The Route of Vaccine Administration Determines Whether Blood Neutrophils Undergo Long-Term Phenotypic Modifications

Innate immunity modulates adaptive immunity and defines the magnitude, quality, and longevity of antigen-specific T- and B- cell immune memory. Various vaccine and administration factors influence the immune response to vaccination, including the route of vaccine delivery. We studied the dynamics of innate cell responses in blood using a preclinical model of non-human primates immunized with a live attenuated vaccinia virus, a recombinant Modified vaccinia virus Ankara (MVA) expressing a gag-pol-nef fusion of HIV-1, and mass cytometry. We previously showed that it induces a strong, early, and transient innate response, but also late phenotypic modifications of blood myeloid cells after two months when injected subcutaneously. Here, we show that the early innate effector cell responses and plasma inflammatory cytokine profiles differ between subcutaneous and intradermal vaccine injection. Additionally, we show that the intradermal administration fails to induce more highly activated/mature neutrophils long after immunization, in contrast to subcutaneous administration. Different batches of antibodies, staining protocols and generations of mass cytometers were used to generate the two datasets. Mass cytometry data were analyzed in parallel using the same analytical pipeline based on three successive clustering steps, including SPADE, and categorical heatmaps were compared using the Manhattan distance to measure the similarity between cell cluster phenotypes. Overall, we show that the vaccine per se is not sufficient for the late phenotypic modifications of innate myeloid cells, which are evocative of innate immune training. Its route of administration is also crucial, likely by influencing the early innate response, and systemic inflammation, and vaccine biodistribution.

Viral vector vaccines protect cockatiels from inflammatory lesions after heterologous parrot bornavirus 2 challenge infection

Avian bornaviruses are causative agents of proventricular dilatation disease (PDD), a chronic neurologic and often fatal disorder of psittacines including endangered species. To date no causative therapy or immunoprophylaxis is available. Our previous work has shown that viral vector vaccines can delay the course of homologous bornavirus challenge infections but failed to protect against PDD when persistent infection was not prevented. The goal of this study was to refine our avian bornavirus vaccination and infection model to better represent natural bornavirus infections in order to achieve full protection against a heterologous challenge infection. We observed that parrot bornavirus 2 (PaBV-2) readily infected cockatiels (Nymphicus hollandicus) by combined intramuscular and subcutaneous injection with as little as 10^2.7foci-forming units (ffu) per bird, whereas a 500-fold higher dose of the same virus administered via peroral and oculonasal route did not result in persistent infection. These results indicated that experimental bornavirus challenge infections with this virus should be performed via the parenteral route. Prime-boost vaccination of cockatiels with Newcastle disease virus (NDV) and modified vaccinia virus Ankara (MVA) vectors expressing the nucleoprotein and phosphoprotein genes of PaBV-4 substantially blocked bornavirus replication following parenteral challenge infection with 10^3.5ffu of heterologous PaBV-2. Only two out of six vaccinated birds had very low viral levels detectable in a few organs. As a consequence, only one vaccinated bird developed mild PDD-associated microscopic lesions, while mock-vaccinated controls were not protected against PaBV-2 infection and inflammation. Our results demonstrate that NDV and MVA vector vaccines can protect against invasive heterologous bornavirus challenge infections and subsequent PDD. These vector vaccines represent a promising tool to combat avian bornaviruses in psittacine populations.

Market implementation of the MVA platform for pre-pandemic and pandemic influenza vaccines: A quantitative key opinion leader analysis

A quantitative method is presented to rank strengths, weaknesses, opportunities, and threats (SWOT) of modified vaccinia virus Ankara (MVA) as a platform for pre-pandemic and pandemic influenza vaccines. Analytic hierarchy process (AHP) was applied to achieve pairwise comparisons among SWOT factors in order to prioritize them. Key opinion leaders (KOLs) in the influenza vaccine field were interviewed to collect a unique dataset to evaluate the market potential of this platform.

The purpose of this study, to evaluate commercial potential of the MVA platform for the development of novel generation pandemic influenza vaccines, is accomplished by using a SWOT and AHP combined analytic method. Application of the SWOT–AHP model indicates that its strengths are considered more important by KOLs than its weaknesses, opportunities, and threats. Particularly, the inherent immunogenicity capability of MVA without the requirement of an adjuvant is the most important factor to increase commercial attractiveness of this platform. Concerns regarding vector vaccines and anti-vector immunity are considered its most important weakness, which might lower public health value of this platform. Furthermore, evaluation of the results of this study emphasizes equally important role that threats and opportunities of this platform play.

This study further highlights unmet needs in the influenza vaccine market, which could be addressed by the implementation of the MVA platform. Broad use of MVA in clinical trials shows great promise for this vector as vaccine platform for pre-pandemic and pandemic influenza and threats by other respiratory viruses. Moreover, from the results of the clinical trials seem that MVA is particularly attractive for development of vaccines against pathogens for which no, or only insufficiently effective vaccines, are available.

PedVacc 002: a phase I/II randomized clinical trial of MVA.HIVA vaccine administered to infants born to human immunodeficiency virus type 1-positive mothers in Nairobi

BACKGROUND

A safe, effective vaccine for breastfeeding infants born to HIV-1-positive mothers could complement antiretroviral therapy (ART) for prevention of mother-to-child transmission of HIV-1. To date, only a few HIV-1 vaccine candidates have been tested in infants.

TRIAL DESIGN

A phase I/II randomized controlled trial PedVacc 002 was conducted to determine the safety and immunogenicity of a single, low dose of MVA.HIVA vaccine delivered intramuscularly to healthy 20-week-old infants born to HIV-1-positive mothers in Nairobi, Kenya.

METHODS

Pregnant HIV-1-positive women in the 2nd/3rd trimester of gestation were enrolled, provided with ART and self-selected their infant-feeding modality. Infants received nevirapine and cotrimoxazole prophylaxis. At 20 weeks of age, eligible HIV-1-negative infants were randomized to vaccine versus no-treatment arms and followed to 48 weeks of age for assessments of vaccine safety, HIV-1-specific T-cell responses and antibodies to routine childhood vaccines.

RESULTS

Between February and November 2010, 182 mothers were screened, 104 were eligible and followed on ART during pregnancy/postpartum, of whom 73 had eligible infants at 20 weeks postpartum. Thirty-six infants were randomized to vaccine and 37 to no treatment. Eighty-four percent of infants breastfed, and retention at 48 weeks was 99%. Adverse events were rare and similar between the two arms. HIV-1-specific T-cell frequencies in interferon-γ ELISPOT assay were transiently higher in the MVA.HIVA arm (p=0.002), but not above the threshold for a positive assay. Protective antibody levels were adequate and similar between arms for all routine childhood vaccines except HBV, where 71% of MVA.HIVA subjects compared to 92% of control subjects were protected (p=0.05).

CONCLUSIONS

This trial tested for the first time an MVA-vectored candidate HIV-1 vaccine in HIV-1-exposed infants in Africa, demonstrating trial feasibility and vaccine safety, low immunogenicity, and compatibility with routine childhood vaccinations. These results are reassuring for use of the MVA vector in more potent prime-boost regimens.

Absence of systemic toxicity changes following intramuscular administration of novel pSG2.HIVconsv DNA, ChAdV63.HIVconsv and MVA.HIVconsv vaccines to BALB/c mice

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Three novel vaccines were tested in 2 GLP toxicity studies in BALB/c mice.

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Vaccines were vectored by DNA, simian adenovirus and modified vaccinia virus Ankara.

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All 3 vaccines expressed the same conserved regions of HIV-1.

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Intramuscular administration had no systemic toxicity.

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All changes were consistent with i.m. delivery and immune response induction.

Background

The systemic toxicity of three candidate HIV-1 vaccines plasmid pSG2.HIVconsv DNA (D), ChAdV63.HIVconsv (C) and MVA.HIVconsv (M) expressing chimeric immunogen derived from the most conserved regions of the HIV-1 proteome was evaluated in two repeat-dose studies in the male and female BALB/c mice.

Methods

In study UNO011, mice received three doses of 2 × 10⁷ plaque-forming units of MVA.HIVconsv vaccine (MMM). In study UNO012, mice received 3 doses of 50 μg of pSG2.HIVconsv DNA followed by a single dose of 5.95 × 10⁹ virus particles of ChAdV63.HIVconsv vaccine (DDDC). Similarly constituted control groups received the vehicle alone (phosphate buffered saline) at the same volume-dose. All vaccines were administered by intramuscular needle injection into the right hind limb at 14-day intervals and animals were sacrificed 7 days after the last dose. Assessment of local and systemic toxicity was made. Induction of HIV-1-specific responses was confirmed. Parameters assessed included clinical condition, body weight, food consumption, ophthalmoscopy, haematology, blood chemistry, organ weight and macroscopic and microscopic pathology.

Results

In both studies, treatment with the candidate vaccines elicited strong HIV-1-specific T-cell responses. The vaccine treatment was well-tolerated without any adverse systemic toxicological changes. The local toxicity findings observed in these studies were consistent with the predicted response to a vaccine/substance administration by intramuscular injection.

Conclusions

The three novel anti-HIV-1 vaccines were well tolerated when administered by intramuscular injection to BALB/c mice. These results supported an application for authorisation by the Medicines and Healthcare Products Regulatory Agency of the UK to test these vaccines for the first time in phase I clinical trials in healthy both uninfected subjects and HIV-1-infected patients stable on antiretroviral treatment.

Recombinant MVA vaccines: dispelling the myths

Diseases such as HIV/AIDS, tuberculosis, malaria and cancer are prime targets for prophylactic or therapeutic vaccination, but have proven partially or wholly resistant to traditional approaches to vaccine design. New vaccines based on recombinant viral vectors expressing a foreign antigen are under intense development for these and other indications. One of the most advanced and most promising vectors is the attenuated, non-replicating poxvirus MVA (modified vaccinia virus Ankara), a safer derivative of the uniquely successful smallpox vaccine. Despite the ability of recombinant MVA to induce potent humoral and cellular immune responses against transgenic antigen in humans, especially when used as the latter element of a heterologous prime-boost regimen, doubts are occasionally expressed about the ultimate feasibility of this approach. In this review, five common misconceptions over recombinant MVA are discussed, and evidence is cited to show that recombinant MVA is at least sufficiently genetically stable, manufacturable, safe, and immunogenic (even in the face of prior anti-vector immunity) to warrant reasonable hope over the feasibility of large-scale deployment, should useful levels of protection against target pathogens, or therapeutic benefit for cancer, be demonstrated in efficacy trials.