Smallpox: the basics

Viral infection and antiviral immunity in the oral cavity

Individual tissues have distinct antiviral properties garnered through various mechanisms, including physical characteristics, tissue-resident immune cells and commensal organisms. Although the oral mucosa has long been appreciated as a critical barrier tissue that is exposed to a continuous barrage of pathogens, many fundamental aspects of the antiviral immune response in this tissue remain unknown. Several viral pathogens, such as herpesviruses and human papillomaviruses, have been acknowledged both historically and at present for infections in the oral cavity that result in substantial clinical burden. However, recent viral outbreaks, including those with SARS-CoV-2 and mpox, featured oral symptoms even though these viruses are not generally considered oral pathogens. Ensuing studies have shown that the oral cavity is an important locale for viral infection and potential transmission of newly emergent or re-emergent pathogens, highlighting the need for an increased understanding of the mechanisms of antiviral immunity at this site. In this Review, we provide a broad overview of antiviral immune responses in the oral cavity and discuss common viral infections and their manifestations in the oral mucosa. In addition, we present current mouse models for the study of oral viral infections.

Mimics of Monkeypox: Considerations for the emergency medicine clinician

INTRODUCTION

Mpox, formerly known as monkeypox, is a public health emergency most commonly presenting with a painful rash and several systemic findings. However, there are several conditions that may mimic its presentation.

OBJECTIVE

This narrative review provides a focused overview of mpox mimics for emergency clinicians.

DISCUSSION

Mpox is a global health emergency. The disease is primarily spread through contact, followed by the development of a centrifugally-spread rash that evolves from macules to papules to vesicles to pustules. This is often associated with lymphadenopathy and fever. As the rash is one of the most common presenting signs of the infection, patients mpox may present to the emergency department (ED) for further evaluation. There are a variety of mimics of mpox, including smallpox, varicella, primary and secondary syphilis, acute retroviral syndrome, and genital herpes simplex virus.

CONCLUSION

Knowledge of mpox and its mimics is vital for emergency clinicians to differentiate these conditions and ensure appropriate diagnosis and management.

Cowpox Viruses: A Zoo Full of Viral Diversity and Lurking Threats

Cowpox viruses (CPXVs) exhibit the broadest known host range among the Poxviridae family and have caused lethal outbreaks in various zoo animals and pets across 12 Eurasian countries, as well as an increasing number of human cases. Herein, we review the history of how the cowpox name has evolved since the 1700s up to modern times. Despite early documentation of the different properties of CPXV isolates, only modern genetic analyses and phylogenies have revealed the existence of multiple Orthopoxvirus species that are currently constrained under the CPXV designation. We further chronicle modern outbreaks in zoos, domesticated animals, and humans, and describe animal models of experimental CPXV infections and how these can help shaping CPXV species distinctions. We also describe the pathogenesis of modern CPXV infections in animals and humans, the geographic range of CPXVs, and discuss CPXV-host interactions at the molecular level and their effects on pathogenicity and host range. Finally, we discuss the potential threat of these viruses and the future of CPXV research to provide a comprehensive review of CPXVs.

Low-Temperature Multiple Micro-Dispensing on Microneedles for Accurate Transcutaneous Smallpox Vaccination

Smallpox is an acute contagious disease caused by the variola virus. According to WHO guidelines, the smallpox vaccine is administrated by scarification into the epidermis using a bifurcated needle moistened with a vaccine solution. However, this invasive vaccination method involving multiple skin punctures requires a special technique to inoculate, as well as a cold chain for storage and distribution of vaccine solutions containing a live virus. Here, we report a transcutaneous smallpox vaccination using a live vaccinia-coated microneedle (MN) patch prepared by a low-temperature multiple nanoliter-level dispensing system, enabling accurate transdermal delivery of live vaccines and maintenance of bioactivity. The live vaccinia in hyaluronic acid (HA) solutions was selectively coated on the solid MN tips, and the coating amount of the vaccine was precisely controlled through a programmed multiple dispensing process with high accuracy under low temperature conditions (2–8 °C) for smallpox vaccination. Inoculation of mice (BALB/C mouse) with the MN patch coated with the second-generation smallpox vaccine increased the neutralizing antibody titer and T cell immune response. Interestingly, the live vaccine-coated MN patch maintained viral titers at −20 °C for 4 weeks and elevated temperature (37 °C) for 1 week, highlighting improved storage stability of the live virus formulated into coated MN patches. This coated MN platform using contact dispensing technique provides a simple and effective method for smallpox vaccination.

Imaging viral infection in vivo to gain unique perspectives on cellular antiviral immunity

The past decade has seen near continual global public health crises caused by emerging viral infections. Extraordinary increases in our knowledge of the mechanisms underlying successful antiviral immune responses in animal models and during human infection have accompanied these viral outbreaks. Keeping pace with the rapidly advancing field of viral immunology, innovations in microscopy have afforded a previously unseen view of viral infection occurring in real-time in living animals. Here, we review the contribution of intravital imaging to our understanding of cell-mediated immune responses to viral infections, with a particular focus on studies that visualize the antiviral effector cells responding to infection as well as virus-infected cells. We discuss methods to visualize viral infection in vivo using intravital microscopy (IVM) and significant findings arising through the application of IVM to viral infection. Collectively, these works underscore the importance of developing a comprehensive spatial understanding of the relationships between immune effectors and virus-infected cells and how this has enabled unique discoveries about virus/host interactions and antiviral effector cell biology.

Group 1 innate lymphoid-cell-derived interferon-γ maintains anti-viral vigilance in the mucosal epithelium

The oropharyngeal mucosa serves as a perpetual pathogen entry point and a critical site for viral replication and spread. Here, we demonstrate that type 1 innate lymphoid cells (ILC1s) were the major immune force providing early protection during acute oral mucosal viral infection. Using intravital microscopy, we show that ILC1s populated and patrolled the uninfected labial mucosa. ILC1s produced interferon-γ (IFN-γ) in the absence of infection, leading to the upregulation of key antiviral genes, which were downregulated in uninfected animals upon genetic ablation of ILC1s or antibody-based neutralization of IFN-γ. Thus, tonic IFN-γ production generates increased oral mucosal viral resistance even before infection. Our results demonstrate barrier-tissue protection through tissue surveillance in the absence of rearranged-antigen receptors and the induction of an antiviral state during homeostasis. This aspect of ILC1 biology raises the possibility that these cells do not share true functional redundancy with other tissue-resident lymphocytes.

Vaccinia viruses: vaccines against smallpox and vectors against infectious diseases and tumors

Less than 200 years after its introduction, widespread use of vaccinia virus (VACV) as a smallpox vaccine has eradicated variola virus. Along with the remarkable success of the vaccination program, frequent and sometimes severe adverse reactions to VACV were encountered. After eradication, VACV has been reserved for select populations who might be at significant risk for orthopoxvirus infections. Events over the past decade have renewed concerns over the potential use of variola virus as a biological weapon. Accordingly, interest in VACV and attenuated derivatives has increased, both as vaccines against smallpox and as vectors for other vaccines. This article will focus on new developments in the field of orthopoxvirus immunization and will highlight recent advances in the use of vaccinia viruses as vectors for infectious diseases and malignancies.

Bioterrorism and biologic warfare

Biologic agents have been used throughout history to influence battles. Recently, biologic agents have been used as terrorist weapons. A review of the history of biologic weapons and a medical overview of the Centers for Disease Control and Prevention Category A and B agents is provided, including history, pathogenesis, clinical presentation, microbiology/virology, diagnosis, treatment, and each agent's use or potential use as a weapon. Background information on public health issues surrounding bioterrorism and the role of oral and maxillofacial surgeons in a bioterrorist event also is provided.

Wanted, dead or alive: new viral vaccines

Vaccination is one of the most effective methods used for protecting the public against infectious disease. Vaccines can be segregated into two general categories: replicating vaccines (i.e., live, attenuated vaccines) and non-replicating vaccines (e.g., inactivated or subunit vaccines). It has been assumed that live attenuated vaccines are superior to non-replicating vaccines in terms of the quality of the antiviral immune response, the level of protective immunity, and the duration of protective immunity. Although this a prevalent viewpoint within the field, there are several exceptions to the rule. Here, we will explore the historical literature in which some of these conclusions have been based, including "Experiments of Nature" and describe examples of the efficacy of replicating vaccines compared to their non-replicating counterparts. By building a better understanding of how successful vaccines work, we hope to develop better "next-generation" vaccines as well as new vaccines against HIV--a pathogen of global importance for which no licensed vaccine currently exists.

Eczema herpeticum and clinical criteria for investigating smallpox

Eczema herpeticum can clinically resemble smallpox. On the basis of the algorithm for rapid evaluation of patients with an acute generalized vesiculopustular rash illness, our patient met criteria for high risk for smallpox. The Tzanck preparation was critical for rapid diagnosis of herpetic infection and exclusion of smallpox.

Infectious agents of bioterrorism: a review for emergency physicians

The terrorist attacks on the United States in 2001 and the anthrax release soon after brought the issue of bioterrorism to the forefront in the medical community. Bioterrorism is the use of a biologic weapon to create terror and panic. Biologic weapons, or bioweapons, can be bacteria, fungi, viruses, or biologic toxins. Because the emergency department represents the front line of defense for the recognition of agents of bioterrorism, it is essential that emergency physicians have the ability to quickly diagnose victims of bioterrorism. This review examines the most deadly and virulent category A agents of bioterrorism, that is, anthrax, smallpox, plague, botulism, hemorrhagic fever viruses, and tularemia. The focus is on epidemiology, transmission, clinical manifestations, diagnosis, and treatment.

5-(Dimethoxymethyl)-2'-deoxyuridine: a novel gem diether nucleoside with anti-orthopoxvirus activity

To provide potential new leads for the treatment of orthopoxvirus infections, the 5-position of the pyrimidine nucleosides have been modified with a gem diether moiety to yield the following new nucleosides: 5-(dimethoxymethyl)-2'-deoxyuridine (2b), 5-(diethoxymethyl)-2'-deoxyuridine (3b), 5-formyl-2'-deoxyuridine ethylene acetal (4b), and 5-formyl-2'-deoxyuridine propylene acetal (5b). These were evaluated in human foreskin fibroblast cells challenged with the vaccinia virus or cowpox virus. Of the four gem diether nucleosides, only the dimethyl gem diether congener showed significant antiviral activity against both viruses. This antiviral activity did not appear to be related to the decomposition to the 5-formyl-2'-deoxyuridine, which was itself devoid of anti-orthopoxvirus activity in these assays. Moreover, at the pH of the in vitro assays, 2b was very stable with a decomposition (to aldehyde) half-life of >15 d. The anti-orthopoxvirus activity of pyrimidine may be favored by the introduction of hydrophilic moieties to the 5-position side chain.

Neurobiological Weapons

Biological warfare is a potential threat on the battlefield and in daily life. It is vital for neurologists and other health care practitioners to be familiar with biological and toxic agents that target the nervous system. most illnesses caused by biological warfare agents are not commonly considered neurologic disease, however. Many of these agents (such as anthrax) may present with headache, meningitis, or mental status changes in addition to fever and other symptoms and signs (Tables 2 and 3). Thus, a neurologist may be consulted acutely to aid in diagnosis. Because of the incubation time of many biological agents and their protean manifestations, it is likely that health care workers will be on the front lines in the event of a bioterrorist attack. We must be prepared.

The Future of Smallpox Vaccination: is MVA the key?

Eradication of the smallpox virus through extensive global vaccination efforts has resulted in one of the most important breakthroughs in medical history, saving countless lives from the severe morbidity and mortality that is associated with this disease. Although smallpox is now extinct in nature, laboratory stocks of this virus still remain and the subject of smallpox vaccination has gained renewed attention due to the potential risk that smallpox may be used as a biological weapon by terrorists or rogue states. Despite having the longest history of any modern vaccine, there is still much to be learned about smallpox vaccination and the correlates of protection remain to be formally defined. This Commentary will discuss the strengths and weaknesses of traditional smallpox vaccination in comparison with immunization using modified vaccinia virus Ankura (MVA), a non-replicating virus with a strong safety record but weakened immunogenicity.