A narrative review of the impact of ultraviolet radiation and sunscreen on the skin microbiome

BACKGROUND

The human skin microbiome is a dynamic ecosystem that plays an important role in skin health. The skin microbiome has been implicated in numerous diseases, and our knowledge surrounding it continues to evolve. A better understanding of the interactions between the environment and the skin microbiome will lead to improvements in skin health.

METHODS

This article reviews the published literature surrounding the impact of ultraviolet radiation (UVR) and sunscreen on the skin microbiome.

RESULTS

Skin microbes are differentially impacted by UVR, and alterations in the microbiome can be detected following UVR exposure. These changes are related to direct bactericidal effects, alterations in the cutaneous metabolome, and changes in the cutaneous immune system. UV filters used in sunscreen have been shown to have bactericidal effects, and many compounds used in sunscreen emulsions can also negatively impact cutaneous microbes.

CONCLUSION

A healthy microbiome has been shown to produce compounds that help protect the skin from UVR, and sunscreen has the potential to reduce the diversity of the skin microbiome. This indicates that designing sunscreen products that both provide protection against UVR and preserve the skin microbiome may offer additional benefits to skin health when compared with traditional sunscreen products.

Practical guidelines for the treatment of vitiligo with the melanocyte-keratinocyte transplantation procedure

Vitiligo manifests as depigmented macules and patches on the skin and can significantly impact a patient's quality of life. Despite the availability of several treatment modalities, rates of repigmentation can vary widely among individuals and disease subtypes. For patients with stable vitiligo who have not achieved satisfactory results with medical treatments, the melanocyte-keratinocyte transplantation procedure (MKTP) is a viable option. While variations of this autologous non-cultured cellular grafting procedure are performed by dermatologic surgeons worldwide and has shown good tolerability and effectiveness, it remains under utilized in the United States. We present a comprehensive overview of MKTP, highlighting evidence-based and practical techniques to enhance patient outcomes. By serving as a valuable resource, this review aims to support dermatologic surgeons seeking to incorporate MKTP into their practice and promote awareness regarding its benefits, ultimately fostering a more comprehensive approach to vitiligo care.

The development of non-scarring alopecia in women who wear the hijab

Little is known about hair loss associated with wearing the hijab, a religious head covering worn by Muslim women. We performed a single-center analysis to investigate the association between various forms of non-scarring alopecia and wearing the hijab. This study included 125 patients who wore the hijab and 40 race/ethnicity-matched women who did not wear the hijab. Among the 165 total patients diagnosed between January 2015 and March 2022, 71 had telogen effluvium, 78 had female pattern hair loss, and 16 had traction alopecia. We found patients who wore the hijab had a younger mean age of alopecia onset than patients who did not wear the hijab (31.5 vs. 37.3 years; P = 0.02). Our study suggests that vitamin D deficiency (OR 4.1; 95% CI 1.2-14.1; P = 0.02) and seborrheic dermatitis (OR 2.9; 95% CI 1.1-8.1; P = 0.03) may significantly impact the development of telogen effluvium in patients who wear the hijab. Targeting these risk factors among patients who wear the hijab may be considered to prevent hair loss.

Optimisation of skin phototype classification

Understanding individuals' skin pigmentation and photosensitivity is important in judging risk of skin cancer and response to certain treatment modalities. However, individuals with darkly pigmented skin are poorly represented in the widely used Fitzpatrick skin phototype (FST) system. Moreover, the FST system is prone to misuse, as it relies on subjective patient and clinician assessment of skin type, and does not clearly differentiate pigmentation from photosensitivity. By evaluating the key literature surrounding the FST system, its criticisms and proposed alternatives, this review serves to understand how skin phototype classification can be optimised.

A method for assessing rater reliability in applying the Vitiligo Area Scoring Index

The Vitiligo Area Scoring Index (VASI) is a tool for measuring repigmentation after patients undergo vitiligo treatment, offering a standardized, quantitative scale without the need for specialized equipment. For large multicentre trials that require multiple raters, VASI must be consistently applied to generate interpretable data; therefore, a method for assessing rater reliability would improve data integrity for large clinical studies of vitiligo. This study aimed to assess a method for determining the reliability of VASI raters by evaluating raters of different levels of experience relative to a gold standard.

The effects of UV filters on health and the environment

Sunscreens are an important means of protection against sunburns, dyspigmentation, photoaging, and photocarcinogenesis. Sunscreens come in a variety of formulations that can protect against ultraviolet B (UVB) radiation, both UVB and ultraviolet A (UVA) radiation (broad-spectrum sunscreens), and UVB, UVA, and visible light (tinted broad-spectrum sunscreens). In the USA, there is currently a paucity of FDA-approved broad-spectrum filters on the market. Studies have identified the presence of multiple UV filters in water sources globally. Many laboratory studies have implicated the potential impact of UV filters on coral reef bleaching, the food chain, and human health. However, many of these studies are performed at concentrations that are much higher than those present in the natural environment. With increasing discussion surrounding the role of organic and inorganic UV filters as potential environmental pollutants over the past decade, approval of additional broad-spectrum filters would be an important means of alleviating the use of more controversial filters. The aim of this article is to review the effects of UV filters on health and the environment and explore potential adjunctive agents for photoprotection.

Recipient-to-Donor Ratios in the Surgical Treatment of Vitiligo, Leukoderma, and Piebaldism: A Retrospective Review

BACKGROUND

The autologous noncultured melanocyte keratinocyte transplant procedure (MKTP) has emerged as a popular grafting technique with proven efficacy for achieving repigmentation. However, there remains no consensus regarding the optimal recipient-to-donor (RD) ratio required to achieve acceptable repigmentation. In this retrospective cohort study of 120 patients, we sought to examine whether expansion ratios impact the repigmentation success rates following MKTP.

RESULTS

A total of 69 patients (mean [SD] age was 32.4 [14.3] years, mean follow-up was 30.4 [22.5] months, 63.8% were male; 55% were dark-skinned individuals [Fitzpatrick IV-VI]) were included. The mean percent change in the Vitiligo Area Scoring Index (VASI) was 80.2 (±23.7; RD of 7.3) in patients with focal/segmental vitiligo (SV), 58.3 (±33.0; RD of 8.2) in those with non-segmental vitiligo (NSV), and 51.8 (±33.6; RD of 3.7) in those with leukoderma and piebaldism. Focal/SV was positively associated with a higher percent change in VASI (parameter estimate: 22.6, p value <0.005). In the SV/focal group, non-white patients had a higher RD ratio compared to White individuals (8.2 ± 3.4 vs. 6.0 ± 3.1, respectively, p value = 0.035).

DISCUSSION

In our study, we found that patients with SV were significantly more likely to achieve higher repigmentation rates compared to those with NSV. Although repigmentation rates were higher in the low expansion ratio group than in the high expansion ratio group, we did not observe a significant difference between the two groups.

CONCLUSION

MKTP is an effective therapy for restoring repigmentation in patients with stable vitiligo. Therapeutic response of vitiligo to MKTP appears to be influenced by the type of vitiligo, rather than a specific RD ratio.

Targeting Tyrosinase in Hyperpigmentation: Current Status, Limitations and Future Promises

Hyperpigmentation is a common and distressing dermatologic condition. Since tyrosinase (TYR) plays an essential role in melanogenesis, its inhibition is considered a logical approach along with other therapeutic methods to prevent the accumulation of melanin in the skin. Thus, TYR inhibitors are a tempting target as the medicinal and cosmetic active agents of hyperpigmentation disorder. Among TYR inhibitors, hydroquinone is a traditional lightening agent that is commonly used in clinical practice. However, despite good efficacy, prolonged use of hydroquinone is associated with side effects. To overcome these shortcomings, new approaches in targeting TYR and treating hyperpigmentation are desperately requiredessentialneeded. In line with this purpose, several non-hydroquinone lightening agents have been developed and suggested as hydroquinone alternatives. In addition to traditional approaches, nanomedicine and nanotheranostic platforms have been recently proposed in the treatment of hyperpigmentation. In this review, we discuss the available strategies for the management of hyperpigmentation with a focus on TYR inhibition. In addition, alternative treatment options to hydroquinone are discussed. Finally, we present nano-based strategies to improve the therapeutic effect of drugs prescribed to patients with skin disorders.

Systemic therapies in vitiligo: a review

Vitiligo is characterized by the development of depigmented macules and patches. Autoimmunity has been established as a factor in disease pathogenesis, leading to utilization of immunosuppressive agents. Topical immunosuppressants are commonly used; however, this treatment modality is often cumbersome and inefficient, as many patients have active disease with extensive body surface area involvement. Prompt and aggressive treatment of vitiligo is important, as this may prevent progression and improve quality of life. To meet these challenges and improve patient outcomes, interest in systemic therapies has grown. Currently, oral therapies are rarely prescribed, likely due to concerns with systemic side effects and unclear efficacy. This article provides a brief overview on the use of systemic agents in treating vitiligo in order to provide additional therapeutic options to clinicians.

Demographics and clinical presentations of 844 patients with light and dark skin types with polymorphous light eruption and chronic actinic dermatitis evaluated over 23 years

INTRODUCTION

Polymorphous light eruption (PMLE) and chronic actinic dermatitis (CAD) have been classically described in White individuals, although recent studies have reported higher prevalence in patients with dark skin types, particularly African Americans.

OBJECTIVE

To evaluate for differences in demographic, and clinical features between persons with light and dark skin types who have PMLE and CAD.

METHODS

Retrospective review of patients with PMLE and CAD who were diagnosed from January 1, 1998, through November 31, 2021, at a single academic dermatology center.

RESULTS/DISCUSSION

A total of 844 patients (725 [85.9%] female; mean [SD] age of onset: 41.7 [16.9] years) were diagnosed with PMLE, and 60 patients (22 [36.6%] female; mean age, [SD]: 60.6 [10.6] years) of age at presentation, disease duration of 8.2 [7.3] years were diagnosed with CAD. Although just over 50% of the general clinic population was White, the prevalence of PMLE and CAD was significantly higher in dark-skinned individuals compared to light-skinned individuals (PMLE: 625 [74.0%] vs. 219 [25.9%], p value < .001; CAD: 43 [71.6%] vs. 17 [28.3%], p value = .003) respectively. The pinpoint papular variant of PMLE (PP-PMLE) was predominantly seen in dark-skinned individuals.

CONCLUSION

A substantial proportion of PMLE and CAD cases are present in dark-skinned individuals. PP-PMLE can be mistaken for lichen nitidus. As such, recognition of this entity is important for adequate evaluation and management of patients with PMLE.

Disorders of hyperpigmentation. Part II. Review of management and treatment options for hyperpigmentation

Key challenges in the management of pigmentary disorders such as melasma and postinflammatory hyperpigmentation are their resistance to treatment, tendency to recur after treatment, and the risk of exacerbating hyperpigmentation with many treatment modalities. The second article in this 2-part continuing medical education series on pigmentary disorders focuses on the evidence behind medical and procedural treatments of dyschromias, including photoprotection, topical lightening agents, oral agents, chemical peels, and laser therapy.

Disorders of hyperpigmentation. Part I. Pathogenesis and clinical features of common pigmentary disorders

Disorders of hyperpigmentation are common and, depending on the extent and location of involvement, can affect the quality of life and pose a significant psychologic burden for patients. Given the similarities in presentation of the various causes of hyperpigmentation, it is often difficult to elucidate the etiology of these conditions, which is important to guide management. Furthermore, certain disorders, such as lichen planus pigmentosus and ashy dermatosis, have similar clinical and/or histologic presentations, and their classification as distinct entities has been debated upon, leading to additional confusion. In this review, the authors selected commonly encountered disorders of hyperpigmentation of the skin, subdivided into epidermal, dermal, or mixed epidermal-dermal disorders based on the location of pigment deposition, along with disorders of hyperpigmentation of the mucosa and nails. Melanocytic nevi, genetic disorders, and systemic causes of hyperpigmentation were largely excluded and considered to be outside the scope of this review. We discussed the pathogenesis of hyperpigmentation as well as the clinical and histologic features of these conditions, along with challenges encountered in their diagnosis and classification. The second article in this 2-part continuing medical education series focuses on the medical and procedural treatments of hyperpigmentation.

Dermatological considerations and culturally sensitive recommendations for women who wear the hijab

Currently, there is little guidance in the literature on how to advise patients who wear the hijab on hijab-related dermatoses. This manuscript describes hijab-related dermatoses and provides culturally sensitive recommendations that can be used in conjunction with standard treatments to provide more holistic care for these patients.

A Focused review on the pathophysiology of post-inflammatory hyperpigmentation

Post-inflammatory hyperpigmentation (PIH) is one of the most common disorders of acquired hyperpigmentation. It often develops following cutaneous inflammation and is triggered by various stimuli, from inflammatory and autoimmune conditions to iatrogenic causes and mechanical injuries. While it is well established that an increase in melanin production and distribution within the epidermis and dermis is a hallmark feature of this condition, the exact mechanisms underlying PIH are not completely understood. This article aims to review the current evidence on the pathophysiology of PIH as the cellular and molecular mechanism of PIH represents a promising avenue for the development of novel, targeted therapies.

Photoprotection by clothing: A review

Clothing is recognized by leading health agencies as a primary method to protect against the harmful effects of photodamage caused by ultraviolet (UV) radiation and visible light. The photoprotective capacity of clothing is commonly measured as the ultraviolet protective factor (UPF). While the technology driving photoprotective clothing has been well-established, there continues to be efforts to discover new materials to improve the UPF of clothing. Here, we show increased Google searches for photoprotective clothing over the last decade, suggesting a high level of public interest in photoprotective clothing. In addition, we investigate the frequency of UPF-graded photoprotective clothing sold by large retail stores featured in Fortune 1000. We review factors that alter the UPF of clothing and describe emerging textile technologies used to increase clothing's photoprotective capacity. Finally, we compare how photoprotective clothing is regulated among different countries, the importance of photoprotective clothing in occupational health, and research in visible light and clothing photoprotection.

Applying to dermatology residency without a home program: Advice to medical students in the COVID-19 pandemic and beyond

Dermatology has historically been one of the most competitive residencies to match into. One commonly overlooked factor is the importance of having mentors in the field, as they have experience guiding successful applicants and can provide great insight into what residency programs are looking for. Given that many students without home dermatology programs may struggle to find mentors in the field, we share advice on how these students can obtain the mentorship and guidance needed to match into dermatology.

Sunscreens and Photoaging: A Review of Current Literature

Sunscreens have been on the market for many decades as a means of protection against ultraviolet-induced erythema. Over the years, evidence has also shown their efficacy in the prevention of photoaging, dyspigmentation, DNA damage, and photocarcinogenesis. In the USA, most broad-spectrum sunscreens provide protection against ultraviolet B (UVB) radiation and short-wavelength ultraviolet A (UVA) radiation. Evidence suggests that visible light and infrared light may play a role in photoaging and should be considered when choosing a sunscreen. Currently, there is a paucity of US FDA-approved filters that provide protection against long UVA (> 370 nm) and none against visible light. Additionally, various sunscreen additives such as antioxidants and photolyases have also been reported to protect against and possibly reverse signs of photoaging. This literature review evaluates the utility of sunscreen in protecting against photoaging and further explores the requirements for an ideal sunscreen.

An in vivo model of postinflammatory hyperpigmentation and erythema: clinical, colorimetric and molecular characteristics

BACKGROUND

Postinflammatory hyperpigmentation (PIH) is a common, acquired pigmentary disorder of the skin associated with significant quality-of-life impairment, especially in individuals with skin of colour. Current treatment for PIH is limited, largely due to a poor understanding of disease pathogenesis and the lack of a representative disease model.

OBJECTIVES

This study is intended to further develop, update and validate our previously designed in vivo model of acne-induced PIH/postinflammatory erythema (PIE) using different concentrations of trichloroacetic acid (TCA), a medium-depth chemical peel.

METHODS

Twenty-nine patients with skin types II-VI and clinician-confirmed presence of two or more truncal acne pustules and PIH/PIE were included. On the basis of Investigator's Global Assessment (IGA), clinical polarized photography (CPP), colorimetry and Skindex, we experimentally determined an optimum TCA concentration and assessed our model's ability to exhibit a dose-response relationship between degree of inciting insult and severity of resulting pigmentation. We also performed differential microRNA profiling and pathway analysis to explore the potential of microRNAs as molecular adjuncts to our model.

RESULTS

Application of TCA 30% produced lesions indistinguishable from acne-induced PIH and PIE lesions on the basis of colorimetry data without causing epidermal necrosis. Application of progressively increasing TCA doses from 20% to 30% resulted in concentration-dependent increases in CPP, IGA and colorimetry scores at all timepoints during the study. miRNA-31 and miRNA-23b may play a role in PIH pathogenesis, although further validation is required.

CONCLUSIONS

Our TCA-based in vivo model, using TCA concentrations between 20% and 30% with an optimum of 30%, enables the quantitative assessment of the pigmentary response to varying degrees of cutaneous inflammation in a fashion that mirrors natural acne-induced PIH and PIE.

The Etiquettes of Hijab: Recommendations to Improve Care in Dermatology Clinics

A strong physician-patient relationship is the foundation of providing excellent patient care, as it improves providers' job satisfaction and patients' confidence, which influences their health outcomes.^1,2 Strong relationships also prompt more accurate identification of patients' needs and perceptions, which may be used as an indicator of physician competence.³ Given the diverse racial, cultural, and religious backgrounds of patients, it is imperative for physicians to have a fundamental understanding of different cultures in order to provide the best care for patients.

Quantitative measurement of skin surface oiliness and shine using differential polarized images

Excess amounts of skin surface oil can lead to adverse psychological consequences. Grease-spot photometry-based techniques measure sebum production rate. However, besides being tedious, these measurements are influenced by contact area, applied pressure, and time of application. Image analysis of polarized images has the potential to provide objective, quantitative information of skin oiliness. This study was designed to set up an imaging device for capturing and enhancing the changes in skin surface oiliness and to clinically and quantitatively, (via image analysis), evaluate varying levels of skin surface oiliness. Mineral oil was used to simulate skin surface oil. 40.5 µL of the mineral oil was applied within a two inch square area of interest on facial skin in twelve steps, from 1 to 40.5 µL, at 40% increments. The results indicate a strong correlation between the quantitative skin surface oiliness measurements and the clinical assessments. This sensitive technique has the potential to be utilized in future studies to evaluate product efficacies in reducing skin oiliness.

The Role of Sunscreen in Melasma and Postinflammatory Hyperpigmentation

Photosensitive conditions such as melasma and postinflammatory hyperpigmentation (PIH) are exacerbated by exposure to ultraviolet (UV) rays and visible light making sunscreen use an essential component of treatment. This is especially true in skin of color patients who are less likely to use photoprotection, even if diagnosed with these photoexacerbated conditions. We aimed to evaluate the body of literature to provide evidence for the use of sunscreen in the treatment of melasma and PIH. We reviewed English articles from PubMed, Journals@Ovid Full Text, and Embase using the search terms “sunscreen” and either “melasma” “PIH,” or “post-inflammatory hyperpigmentation.” Nine relevant publications provide evidence that a broad spectrum of protection, including UVA, UVB, and visible light within sunscreens can play an adjuvant role in therapy for melasma and PIH by stabilizing and improving these pigmentary disorders in skin of color patients. This review illustrates the advantages and limitations of sunscreen use, as well as practice gaps in photoprotection in the skin of color patients with melasma and PIH.

Oral Polypodium Leucotomos Extract and Its Impact on Visible Light-Induced Pigmentation in Human Subjects

BACKGROUND: Visible light (VL) has multiple effects on the skin that currently available sunscreens do not protect against. Polypodium leucotomos extract (PLE) has properties that may offer protection against VL. OBJECTIVES: To determine the effectiveness of PLE in preventing VL-induced effects. METHODS: Twenty-two subjects with Fitzpatrick skin phototype IV-VI were enrolled. On day 0, subjects were irradiated with VL. Clinical Investigator’s Global Assessment (IGA) scoring and spectroscopic evaluations were performed immediately, 24 hours, and 7 days after irradiation. Subjects then received a 28-day supply of PLE (480 mg daily). Irradiation and evaluation were repeated. Three 4-mm punch biopsies were obtained for immunohistochemistry analysis: one from normal unirradiated skin and the other two twenty-four hours after irradiation, pre- and post-PLE, from sites irradiated with highest dose of VL. RESULTS: All subjects had immediate pigment darkening, persistent pigment darkening, and delayed tanning both pre- and post-PLE. For the highest VL dose (480 J/cm²) spectroscopic assessments demonstrated a statistically significant decrease in persistent pigment darkening and delayed tanning post-PLE. In addition, there was a significant decrease in cyclooxygenase-2, and a trend towards decreases in the markers for cellular damage post-PLE. While there was a trend towards lower IGA scores post-PLE, statistical significance was not reached possibly due to lack of sensitivity of the visual IGA scoring system in detecting small changes. CONCLUSIONS: Spectroscopic data and immunohistochemistry indicate an effect of PLE on visible light induced effects. As such, PLE may be used as an adjuvant to traditional means of photoprotection to protect against the effects of VL. Clinical trial registration number: NCT02904798. J Drugs Dermatol. 2019;18(12):1198-1203.

Poikiloderma with neutropenia and associated squamous cell carcinoma: A case report

Here, we describe a case of a patient with known poikiloderma with neutropenia who developed cutaneous squamous cell carcinoma in a chronically sun-exposed area at the age of 14. To date, there is only one other report of this association. This report highlights the need for routine skin cancer screening in patients with this diagnosis as well as the importance of a correct initial diagnosis.

A Comparative Analysis of Electric and Radiofrequency Microneedling Devices on the Market

Microneedling was first described in 1995 by Orentreich and Orentreich for the treatment of atrophic scars and wrinkles.¹ The local injury induced by dermal penetration of microneedling causes release of growth factors such as transforming growth factor (TGF)-α, TGF-β, and platelet-derived growth factor (PDGF). This stimulates collagen and elastin fiber production as well as capillary formation, ultimately leading to tissue remodeling.².

Vitiligo Surgery: Shuffling Melanocytes

Vitiligo is a disorder characterized by the development of depigmented macules and patches secondary to melanocyte destruction. Several treatment options are available, including medical, light-based, and surgical therapies, that are often used in combination to achieve maximal repigmentation. Vitiligo surgery is an effective yet underperformed treatment, mainly because of lack of awareness and availability. The purpose of this article is to review one method of vitiligo surgery, the melanocyte-keratinocyte transplantation procedure, and discuss its utility in treating vitiligo.

The Vitiligo Working Group recommendations for narrowband ultraviolet B light phototherapy treatment of vitiligo

BACKGROUND

Treatment of vitiligo with narrowband ultraviolet B light (NBUVB) is an important component of the current standard of care. However, there are no consistent guidelines regarding the dosing and administration of NBUVB in vitiligo, reflected by varied treatment practices around the world.

OBJECTIVE

To create phototherapy recommendations to facilitate clinical management and identify areas requiring future research.

METHODS

The Vitiligo Working Group (VWG) Phototherapy Committee addressed 19 questions regarding the administration of phototherapy over 3 conference calls. Members of the Photomedicine Society and a group of phototherapy experts were surveyed regarding their phototherapy practices.

RESULTS

Based on comparison and analysis of survey results, expert opinion, and discussion held during conference calls, expert recommendations for the administration of NBUVB phototherapy in vitiligo were created.

LIMITATIONS

There were several areas that required further research before final recommendations could be made. In addition, no standardized methodology was used during literature review and to assess the strength of evidence during the development of these recommendations.

CONCLUSION

This set of expert recommendations by the VWG is based on the prescribing practices of phototherapy experts from around the world to create a unified, broadly applicable set of recommendations on the use of NBUVB in vitiligo.

Antigenic diversification is correlated with increased thermostability in a mammalian virus

The theory of plastogenetic congruence posits that ultimately, the pressure to maintain function in the face of biomolecular destabilization produces robustness. As temperature goes up so does destabilization. Thus, genetic robustness, defined as phenotypic constancy despite mutation, should correlate with survival during thermal challenge. We tested this hypothesis using vesicular stomatitis virus (VSV). We produced two sets of evolved strains after selection for higher thermostability by either preincubation at 37°C or by incubation at 40°C during infection. These VSV populations became more thermostable and also more fit in the absence of thermal selection, demonstrating an absence of tradeoffs. Eleven out of 12 evolved populations had a fixed, nonsynonymous substitution in the nucleocapsid (N) open reading frame. There was a partial correlation between thermostability and mutational robustness that was observed when the former was measured at 42°C, but not at 37°C. These results are consistent with our earlier work and suggest that the relationship between robustness and thermostability is complex. Surprisingly, many of the thermostable strains also showed increased resistance to monoclonal antibody and polyclonal sera, including sera from natural hosts. These data suggest that evolved thermostability may lead to antigenic diversification and an increased ability to escape immune surveillance in febrile hosts, and potentially to an improved robustness. These relationships have important implications not only in terms of viral pathogenesis, but also for the development of vaccine vectors and oncolytic agents.