Animal vaccine shows potential for the development of human SARS immunisation

The current issue of the LANCET provides evidence for the effectiveness of experimental SARS immunisation in animal studies. The preliminary results show the potential for the development of human SARS immunisation.

Alexander Bukreyev from the US National Institutes of Health and colleagues immunised 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 1 month after immunisation. 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 5 and 8 days after infection with the SARS coronavirus.

In a research letter (p 2139), Jan ter Meulen from Crucell Holland, Leiden, Netherlands, and colleagues investigated the prevention of SARS coronavirus infection with a neutralising 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 (p 2102), 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."

Severe Acute Respiratory Syndrome (SARS) is an atypical form of pneumonia that first appeared in November 2002 in Guangdong Province, China.

After the People's Republic of China suppressed all news of the outbreak both internally and abroad, it spread rapidly, reaching neighboring Hong Kong and Vietnam in late February 2003, and then to other countries via international travel of infected persons. The last case in this outbreak occurred in June, 2003. In the outbreak, SARS caused 8,069 cases of disease and 775 deaths.