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Research published in a recent issue of The Lancet provide evidence for the effectiveness of experimental SARS immunization in animal studies. Although further research is required, these preliminary results show the potential for the development of human SARS immunization.
Alexander Bukreyev from the U.S. National Institutes of Health and colleagues immunized eight African green monkeys, four with a single dose of an intranasal vaccine derived from an experimental paediatric parainfluenza vaccine (engineered to express a major protective antigen of the SARS coronavirus), the other four with a control. All monkeys were deliberately infected with SARS coronavirus one month after immunization. The monkeys given the SARS vaccine had antibodies to the SARS coronavirus in their blood indicating an immune response to vaccination; none of these monkeys had evidence of viral shedding (presence of the virus in samples from the respiratory tract). By contrast, all four monkeys in the control group had evidence of viral shedding between five and eight days after infection with the SARS coronavirus.
In a research letter, Jan ter Meulen from Crucell Holland, Leiden, Netherlands, and colleagues investigated the prevention of SARS coronavirus infection with a neutralizing human monoclonal antibody in ferrets (an animal species that can be readily infected with the SARS coronavirus). Prophylactic administration of the monoclonal antibody at 10 mg per kg bodyweight substantially reduced replication of the SARS coronavirus in the lungs of infected ferrets, completely prevented the development of SARS coronavirus-induced lung damage, and prevented viral shedding in pharyngeal secretions. The investigators comment: 'The data generated in this animal model show that administration of a human monoclonal antibody might offer a feasible and effective prophylaxis for the control of human SARS coronavirus infection.
In an accompanying commentary, Ruth Foxwell from the University of Canberra, Australia, concludes, "Bukreyev, ter Meulen, and their colleagues have shown that SARS can be effectively prevented by immunisation of the mucosa of the respiratory tract and immunoprophylaxis in animal models. Whilst further studies are required before these concepts can be applied to human beings, the findings provide exciting strategies for the prevention of disease in target communities and treatment of at-risk individuals."
Source: The Lancet