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Viral Epidemiology and Control

A main focus of our current research is the transmission dynamics of respiratory syncytial virus, the major viral cause of infant and childhood severe pneumonia worldwide. RSV exhibits considerable genetic diversity (Groups A and B, and within each, a set of variants) which is apparently under immune selection. Occurrence of the virus is structured at the population level exhibiting sequential dominance of these variants; presumably resulting from (localized) strain specific herd immunity that provides competitive fitness to the least prevalent strains. The virus does not induce solid immunity, re-infection is the norm (though progressively less severe), and, as yet no vaccine appears to be on the horizon.
 
The fascination of RSV to the investigator is that despite its rather simple structure (there are only two proteins - F and G - on the surface recognized by the immune system); its ecology is complex and poorly understood. Paradoxes prevail: (i) while strain variation is the result of selective immune pressure, selection acts on only one surface protein (G) and occurs despite high degree of homology of the F protein even between Groups and against which neutralizing antibodies are raised; (ii) while recurrent epidemics clearly suggests (at least partial) immunity to re-infection, and epidemic structuring implies immunity to be variant specific, re-infection with the same strain can arise in two sequential epidemics and with different variants of the same Group within a single epidemic. (iii) While serum neutralizing antibody to both G and F protein exists, and appears to be a correlate of protection, the virus is rarely found systemically, and strain specific neutralizing activity of human convalescent sera has not been demonstrated. Most effort is being applied to develop live-attenuated vaccines to protect the most vulnerable age group which is children under 3 months of age - a time when the child is immunologically immature and where there is maximal presence of RSV specific maternal antibodies to interfere with the vaccine: unsurprisingly there are difficulties in balancing the needs of immunogenicity without reactogenicity.
 
The questions raised by the many unknowns of RSV epidemiology lend themselves to a multi-focused approach. We are engaged in community-based studies of the natural history of RSV infection and disease, including studies of household transmission, school re-infections, and contact patterns using conventional and electronic tagging location methods. This work is coupled to mathematical modeling studies of antigenically diverse pathogens and of RSV control programmes. Furthermore we are engaged in molecular and immuno-epidemiological studies to investigate the importance of strains variation to patterns of parasite persistence and development of immunity to re-infection. The work is set in framework of surveillance of severe paediatric pneumonia for multiple respiratory viruses within a well characterized study population.
This programme of research is headed by Prof James Nokes and is a  collaboration between Warwick (Graham Medley), the Health Protection Agency (Pat Cane) and the KEMRI-Wellcome Trust Research Programme in Kilifi.
 

First Symposium on Medical and Veterinary Virus Research Held in Nairobi

The 1st Medical and Veterinary Virus Research in Kenya (MVVR-K) symposium was held in Nairobi 8-9 September 2011. The two day symposium brought together over read more