Vaccinia necrosum: a forgotten disease

Intravenous and isolated limb perfusion delivery of wild type and a tumor-selective replicating mutant vaccinia virus in nonhuman primates

In this study we examine the safety, feasibility, and biodistribution of a tumor-selective mutant vaccinia (vvDD) and wild-type WR (vF13) vaccinia after delivery via intradermal or intravenous infection or isolated limb perfusion (ILP) in rhesus macaques. By intradermal inoculation, 10(6) PFU of vvDD caused a minimal skin reaction whereas vF13 caused marked erythema and necrosis with a peak indurated area of 108 cm2. By intravenous delivery, vvDD caused no clinical symptoms of viremia and no viral recovery from tissues, serum, saliva, urine, or feces. In contrast, vF13 caused symptoms of lethargy, anorexia, fever, and signs of viremia. Delivery of vF13 via ILP resulted in numerous cutaneous pox lesions localized solely to the perfused limb with high viral recovery in the perfused skin and muscle. ILP with vvDD resulted in no visible pox lesions and no clinical signs or symptoms of viremia. No long-term toxicity was identified after ILP with 10(9) PFU of vvDD, and no virus was recovered from any tissue, serum, saliva, urine, or fecal sample. These results suggest that vvDD appears to be safe in primates, and thus vvDD should be further investigated for clinical trial in human cancer patients.

Smallpox: what the dermatologist should know

Despite the eradication of naturally occurring smallpox in 1977, stores of the virus have been maintained in laboratories in the United States and Russia. It is feared that certain rogue states and terrorist organizations may have illicitly acquired the virus with the intent of unleashing it as an agent of bioterrorism. The United States and other nations have begun vaccinating individuals in the military and health care workers who might become exposed. Primary care providers and dermatologists will be called upon to evaluate potential index cases and vaccination reactions. In this report, the authors review the essential clinical aspects of smallpox and potential reactions to smallpox vaccination. Special attention is given to eczema vaccinatum, which can occur in vaccinees and their family contacts with active or quiescent atopic dermatitis or a personal history of eczema.

Pathogenesis and potential antiviral therapy of complications of smallpox vaccination

Vaccination against smallpox may result in a variety of complications, ranging in severity from benign to lethal. Universal vaccination was halted in the US in 1972, so almost half the present population has never been vaccinated. Because side effects occur most often in first-time vaccinees, current plans for rapid large-scale vaccination in the event of bioterrorist attack raise concerns about the occurrence of a large number of adverse events. Most complications result from the excessive replication of vaccinia virus, making them potential targets for antiviral therapy. Effective treatment is especially needed for persons with atopic dermatitis or eczema, who are unusually susceptible to the initiation and spread of vaccinia infection because of defects of innate immunity in the skin, and for individuals with defective cell-mediated immunity, who are unable to eliminate vaccinia infection once it has begun. In the past, many complications were treated with vaccinia immune globulin (VIG) and/or the antiviral drug methisazone, but neither was tested in placebo-controlled trials. New antiviral drugs are now available, but have not yet been evaluated for treating vaccinia infections in humans. Both laboratory research and clinical studies are needed to help prevent serious complications in any major vaccination campaign.

Progressive vaccinia

The resumption of smallpox vaccination for health care workers and other first responders has raised concern about the occurrence of complications in people with immunodeficiency disorders, including those infected with human immunodeficiency virus. During the era of universal vaccination, roughly 1 person per million vaccinees in the general population developed progressive vaccinia, which is characterized by the relentless outward spread of infection from the vaccination site and eventual dissemination to other areas on the body. Review of 56 cases reported in the English-language medical literature from 1893 through 1997 indicates that the condition occurred only in persons with severe cell-mediated immunodeficiency. Progressive vaccinia was found to be lethal in infants who completely lacked cellular immune function, but infection resolved in many adults with acquired immunodeficiency. Almost all cases were treated with vaccinia immune globulin, but its efficacy has never been tested in a placebo-controlled trial. Further research is needed to develop effective forms of therapy.