Experimental infection of human volunteers with the U-virus—A strain of ECHO virus Type 11

Abstract

Re-examination of the U-virus of Philipson & Wesslén has shown it to be a typical ECHO virus closely related to Type 11 of this group. Ultrafiltration and ultra-centrifugation techniques indicate that the virus particle has a diameter of about 27 mν and serological studies confirm its antigenic relationship to the ECHO group.The virus has been successfully transmitted via the nasal route to volunteer adult subjects. All of them became infected but the clinical picture showed no more than a very mild gastro-intestinal illness or a slight disturbance of the general well-being.Passage in monkey kidney cells appeared to attenuate significantly when compared with short-term passage in human embryo-lung culture, and this seemed to affect the isolation rate from subjects so infected.The virus is highly immunogenic. Antibodies to the U-virus have been found in normal persons residing in Great Britain.We wish to thank the volunteers for their willing co-operation and Miss J. B. Macdonald for help with the clinical observations. Dr A. D. Macrae supplied the ECHO Type 11 prototype virus and immune serum and Prof. C. H. Stuart-Harris supplied the pooled human sera. The Director, Microbiological Research Establishment, Porton, afforded the use of the ultracentrifuge. Monkey kidneys were supplied by the M.R.C. polio vaccine control laboratories. Mr M. C. Brebner and Miss P. K. Pearce assisted with the laboratory work.