Downregulation of CD46 During Muscle Differentiation: Implications for Gene Transfer to Human Skeletal Muscle Using Group B Adenoviruses

Seroprevalence of Binding and Neutralizing Antibodies against 39 Human Adenovirus Types in Patients with Neuromuscular Disorders

High pre-existing antibodies against viral vectors reduce their functionality and may lead to adverse complications. To circumvent this problem in future gene therapy approaches, we tested the seroprevalence of a large range of human adenovirus types in patients with neuromuscular disorders (NMDs) to find appropriate viral vector candidates for gene replacement therapy for NMDs. Binding and neutralizing antibodies against 39 human adenovirus types were tested in the sera of 133 patients with NMDs and 76 healthy controls aged 17-92 years. The influence of age, sex, and NMDs on antibody levels was analyzed. The seroprevalence of different adenoviruses in the cohort varied widely. The highest levels of binding antibodies were detected against HAdV-D27, -C1, -D24, -D70, -B14, -C6, -D13, -B34, and -E4, whereas the lowest reactivity was detected against HAdV-F41, -A31, -B11, -D75, -D8, -D65, -D26, -D80, and -D17. The highest neutralizing reactivity was observed against HAdV-B3, -C2, -E4, -C1, -G52, -C5, and -F41, whereas the lowest neutralizing reactivity was observed against HAdV-D74, -B34, -D73, -B37, -D48, -D13, -D75, -D8, -B35, and -B16. We detected no influence of sex and only minor differences between different age groups. Importantly, there were no significant differences between healthy controls and patients with NMDs. Our data show that patients with NMDs have very similar levels of binding and neutralizing antibodies against HAdV compared to healthy individuals, and we identified HAdV-A31, -B16, -B34, -B35, -D8, -D37, -D48, -D73, -D74, -D75, and -D80 as promising candidates for future vector development due to their low binding and neutralizing antibody prevalence.

Insights into the immune responses of SARS-CoV-2 in relation to COVID-19 vaccines

The three types of approved coronavirus disease 2019 (COVID-19) vaccines that have been emergency-use listed (EUL) by the World Health Organization are mRNA vaccines, adenovirus-vectored vaccines, and inactivated vaccines. Canonical vaccine developments usually take years or decades to be completed to commercialization; however, the EUL vaccines being used in the current situation comprise several COVID-19 vaccine candidates applied in studies and clinical settings across the world. The extraordinary circumstances of the COVID-19 pandemic have necessitated the emergency authorization of these EUL vaccines, which have been rapidly developed. Although the benefits of the EUL vaccines outweigh their adverse effects, there have been reports of rare but fatal cases directly associated with COVID-19 vaccinations. Thus, a reassessment of the immunological rationale underlying EUL vaccines in relation to COVID-19 caused by SARSCOV-2 virus infection is now required. In this review, we discuss the manifestations of COVID-19, immunologically projected effects of EUL vaccines, reported immune responses, informed issues related to COVID-19 vaccination, and the potential strategies for future vaccine use against antigenic variants.

Adenovirus vector-based vaccine for infectious diseases

Replication-incompetent adenovirus (Ad) vectors have been widely used as gene delivery vehicles in both gene therapy studies and basic studies for gene function analysis due to their highly advantageous properties, which include high transduction efficiencies, relatively large capacities for transgenes, and high titer production. In addition, Ad vectors induce moderate levels of innate immunity and have relatively high thermostability, making them very attractive as potential vaccine vectors. Accordingly, it is anticipated that Ad vectors will be used in vaccines for the prevention of infectious diseases, including Ebola virus disease and acquired immune deficiency syndrome (AIDS). Much attention is currently focused on the potential use of an Ad vector vaccine for coronavirus disease 2019 (COVID-19). In this review, we describe the basic properties of an Ad vector, Ad vector-induced innate immunity and immune responses to Ad vector-produced transgene products. Development of novel Ad vectors which can overcome the drawbacks of conventional Ad vector vaccines and clinical application of Ad vector vaccines to several infectious diseases are also discussed.

Mutant myogenin promoter-controlled oncolytic adenovirus selectively kills PAX3-FOXO1-positive rhabdomyosarcoma cells

The PAX3-FOXO1 fusion gene functions as a transactivator and increases expression of many cancer-related genes. These lead to metastases and other unfavorable outcomes for alveolar rhabdomyosarcoma (ARMS) patients. In order to target ARMS with the PAX3-FOXO1 transactivator, we developed an Oncolytic Adenovirus (OAd) regulated by the myogenin (pMYOG) promoter with a mutation in the Myocyte Enhancer Factor-2 binding site (mMEF2) in this study. The expression of MYOG in the two RMS cell lines (Rh30; PAX3-FOXO1-positive, RD; PAX3-FOXO1-negative) is about 1,000 times higher than normal skeletal muscle cell (SkMC). Ad5/3-pMYOG(S)-mMEF2 (short-length pMYOG-controlled OAd with mMEF2) showed strong replication and cytocidal effect in Rh30, but to a much lesser extent in RD. Ad5/3-pMYOG(S) (pMYOG-controlled OAd with native pMYOG) showed similar effects in RD and Rh30. Neither virus killed SkMC, indicating that Ad5/3-pMYOG(S)-mMEF2 selectively replicates and kills cells with PAX3-FOXO1. Additionally, Ad5/3-pMYOG(S)-mMEF2 showed replication and spread in vitro as well as tumor growth suppression and intratumoral viral spread in vivo, selectively in Rh30 not in RD. Our findings revealed that Ad5/3-pMYOG(S)-mMEF2 shows a promise as a safe and potent therapy to improve treatment in PAX3-FOXO1-positive ARMSs.

Gene therapy for cardiovascular disease: perspectives and potential

Cardiovascular disease is the most frequent cause of mortality in the western world, accounting for over 800,000 premature deaths per year in the EU alone. Cardiovascular disease is the second most common application for gene therapy clinical trials, which most frequently employ adenovirus serotype 5 (Ad5)-based vectors as delivery vehicles. Although interactions of Ad5 vectors with circulating proteins and cells can limit their efficacy after systemic administration, local gene delivery strategies show great potential in the cardiovascular setting, notably in the context of vascular delivery. Here we review the pathogenesis of bypass graft failure and in-stent restenosis, identifying potential therapeutic targets and discussing recent advances in the field of adenovirus biology and retargeting that, in concert, will potentially translate in coming years to more effective gene therapies for cardiovascular applications.

Modulation of coxsackie and adenovirus receptor expression for gene transfer to normal and dystrophic skeletal muscle

BACKGROUND

Efficient adenovirus (AdV)-mediated gene transfer is possible only in immature muscle or regenerating muscle, suggesting that a developmentally regulated event plays a major role in limiting AdV uptake in mature skeletal muscle. Previously, we showed that the expression of the primary coxsackie and adenovirus receptor (CAR) is severely down-regulated during muscle maturation and that, in muscle-specific CAR transgenic mice, there is significant enhancement of AdV-mediated gene transfer to mature skeletal muscle.

METHODS

To evaluate whether increasing CAR expression can also augment gene transfer to dystrophic muscle that has many regenerating fibers, we crossed CAR transgenics with dystrophin-deficient mice (mdx/CAR). We also tested a two-step protocol in which CAR levels were increased in the target muscle, prior to administration of AdV, through the use of recombinant adeno-associated virus (AAV2) expressing CAR. Lastly, we assessed the effect of histone deacetylase inhibitors on CAR and AdV transduction efficiency in myoblasts and mdx muscle.

RESULTS

Although somewhat higher rates of transduction can be achieved in adult mdx mice than in normal mice as a result of ongoing muscle regeneration in these animals, CAR expression in the mdx background (mdx/CAR transgenics) still markedly improved the susceptibility of mature muscle to AdV-mediated gene transfer of dystrophin. Prior administration of AAV2-CAR to normal muscle led to significantly increased transduction by subsequent injection of AdV. The histone deacetylase inhibitor valproate increased CAR transcript and protein levels in myoblasts and mdx muscle, and also increased AdV-mediated gene transfer.

CONCLUSIONS

We have developed a method of increasing CAR levels in both normal and regenerating muscle.

Dilated cardiomyopathy alters the expression patterns of CAR and other adenoviral receptors in human heart

Gene therapy trials for heart failure have demonstrated the key role of efficient gene transfer in achieving therapeutic efficacy. An attractive approach to improve adenoviral gene transfer is to use alternative virus serotypes with modified tropism. We performed a detailed analysis of cardiac expression of receptors for several adenovirus serotypes with a focus on differential expression of CAR and CD46, as adenoviruses targeting these receptors have been used in various applications. Explanted hearts from patients with DCM and healthy donors were analyzed using Q-RT-PCR, western blot and immunohistochemistry. Q-RT-PCR and Western analyses revealed robust expression of all receptors except CD80 in normal hearts with lower expression levels in DCM. Immunohistochemical analyses demonstrated that CD46 expression was somewhat higher than CAR both in normal and DCM hearts with highest levels of expression in intramyocardial coronary vessels. Total CAR expression was upregulated in DCM. Triple staining on these vessels demonstrated that both CAR and CD46 were confined to the subendothelial layer in normal hearts. The situation was clearly different in DCM, where both CAR and CD46 were expressed by endothelial cells. The induction of expression of CAR and CD46 by endothelial cells in DCM suggests that viruses targeting these receptors could more easily gain entry to heart cells after intravascular administration. This finding thus has potential implications for the development of targeted gene therapy for heart failure.