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ate: Mon 8 Aug 2005 From: George Robertson Source: Reuters Health, Mon 8 Aug 2005 [edited] _____________________________________________________________ Monkeypox Outbreak Shows Smallpox Vaccine Works ----------------------------------------------- A 2003 outbreak of monkeypox in the United States has helped prove that smallpox vaccinations can protect for decades, U.S. researchers said on Monday [8 Aug 2005]. The study could help officials trying to come up with a plan for mass-vaccination against the often deadly smallpox virus and its relatives, should such a virus ever be used in a biological attack. _____________________________________________________________ The researchers found 3 people who were evidently infected by the monkeypox virus, spread mostly by pet prairie dogs in the Midwest, who never had any symptoms. The 3 had last been vaccinated against smallpox before the jabs were discontinued. One was vaccinated 13 years ago, another 29 years ago and the third 48 years ago. "These individuals were unaware that they had been infected, because they were spared any recognizable disease symptoms," Mark Kenneth Slifka, of Oregon Health & Sciences University, and colleagues wrote in their report, published in the journal Nature Medicine [see below]. _____________________________________________________________ "Together, this shows that the U.S. monkeypox outbreak was larger than previously realized and, more importantly, shows that cross-protective antiviral immunity against West African monkeypox can potentially be maintained for decades after smallpox vaccination." _____________________________________________________________ Smallpox was eradicated in 1979 after a global vaccination program. But experts fear the virus or a related virus could be used as a biological weapon. About half the U.S. adult population has been vaccinated as part of routine efforts that stopped in 1972 for civilians and 1990 for the military. Studies have shown that immunity lasts as long as 75 years. _____________________________________________________________ Now work is underway to stockpile doses of vaccine in case of an attack, while tests are also underway to see whether perhaps some people might be protected by their old vaccinations. But no one has been able to do a real test of how well the vaccine protects, until the monkeypox outbreak, traced to pet rodents imported from West Africa, where the close relative of smallpox is well entrenched and still common. _____________________________________________________________ The team tested 44 people from Wisconsin, the epicenter of the outbreak, which originated at a pet store in Illinois. At least 39 people were reported infected with monkeypox in Wisconsin, they said. "We screened subjects and included in the study only those who had close contact with monkeypox-infected individuals or monkeypox-infected prairie dogs," they wrote. They found 3 people who had clear evidence of infection in their blood, yet never showed any symptoms of monkeypox. All had been previously vaccinated against smallpox. _____________________________________________________________ They also found that the monkeypox viruses spread even without direct contact, something to be aware of should there ever be a smallpox attack. "A common misconception of the U.S. monkeypox outbreak is that infection requires direct contact or direct inoculation through scratches or bites in order for infected prairie dogs to transmit monkeypox to humans," the researchers wrote. But the virus apparently can be carried in the air and by tiny sneezed droplets. "In one case, a subject contracted monkeypox after an infected prairie dog was carried into her home when she was not present. The prairie dog was apparently not placed on the floor or furniture, and yet this subject, who had no contact with prairie dogs or other individuals with monkeypox, contracted the disease," they wrote. _____________________________________________________________ -- George A. Robertson, PhD Vice President, Research and Development DOR Biopharma Suite 435, 1691 Michigan Ave. Miami, FL 33139, USA [The report in Nature Medicine referred to above was published online on Sun 7 Aug 2005: . _____________________________________________________________ The report is entitled "Multiple diagnostic techniques identify previously vaccinated individuals with protective immunity against monkeypox" by Erika Hammarlund and 9 others at the Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon 97006, USA. The Abstract states that "Approximately 50 percent of the US population received smallpox vaccinations before routine immunization ceased in 1972 for civilians and in 1990 for military personnel. Several studies have shown long-term immunity after smallpox vaccination, but skepticism remains as to whether this will translate into full protection against the onset of orthopoxvirus-induced disease. The US monkeypox outbreak of 2003 provided the opportunity to examine this issue. Using independent and internally validated diagnostic approaches with 95 percent sensitivity and 90 percent specificity for detecting clinical monkeypox infection, we identified 3 previously unreported cases of monkeypox in preimmune individuals at 13, 29 and 48 years after smallpox vaccination. These individuals were unaware that they had been infected because they were spared any recognizable disease symptoms. Together, this shows that the US monkeypox outbreak was larger than previously realized and, more importantly, shows that cross-protective antiviral immunity against West African monkeypox can potentially be maintained for decades after smallpox vaccination." _____________________________________________________________ In similar vein, Yvette Edghill-Smith et al., in an article published in Nature Medicine on 1 Jul 2005 (Nature Medicine 11, 740-747), concluded from experiments using a Rhesus macaque model of infection with monkeypox virus that: "Smallpox vaccine-induced antibodies are necessary and sufficient for protection against monkeypox virus." _____________________________________________________________ These findings are not unexpected in that vaccinia virus (i.e. smallpox vaccine) and 21 other orthopoxviruses share the same inventory of 90 essential genes for infection and multiplication in cells, see: Upton, C., Slack, S., Hunter, A. L., Ehlers, A. & Roper, R. L. Poxvirus orthologous clusters: towards defining the minimum essential poxvirus genome. Journal of Virology, 77, 7590 - 7600, (2003). - Mod.CP] _____________________________________________________________ [see also: Monkeypox virus, virulence differences - USA (Midw... 20050717.2055 2003 ---- Monkeypox, human, prairie dogs - USA (06) 20030612.1450 Monkeypox, human, prairie dogs - USA (07): transmi... 20030613.1458 Monkeypox, human, prairie dogs - USA (08): NJ NOT 20030614.1470 Monkeypox, human, prairie dogs - USA (09) 20030615.1479 Monkeypox, human, prairie dogs - USA (10): Kentucky 20030617.1498 Monkeypox, human, prairie dogs - USA (11) 20030618.1504 Monkeypox, human, prairie dogs - USA (12) 20030619.1510 Monkeypox, human, prairie dogs - USA (13) 20030626.1577 Monkeypox, human, prairie dogs - USA (14) 20030702.1634 Monkeypox, human, prairie dogs - USA (15) 20030710.1692 Monkeypox, human, prairie dogs - USA (WI, IL, IN) 20030608.1412 Monkeypox, human, prairie dogs - USA(WI,IL,IN)(02) 20030609.1422 Monkeypox, human, prairie dogs - USA(WI,IL,IN)(03) 20030610.1433 Monkeypox, human, prairie dogs - USA(WI,IL,IN)(04) 20030611.1436 Monkeypox, human, prairie dogs - USA(WI,IL,IN)(05) 20030611.1442 Monkeypox, human - Congo Rep (02): confirmed 20030626.1573 Monkeypox, human - Congo Rep (03) 20030710.1687 Monkeypox, human - Congo Rep: suspected 20030623.1545 Monkeypox - European Union: prevention (import ban) 20030617.1497 Monkeypox - USA: recommendations for vets 20030613.1457 2002 ---- Monkeypox - Congo DR (Equateur) 20020228.3654 Monkeypox - Congo DR (Equateur) (02) 20020314.3744 Monkeypox - Congo DR (Equateur) (03) 20020315.3749 Monkeypox - Congo DR (Equateur) (04) 20020322.3797 Monkeypox - Congo DR (Equateur) (05) 20020409.3918 Monkeypox - Congo DR (Equateur) (06) 20020410.3926 Monkeypox - Congo DR (Equateur) (07) 20021025.5638 Monkeypox virus, genome 20020627.4619] .......................cp/msp/lm