.COV2.S), Moderna/mRNA-1273 and BioNTech/Fosun/Pfizer BNT162b1, that are currently in use worldwide to understand their efficacy, but also evaluate the difficulties and challenges of vaccine development. Although several questions should be addressed regarding these vaccines, the current review will examine the viral elements used in the coronavirus-19 vaccine that can play a crucial role in inducing a strong immune response, as well as the different adverse effects that they can cause to individuals.

Human Antibody Responses Following Vaccinia Immunization Using Protein Microarrays and Correlation With Cell-Mediated Immunity and Antibody-Dependent Cellular Cytotoxicity Responses

BACKGROUND

There are limited data regarding immunological correlates of protection for the modified vaccinia Ankara (MVA) smallpox vaccine.

METHODS

A total of 523 vaccinia-naive subjects were randomized to receive 2 vaccine doses, as lyophilized MVA given subcutaneously, liquid MVA given subcutaneously (liquid-SC group), or liquid MVA given intradermally (liquid-ID group) 28 days apart. For a subset of subjects, antibody-dependent cellular cytotoxicity (ADCC), interferon-γ release enzyme-linked immunospot (ELISPOT), and protein microarray antibody-binding assays were conducted. Protein microarray responses were assessed for correlations with plaque reduction neutralization titer (PRNT), enzyme-linked immunosorbent assay, ADCC, and ELISPOT results.

RESULTS

MVA elicited significant microarray antibody responses to 15 of 224 antigens, mostly virion membrane proteins, at day 28 or 42, particularly WR113/D8L and WR101H3L. In the liquid-SC group, responses to 9 antigens, including WR113/D8L and WR101/H3L, correlated with PRNT results. Three were correlated in the liquid-ID group. No significant correlations were observed with ELISPOT responses. In the liquid-ID group, WR052/F13L, a membrane glycoprotein, correlated with ADCC responses.

CONCLUSIONS

MVA elicited antibodies to 15 vaccinia strain antigens representing virion membrane. Antibody responses to 2 proteins strongly increased and significantly correlated with increases in PRNT. Responses to these proteins are potential correlates of protection and may serve as immunogens for future vaccine development.

CLINICAL TRIALS REGISTRATION

NCT00914732.

The Brighton Collaboration standardized template for collection of key information for risk/benefit assessment of a Modified Vaccinia Ankara (MVA) vaccine platform

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety and characteristics of live, recombinant viral vector vaccines. The Modified Vaccinia Ankara (MVA) vector system is being explored as a platform for development of multiple vaccines. This paper reviews the molecular and biological features specifically of the MVA-BN vector system, followed by a template with details on the safety and characteristics of an MVA-BN based vaccine against Zaire ebolavirus and other filovirus strains. The MVA-BN-Filo vaccine is based on a live, highly attenuated poxviral vector incapable of replicating in human cells and encodes glycoproteins of Ebola virus Zaire, Sudan virus and Marburg virus and the nucleoprotein of the Thai Forest virus. This vaccine has been approved in the European Union in July 2020 as part of a heterologous Ebola vaccination regimen. The MVA-BN vector is attenuated following over 500 serial passages in eggs, showing restricted host tropism and incompetence to replicate in human cells. MVA has six major deletions and other mutations of genes outside these deletions, which all contribute to the replication deficiency in human and other mammalian cells. Attenuation of MVA-BN was demonstrated by safe administration in immunocompromised mice and non-human primates. In multiple clinical trials with the MVA-BN backbone, more than 7800 participants have been vaccinated, demonstrating a safety profile consistent with other licensed, modern vaccines. MVA-BN has been approved as smallpox vaccine in Europe and Canada in 2013, and as smallpox and monkeypox vaccine in the US in 2019. No signal for inflammatory cardiac disorders was identified throughout the MVA-BN development program. This is in sharp contrast to the older, replicating vaccinia smallpox vaccines, which have a known risk for myocarditis and/or pericarditis in up to 1 in 200 vaccinees. MVA-BN-Filo as part of a heterologous Ebola vaccination regimen (Ad26.ZEBOV/MVA-BN-Filo) has undergone clinical testing including Phase III in West Africa and is currently in use in large scale vaccination studies in Central African countries. This paper provides a comprehensive picture of the MVA-BN vector, which has reached regulatory approvals, both as MVA-BN backbone for smallpox/monkeypox, as well as for the MVA-BN-Filo construct as part of an Ebola vaccination regimen, and therefore aims to provide solutions to prevent disease from high-consequence human pathogens.

The Ebola virus glycoprotein and its immune responses across multiple vaccine platforms

Introduction: For over 40 years, ebolaviruses have been responsible for sporadic outbreaks of severe and often fatal hemorrhagic fever in humans and nonhuman primates across western and central Africa. In December 2013, an unprecedented Ebola virus (EBOV) epidemic began in West Africa and resulted in the largest outbreak to date. The past and current epidemics in West Africa and the Democratic Republic of the Congo has focused attention on the potential vaccine platforms developed over the past 20 years.Areas covered: This review summarizes the extraordinary progress using a variety of vaccination platforms including DNA, subunit, and several viral vector approaches, replicating and non-replicating, incorporating the primary antigen of EBOV, the glycoprotein. These vaccine constructs have shown varying degrees of protective efficacy in the 'gold-standard' nonhuman primate model for EBOV infections and were immunogenic in human clinical trials.Expert commentary: A number of these vaccine platforms have moved into phase III clinical trials over the past years and with the recent approval of the first EBOV vaccine in the European Union and the USA there is a strong potential to prevent future outbreaks/epidemics of EBOV infections on the scale of the West African epidemic.

A randomized phase II trial to compare safety and immunogenicity of the MVA-BN smallpox vaccine at various doses in adults with a history of AIDS

Traditional replicating smallpox vaccines are associated with serious safety concerns in the general population and are contraindicated in immunocompromised individuals. However, this very population remains at greatest risk for severe complications following viral infections, making vaccine prevention particularly relevant. MVA-BN was developed as a non-replicating smallpox vaccine that is potentially safer for people who are immunocompromised. In this phase II trial, 3 MVA-BN dosing regimens were evaluated for safety, tolerability, and immunogenicity in persons with HIV (PWH) who had a history of AIDS. Following randomization, 87 participants who were predominately male and African American received either 2 standard doses on weeks 0 and 4 in the standard dose (SD) group (N = 27), 2 double-standard doses on the same schedule in the double dose (DD) group (N = 29), or 3 standard doses on weeks 0, 4 and 12 in the booster dose (BD) group (N = 31). No safety concerns were identified, and injection site pain was the most commonly reported solicited adverse event (AE) in all groups (66.7%), with no meaningful differences between groups. The incidence of severe (Grade 3) AEs was low across groups and no serious AEs or AEs of special interest considered related to study vaccine were reported. Doubling the standard MVA-BN dose had no significant effect on induction of neutralizing antibodies, with 100% seroconversion and comparable GMTs at week 6 in the SD and DD groups (78.9 and 100.3, respectively). A booster dose significantly increased peak neutralizing titers in the BD group (GMT: 281.1), which remained elevated at 12 months (GMT: 45.3) compared to the SD (GMT: 6.2) and DD (GMT: 10.6) groups. However, based on the immune response previously reported for healthy participants, a third dose (booster) does not appear necessary, even for immunocompromised participants. Clinical Trial Registry Number: NCT02038881.

Safety and immunogenicity of novel modified vaccinia Ankara-vectored RSV vaccine: A randomized phase I clinical trial

Respiratory disease caused by RSV infection is recognized as a severe public health issue in infants, young children and elderly with no specific treatment option. Vaccination may be the most effective strategy to combat this highly infectious virus although no vaccine has been approved. The novel vaccine candidate MVA-BN-RSV encodes RSV surface proteins F and G (subtypes A, B) as well as internal proteins N and M2 in the MVA-BN viral vector backbone to provide broad protection against RSV. This was a first in human study to investigate safety, reactogenicity and immunogenicity of MVA-BN-RSV. Sixty-three participants were allocated to 3 groups: adult (18-49 years) low (1 × 10⁷ TCID₅₀) or high (1 × 10⁸ TCID₅₀) dose and older adult (50-65 years) high dose. Participants in each group were randomized in a 6:1 ratio to receive 2 doses of MVA-BN-RSV or placebo 4 weeks apart and were monitored for 30 weeks. All participants completed the study, receiving both doses. No serious AEs or AEs of special interest were reported. The most common AEs were injection site pain (56% in the combined high dose groups, 17% in the low dose group). MVA-BN-RSV induced robust T cell responses covering all 5 inserts with fold increases ranging from 1.8 to 3.8. Higher and broader responses were observed in the high dose groups (83% responders to at least 3 peptide pools in the combined high dose groups compared to 63% in the low dose group). Moderate but consistent humoral responses were observed against A and B RSV subtypes (up to approximately 2-fold increases in the high dose groups). No differences were observed between the adult and the older adult groups in safety, reactogenicity or immunogenicity. The study demonstrated that the well tolerated MVA-BN-RSV vaccine candidate induces broad cellular and humoral immune responses, warranting further development.

Role of Multivalency and Antigenic Threshold in Generating Protective Antibody Responses

Vaccines play a vital role in protecting our communities against infectious disease. Unfortunately, some vaccines provide only partial protection or in some cases vaccine-mediated immunity may wane rapidly, resulting in either increased susceptibility to that disease or a requirement for more booster vaccinations in order to maintain immunity above a protective level. The durability of antibody responses after infection or vaccination appears to be intrinsically determined by the structural biology of the antigen, with multivalent protein antigens often providing more long-lived immunity than monovalent antigens. This forms the basis for the Imprinted Lifespan model describing the differential survival of long-lived plasma cell populations. There are, however, exceptions to this rule with examples of highly attenuated live virus vaccines that are rapidly cleared and elicit only short-lived immunity despite the expression of multivalent surface epitopes. These exceptions have led to the concept that multivalency alone may not reliably determine the duration of protective humoral immune responses unless a minimum number of long-lived plasma cells are generated by reaching an appropriate antigenic threshold of B cell stimulation. Examples of long-term and in some cases, potentially lifelong antibody responses following immunization against human papilloma virus (HPV), Japanese encephalitis virus (JEV), Hepatitis B virus (HBV), and Hepatitis A virus (HAV) provide several lessons in understanding durable serological memory in human subjects. Moreover, studies involving influenza vaccination provide the unique opportunity to compare the durability of hemagglutinin (HA)-specific antibody titers mounted in response to antigenically repetitive whole virus (i.e., multivalent HA), or detergent-disrupted “split” virus, in comparison to the long-term immune responses induced by natural influenza infection. Here, we discuss the underlying mechanisms that may be associated with the induction of protective immunity by long-lived plasma cells and their importance in future vaccine design.

Vaccinating against monkeypox in the Democratic Republic of the Congo

Healthcare-associated transmission of monkeypox has been observed on multiple occasions in areas where the disease is endemic. Data collected by the US Centers for Disease Control and Prevention (CDC) from an ongoing CDC-supported program of enhanced surveillance in the Tshuapa Province of the Democratic Republic of the Congo, where the annual incidence of human monkeypox is estimated to be 3.5-5/10,000, suggests that there is approximately one healthcare worker infection for every 100 confirmed monkeypox cases. Herein, we describe a study that commenced in February 2017, the intent of which is to evaluate the effectiveness, immunogenicity, and safety of a third-generation smallpox vaccine, IMVAMUNE®, in healthcare personnel at risk of monkeypox virus (MPXV) infection. We describe procedures for documenting exposures to monkeypox virus infection in study participants, and outline lessons learned that may be of relevance for studies of other investigational medical countermeasures in hard to reach, under-resourced populations.

Poxvirus-based vector systems and the potential for multi-valent and multi-pathogen vaccines

INTRODUCTION

With the increasing number of vaccines and vaccine-preventable diseases, the pressure to generate multi-valent and multi-pathogen vaccines grows. Combining individual established vaccines to generate single-shot formulations represents an established path, with significant ensuing public health and cost benefits. Poxvirus-based vector systems have the capacity for large recombinant payloads and have been widely used as platforms for the development of recombinant vaccines encoding multiple antigens, with considerable clinical trials activity and a number of registered and licensed products.

AREAS COVERED

Herein we discuss design strategies, production processes, safety issues, regulatory hurdles and clinical trial activities, as well as pertinent new technologies such as systems vaccinology and needle-free delivery. Literature searches used PubMed, Google Scholar and clinical trials registries, with a focus on the recombinant vaccinia-based systems, Modified Vaccinia Ankara and the recently developed Sementis Copenhagen Vector.

EXPERT COMMENTARY

Vaccinia-based platforms show considerable promise for the development of multi-valent and multi-pathogen vaccines, especially with recent developments in vector technologies and manufacturing processes. New methodologies for defining immune correlates and human challenge models may also facilitate bringing such vaccines to market.

New Vaccine Technologies to Combat Outbreak Situations

Ever since the development of the first vaccine more than 200 years ago, vaccinations have greatly decreased the burden of infectious diseases worldwide, famously leading to the eradication of small pox and allowing the restriction of diseases such as polio, tetanus, diphtheria, and measles. A multitude of research efforts focuses on the improvement of established and the discovery of new vaccines such as the HPV (human papilloma virus) vaccine in 2006. However, radical changes in the density, age distribution and traveling habits of the population worldwide as well as the changing climate favor the emergence of old and new pathogens that bear the risk of becoming pandemic threats. In recent years, the rapid spread of severe infections such as HIV, SARS, Ebola, and Zika have highlighted the dire need for global preparedness for pandemics, which necessitates the extremely rapid development and comprehensive distribution of vaccines against potentially previously unknown pathogens. What is more, the emergence of antibiotic resistant bacteria calls for new approaches to prevent infections. Given these changes, established methods for the identification of new vaccine candidates are no longer sufficient to ensure global protection. Hence, new vaccine technologies able to achieve rapid development as well as large scale production are of pivotal importance. This review will discuss viral vector and nucleic acid-based vaccines (DNA and mRNA vaccines) as new approaches that might be able to tackle these challenges to global health.

Immunogenicity and safety of three consecutive production lots of the non replicating smallpox vaccine MVA: A randomised, double blind, placebo controlled phase III trial

Background

Modified Vaccinia Ankara (MVA) is a live, viral vaccine under advanced development as a non-replicating smallpox vaccine. A randomised, double-blind, placebo-controlled phase III clinical trial was conducted to demonstrate the humoral immunogenic equivalence of three consecutively manufactured MVA production lots, and to confirm the safety and tolerability of MVA focusing on cardiac readouts.

Methods

The trial was conducted at 34 sites in the US. Vaccinia-naïve adults aged 18-40 years were randomly allocated to one of four groups using a 1:1:1:1 randomization scheme. Subjects received either two MVA injections from three consecutive lots (Groups 1-3), or two placebo injections (Group 4), four weeks apart. Everyone except personnel involved in vaccine handling and administration was blinded to treatment. Safety assessment focused on cardiac monitoring throughout the trial. Vaccinia-specific antibody titers were measured using a Plaque Reduction Neutralization Test (PRNT) and an Enzyme-Linked Immunosorbent Assay (ELISA). The primary immunogenicity endpoint was Geometric Mean Titers (GMTs) after two MVA vaccinations measured by PRNT at trial visit 4. This trial is registered with ClinicalTrials.gov, number NCT01144637.

Results

Between March 2013 and May 2014, 4005 subjects were enrolled and received at least one injection of MVA (n = 3003) or placebo (n = 1002). The three MVA lots induced equivalent antibody titers two weeks after the second vaccination, with seroconversion rates of 99·8% (PRNT) and 99·7% (ELISA). Overall, 180 (6·0%) subjects receiving MVA and 29 (2·9%) subjects in the placebo group reported at least one unsolicited Adverse Event (AE) that was considered trial-related. Vaccination was well tolerated without significant safety concerns, particularly regarding cardiac assessment.

Conclusions

The neutralizing and total antibody titers induced by each of the three lots were equivalent. No significant safety concerns emerged in this healthy trial population, especially regarding cardiac safety, thus confirming the excellent safety and tolerability profile of MVA.

Trial registration

ClinicalTrials.gov NCT01144637

Topically applied virus-like particles containing HIV-1 Pr55gag protein reach skin antigen-presenting cells after mild skin barrier disruption

Loading of antigen on particles as well as the choice of skin as target organ for vaccination were independently described as effective dose-sparing strategies for vaccination. Combining these two strategies, sufficient antigen recognition may be achievable via the transcutaneous route even with minimal-invasive tools. Here, we investigated the skin penetration and cellular uptake of topically administered virus-like particles (VLPs), composed of the HIV-1 precursor protein Pr55^gag, as well as the migratory activity of skin antigen-presenting cells (APCs). We compared VLP administration on ex vivo human skin pre-treated with cyanoacrylate tape stripping (CSSS, minimal-invasive) to administration by skin pricking and intradermal injection (invasive). CSSS as well as pricking treatments resulted in penetration of VLPs in the viable skin layers. Electron microscopy confirmed that at least part of VLPs remained intact during the penetration process. Flow cytometry of epidermal, dermal, and HLA-DR⁺ APCs harvested from culture media of skin explants cultivated at air-liquid interface revealed that a number of cells had taken-up VLPs. Similar results were found between invasive and minimal-invasive VLP application methods. CSSS pre-treatment was associated with significantly increased levels of IL-1α levels in cell culture media as compared to untreated and pricked skin. Our findings provide first evidence for effective cellular uptake of VLPs after dermal application and indicate that even mild physical barrier disruption, as induced by CSSS, provides stimulatory signals that enable the activation of APCs and uptake of large antigenic material.

Safety and immunogenicity of a modified vaccinia Ankara vaccine using three immunization schedules and two modes of delivery: A randomized clinical non-inferiority trial

INTRODUCTION

To guide the use of modified vaccinia Ankara (MVA) vaccine in response to a release of smallpox virus, the immunogenicity and safety of shorter vaccination intervals, and administration by jet injector (JI), were compared to the standard schedule of administration on Days 1 and 29 by syringe and needle (S&N).

METHODS

Healthy adults 18-40years of age were randomly assigned to receive MVA vaccine subcutaneously by S&N on Days 1 and 29 (standard), Days 1 and 15, or Days 1 and 22, or to receive the vaccine subcutaneously by JI on Days 1 and 29. Blood was collected at four time points after the second vaccination for plaque reduction neutralization test (PRNT) (primary endpoint) and ELISA (secondary endpoint) antibody assays. For each subject, the peak PRNT (or ELISA) titer was defined by the highest PRNT (or ELISA) titer among all available measurements post second vaccination. Non-inferiority of a non-standard arm compared to the standard arm was met if the upper limit of the 98.33% confidence interval of the difference in the mean log₂ peak titers between the standard and non-standard arm was less than 1.

RESULTS

Non-inferiority of the PRNT antibody response was not established for any of the three non-standard study arms. Non-inferiority of the ELISA antibody response was established for the Day 1 and 22 compressed schedule and for administration by JI. Solicited local reactions, such as redness and swelling, tended to be more commonly reported with JI administration. Four post-vaccination hypersensitivity reactions were observed.

CONCLUSIONS

Evaluations of the primary endpoint of PRNT antibody responses do not support alternative strategies of administering MVA vaccine by S&N on compressed schedules or administration by JI on the standard schedule.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01827371.

Questions regarding the safety and duration of immunity following live yellow fever vaccination

INTRODUCTION

The World Health Organization (WHO) and other health agencies have concluded that yellow fever booster vaccination is unnecessary since a single dose of vaccine confers lifelong immunity. Areas covered: We reviewed the clinical studies cited by health authorities in their investigation of both the safety profile and duration of immunity for the YFV-17D vaccine and examined the position that booster vaccination is no longer needed. We found that antiviral immunity may be lost in 1-in-3 to 1-in-5 individuals within 5 to 10 years after a single vaccination and that children may be at greater risk for primary vaccine failure. The safety profile of YFV-17D was compared to other licensed vaccines including oral polio vaccine (OPV) and the rotavirus vaccine, RotaShield, which have subsequently been withdrawn from the US and world market, respectively. Expert commentary: Based on these results and recent epidemiological data on vaccine failures (particularly evident at >10 years after vaccination), we believe that current recommendations to no longer administer YFV-17D booster vaccination be carefully re-evaluated, and that further development of safer vaccine approaches should be considered.

Modified Vaccinia Virus Ankara: History, Value in Basic Research, and Current Perspectives for Vaccine Development

Safety tested Modified Vaccinia virus Ankara (MVA) is licensed as third-generation vaccine against smallpox and serves as a potent vector system for development of new candidate vaccines against infectious diseases and cancer. Historically, MVA was developed by serial tissue culture passage in primary chicken cells of vaccinia virus strain Ankara, and clinically used to avoid the undesirable side effects of conventional smallpox vaccination. Adapted to growth in avian cells MVA lost the ability to replicate in mammalian hosts and lacks many of the genes orthopoxviruses use to conquer their host (cell) environment. As a biologically well-characterized mutant virus, MVA facilitates fundamental research to elucidate the functions of poxvirus host-interaction factors. As extremely safe viral vectors MVA vaccines have been found immunogenic and protective in various preclinical infection models. Multiple recombinant MVA currently undergo clinical testing for vaccination against human immunodeficiency viruses, Mycobacterium tuberculosis or Plasmodium falciparum. The versatility of the MVA vector vaccine platform is readily demonstrated by the swift development of experimental vaccines for immunization against emerging infections such as the Middle East Respiratory Syndrome. Recent advances include promising results from the clinical testing of recombinant MVA-producing antigens of highly pathogenic avian influenza virus H5N1 or Ebola virus. This review summarizes our current knowledge about MVA as a unique strain of vaccinia virus, and discusses the prospects of exploiting this virus as research tool in poxvirus biology or as safe viral vector vaccine to challenge existing and future bottlenecks in vaccinology.

A Randomized, Double-Blind, Placebo-Controlled Phase II Trial Investigating the Safety and Immunogenicity of Modified Vaccinia Ankara Smallpox Vaccine (MVA-BN®) in 56-80-Year-Old Subjects

BACKGROUND

Modified Vaccinia Ankara MVA-BN® is a live, highly attenuated, viral vaccine under advanced development as a non-replicating smallpox vaccine. In this Phase II trial, the safety and immunogenicity of Modified Vaccinia Ankara MVA-BN® (MVA) was assessed in a 56-80 years old population.

METHODS

MVA with a virus titer of 1 x 108 TCID50/dose was administered via subcutaneous injection to 56-80 year old vaccinia-experienced subjects (N = 120). Subjects received either two injections of MVA (MM group) or one injection of Placebo and one injection of MVA (PM group) four weeks apart. Safety was evaluated by assessment of adverse events (AE), focused physical exams, electrocardiogram recordings and safety laboratories. Solicited AEs consisted of a set of pre-defined expected local reactions (erythema, swelling, pain, pruritus, and induration) and systemic symptoms (body temperature, headache, myalgia, nausea and fatigue) and were recorded on a memory aid for an 8-day period following each injection. The immunogenicity of the vaccine was evaluated in terms of humoral immune responses measured with a vaccinia-specific enzyme-linked immunosorbent assay (ELISA) and a plaque reduction neutralization test (PRNT) before and at different time points after vaccination.

RESULTS

Vaccinations were well tolerated by all subjects. No serious adverse event related to MVA and no case of myopericarditis was reported. The overall incidence of unsolicited AEs was similar in both groups. For both groups immunogenicity responses two weeks after the final vaccination (i.e. Visit 4) were as follows: Seroconversion (SC) rates (doubling of titers from baseline) in vaccine specific antibody titers measured by ELISA were 83.3% in Group MM and 82.8% in Group PM (difference 0.6% with 95% exact CI [-13.8%, 15.0%]), and 90.0% for Group MM and 77.6% for Group PM measured by PRNT (difference 12.4% with 95% CI of [-1.1%, 27.0%]). Geometric mean titers (GMT) measured by ELISA two weeks after the final vaccination for Group MM were 804.1 and 605.8 for Group PM (with ratio of GMTs of 1.33 with 95% CI of [0.96, 1.84]). Similarly, GMTs measured by PRNT were 210.3 for Group MM and 126.7 for Group PM (with ratio 1.66 and 95% CI [0.95, 2.90]).

CONCLUSIONS

One or two doses of MVA were safe and immunogenic in a 56-80 years old vaccinia-experienced population. No cases of myopericarditis were observed following vaccinations with MVA. The safety, reactogenicity and immunogenicity were similar to that seen in younger (18-55 year old) healthy populations as investigated in other MVA trials. The results suggest that a single dose of MVA in a 56-80 years old population was well tolerated and sufficient to rapidly boost the long-term B cell memory response induced by a prior vaccination with a traditional smallpox vaccine.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00857493.

Defending against smallpox: a focus on vaccines

Smallpox has shaped human history, from the earliest human civilizations well into the 20th century. With high mortality rates, rapid transmission, and serious long-term effects on survivors, smallpox was a much-feared disease. The eradication of smallpox represents an unprecedented medical victory for the lasting benefit of human health and prosperity. Concerns remain, however, about the development and use of the smallpox virus as a biological weapon, which necessitates the need for continued vaccine development. Smallpox vaccine development is thus a much-reviewed topic of high interest. This review focuses on the current state of smallpox vaccines and their context in biodefense efforts.

Percutaneous Vaccination as an Effective Method of Delivery of MVA and MVA-Vectored Vaccines

The robustness of immune responses to an antigen could be dictated by the route of vaccine inoculation. Traditional smallpox vaccines, essentially vaccinia virus strains, that were used in the eradication of smallpox were administered by percutaneous inoculation (skin scarification). The modified vaccinia virus Ankara is licensed as a smallpox vaccine in Europe and Canada and currently undergoing clinical development in the United States. MVA is also being investigated as a vector for the delivery of heterologous genes for prophylactic or therapeutic immunization. Since MVA is replication-deficient, MVA and MVA-vectored vaccines are often inoculated through the intramuscular, intradermal or subcutaneous routes. Vaccine inoculation via the intramuscular, intradermal or subcutaneous routes requires the use of injection needles, and an estimated 10 to 20% of the population of the United States has needle phobia. Following an observation in our laboratory that a replication-deficient recombinant vaccinia virus derived from the New York City Board of Health strain elicited protective immune responses in a mouse model upon inoculation by tail scarification, we investigated whether MVA and MVA recombinants can elicit protective responses following percutaneous administration in mouse models. Our data suggest that MVA administered by percutaneous inoculation, elicited vaccinia-specific antibody responses, and protected mice from lethal vaccinia virus challenge, at levels comparable to or better than subcutaneous or intramuscular inoculation. High titers of specific neutralizing antibodies were elicited in mice inoculated with a recombinant MVA expressing the herpes simplex type 2 glycoprotein D after scarification. Similarly, a recombinant MVA expressing the hemagglutinin of attenuated influenza virus rgA/Viet Nam/1203/2004 (H5N1) elicited protective immune responses when administered at low doses by scarification. Taken together, our data suggest that MVA and MVA-vectored vaccines inoculated by scarification can elicit protective immune responses that are comparable to subcutaneous vaccination, and may allow for antigen sparing when vaccine supply is limited.