Treatment of variola major with adenine arabinoside

Comparative pathology of smallpox and monkeypox in man and macaques

In the three decades since the eradication of smallpox and cessation of routine vaccination, the collective memory of the devastating epidemics caused by this orthopoxvirus has waned, and the human population has become increasingly susceptible to a disease that remains high on the list of possible bioterrorism agents. Research using surrogate orthopoxviruses in their natural hosts, as well as limited variola virus research in animal models, continues worldwide; however, interpretation of findings is often limited by our relative lack of knowledge about the naturally occurring disease. For modern comparative pathologists, many of whom have no first-hand knowledge of naturally occurring smallpox, this work provides a contemporary review of this historical disease, as well as discussion of how it compares with human monkeypox and the corresponding diseases in macaques.

Countermeasures and vaccination against terrorism using smallpox: pre-event and post-event smallpox vaccination and its contraindications

Smallpox, when used as a biological weapon, presents a serious threat to civilian populations. Core components of the public health management of a terrorism attack using smallpox are: vaccination (ring vaccination and mass vaccination), adverse event monitoring, confirmed and suspected smallpox case management, contact management, identifying, tracing, monitoring contacts, and quarantine. Above all, pre-event and post-event vaccination is an indispensable part of the strategies. Since smallpox patients are most infectious from onset of the rash through the first 7-10 days of the rash, vaccination should be administered promptly within a limited time frame. However, vaccination can accompany complications, such as postvaccinial encephalitis, progressive vaccinia, eczema vaccinatum, and generalized vaccinia. Therefore, vaccination is not recommended for certain groups. Public health professionals, as well as physicians and government officials, should also be well equipped with all information necessary for appropriate and effective smallpox management in the face of such a bioterrorism attack.

A survey of antiviral drugs for bioweapons

Smallpox (variola major), and the haemorrhagic fever viruses (filoviruses and arenaviruses) are classified as Category A biowarfare agents by the Centers for Disease Control. Category A agents pose a significant risk to public health and national security because they can be easily disseminated by aerosol, although with the exception of variola, they are not easily transmitted from person to person. An attack with these viruses would result in high morbidity and mortality and cause widespread panic. With the exception of smallpox and Argentine haemorrhagic fever virus, there are no vaccines or approved treatments to protect against these diseases. In this review we focus on promising prophylactic, therapeutic and disease modulating drugs (see Figure 1 for select chemical structures).

A review of compounds exhibiting anti-orthopoxvirus activity in animal models

Several animal models using mice (most frequently), rabbits, or monkeys have been used to identify compounds active against orthopoxvirus infections. The treatment of vaccinia virus infections has been well studied in models involving infection of scarified skin or eyes, or resulting from intravenous, intraperitoneal, intracerebral, or intranasal virus inoculation. Cowpox virus has been used in intranasal or aerosol infection studies to evaluate the treatment of lethal respiratory infections. Rabbitpox, monkeypox, and variola viruses have been employed to a lesser extent than the other viruses in chemotherapy experiments. A review of the literature over the past 50 years has identified a number of compounds effective in treating one or more of these infections, which include thiosemicarbazones, nucleoside and nucleotide analogs, interferon, interferon inducers, and other unrelated compounds. Substances that appear to have the greatest potential as anti-orthopoxvirus agents are the acyclic nucleotides, (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (cidofovir, HPMPC) and 1-[((S)-2-hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl]cytosine (cyclic HPMPC), and the acyclic nucleoside analog, 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S2242). Other classes of compounds that have not been sufficiently studied in lethal infection models and deserve further consideration are thiosemicarbazones related to methisazone, and analogs of adenosine-N(1)-oxide and 1-(benzyloxy)adenosine.

The smallpox story: life and death of an old disease

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Antiviral treatment of chronic hepatitis B virus infection: pharmacokinetics and side effects of interferon and adenine arabinoside alone and in combination

In an uncontrolled trial, 29 patients with chronic hepatitis B virus infection were treated with 93 courses of adenine arabinoside at doses ranging from 2.5 to 15 mg/kg per day. Most patients were treated concomitantly with human leukocyte interferon. Significant, but transient, neurotoxicity was seen with adenine arabinoside therapy in 44% of all courses. Manifestations of toxicity were mainly neurological and ranged from pain syndromes to tremors and, rarely, seizures. Suppression of numbers of lymphocytes was also noted. All effects were reversible with time. The extent of toxicity was dependent upon the dosage of adenine arabinoside. Treatment with interferon appeared to potentiate the occurrence of toxicity with adenine arabinoside. Arabinofuranosylhypoxanthine serum levels increased in a dose-dependent manner and tended to accumulate in interferon-treated hepatitis patients during a course of therapy. Elevated blood levels and drug accumulation were associated with toxicity in a significant fashion. Human leukocyte interferon was administered to 38 patients in 113 separate courses. Interferon side effects were rapidly reversible upon cessation of therapy. These included initial fever, myalgias, and hair loss as well as suppression of granulocytes, platelets, and lymphocytes in the blood.