Human Metapneumovirus Reinfection in Kamphaeng Phet Province, Thailand, Determined by ELISA Using Purified Soluble Fusion Protein*

Session I – Pavlin, Julie – Abstract 1 of 2

Title of Contribution:  Human Metapneumovirus Reinfection in Kamphaeng Phet Province, Thailand, Determined by ELISA Using Purified Soluble Fusion Protein*

Authors: J. A. Pavlin1, A. C. Hickey2, N. Ulbrandt3, Y-P. Chan2, T. P. Endy4, M.S. Boukhvalova5, S. Chunsuttiwat6, A. Nisalak1, D. H. Libraty7, S. Green7, A. L. Rothman7, F. A. Ennis7, R. Jarman1, R. V. Gibbons1, C. C. Broder2

Affiliations: 1Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand; 2Uniformed Services University, Bethesda, MD, USA; 3MedImmune, Inc., Gaithersburg, MD, USA; 4SUNY Upstate Medical University, Syracuse, NY, USA; 5Virion Systems, Inc., Rockville, MD, USA; 6Ministry of Public Health, Bangkok, Thailand; 7University of Massachusetts Medical School, Worcester, MA, USA.

Abstract: Human metapneumovirus (hMPV) is a newly discovered paramyxovirus that causes acute respiratory illness. Despite apparent near-universal exposure during early childhood, immunity is transient.  An indirect screening ELISA using a recombinant, soluble, fusion (F) glycoprotein derived from hMPV was used to test for anti-F IgG in 1380 randomly selected acute and convalescent sera collected from school age children (6-17 years) who had an acute febrile illness in Kamphaeng Phet, Thailand, between 1998 and 2002. The majority of illnesses included respiratory symptoms but had no known etiology.  Of the serum sample pairs tested, 1376 (99.7%) showed evidence of prior infection with hMPV. Sixty-six paired specimens demonstrated a four-fold or greater rise in anti-hMPV titer, for an overall re-infection rate of 4.9%. Two children demonstrated evidence of an initial infection. Forty-eight of the 68 new or re-infections occurred in 2000, accounting for 13.2% of all nonflaviviral febrile illnesses in the study population in that year.  32 of these cases occurred in a discrete 2 week time period.  Of 68 positive cases, 89.9% reported one or more respiratory symptoms compared to 69.2% of tested negative cases (p<.001). All positive samples were also tested for an increase in titer to respiratory syncytial virus F protein and 27% exhibited a four-fold or greater rise in titer; however the increase was less than that seen for hMPV F. These results demonstrate that hMPV reinfections cause illness at a rate equal to that seen for initial infections.  hMPV may represent a more significant impact in older children than previously realized and may be the cause of significant outbreaks.

*This research was presented in part at the American Society of Tropical Medicine and Hygiene annual meeting, Atlanta, 12-16 Nov 2006 and at the Infectious Diseases Society of America annual meeting, San Diego, 4-7 October 2007 (abstract 718).  It has also been published in the Journal of Infectious Diseases 2008;198:836-42.