Immunogenicity of a highly attenuated MVA smallpox vaccine and protection against monkeypox

The potential use of smallpox as a biological weapon has led to the production and stockpiling of smallpox vaccine and the immunization of some healthcare workers. Another public health goal is the licensing of a safer vaccine that could benefit the millions of people advised not to take the current one because they or their contacts have increased susceptibility to severe vaccine side effects. As vaccines can no longer be tested for their ability to prevent smallpox, licensing will necessarily include comparative immunogenicity and protection studies in non-human primates. Here we compare the highly attenuated modified vaccinia virus Ankara (MVA) with the licensed Dryvax vaccine in a monkey model. After two doses of MVA or one dose of MVA followed by Dryvax, antibody binding and neutralizing titres and T-cell responses were equivalent or higher than those induced by Dryvax alone. After challenge with monkeypox virus, unimmunized animals developed more than 500 pustular skin lesions and became gravely ill or died, whereas vaccinated animals were healthy and asymptomatic, except for a small number of transient skin lesions in animals immunized only with MVA.     

Opsin expression: new mechanism for modulating colour vision

Each cone photoreceptor in the retina responds to light in a limited range of wavelengths, giving it a spectral phenotype. This phenotype is determined by the most prevalent of the photoreceptor's visual-pigment proteins (opsins) and is assumed to remain unchanged during an animal's lifetime. Here we show that in the Pacific pink salmon, Oncorhynchus gorbuscha, single cones can switch their spectral phenotype from ultraviolet to blue by regulating the production of the appropriate opsins as the fish grow older. This photoreceptor plasticity may operate to modulate colour vision as the salmon's lifestyle changes.     

Fire-induced erosion and millennial-scale climate change in northern ponderosa pine forests

Western US ponderosa pine forests have recently suffered extensive stand-replacing fires followed by hillslope erosion and sedimentation. These fires are usually attributed to increased stand density as a result of fire suppression, grazing and other land use, and are often considered uncharacteristic or unprecedented. Tree-ring records from the past 500 years indicate that before Euro-American settlement, frequent, low-severity fires maintained open stands. However, the pre-settlement period between about ad 1500 and ad 1900 was also generally colder than present, raising the possibility that rapid twentieth-century warming promoted recent catastrophic fires. Here we date fire-related sediment deposits in alluvial fans in central Idaho to reconstruct Holocene fire history in xeric ponderosa pine forests and examine links to climate. We find that colder periods experienced frequent low-severity fires, probably fuelled by increased understory growth. Warmer periods experienced severe droughts, stand-replacing fires and large debris-flow events that comprise a large component of long-term erosion and coincide with similar events in sub-alpine forests of Yellowstone National Park. Our results suggest that given the powerful influence of climate, restoration of processes typical of pre-settlement times may be difficult in a warmer future that promotes severe fires.     

Immigration, emigration and the ageing of the overseas-born population in the United Kingdom

This article uses data from the 1971 and 2001 Censuses, the 1999-2003 Labour Force Survey and the 1977 to 2002 International Passenger Survey to investigate the migration processes contributing to the age structure and ageing of the UK's overseas-born population. Overall almost half of recent decades' immigrants to the UK emigrate again within five years of arrival, but with large variation by overseas country of birth. Between half and two thirds of the immigrants born in the continental European Union, North America and Oceania emigrate again within five years, while 15 per cent of those born in the Indian subcontinent do so. Significant cumulative emigration more than five years after arrival is seen among earlier immigrants from the Indian subcontinent, the Caribbean Commonwealth and Europe. Large country-of-origin variations in the ratio of pension-age population to working-age population primarily reflect the country composition of immigration streams 30 or more years before.