Human Metapneumovirus and Respiratory Infections in South America

1. Human Metapneumovirus and Respiratory Infections in South America Gregory C. Gray, MD, MPH1; Sharon Setterquist MT(ASCP)1; Jose L. Sanchez, MD, MPH2;Teresa C. T. Peret, PhD3; Guy Boivin, MD4; Linda C. Canas5; James S. Neville, MD, MPH5;Gloria Chauca6; James G. Olson, PhD6 1Center for Emerging Infectious Diseases, Department of Epidemiology, University of Iowa College of Public Health, Iowa City, IA; 2US Military HIV Research Program, Rockville, MD; 3Respiratory Virus Section, Centers for Disease Control and Prevention, Atlanta, GA; 4Centre Hospitalier Universitaire de Quebec, Quebec City, Canada; 5Air Force Institute for Operational Health, Brooks AFB, TX; 6Naval Medical Research Center Detachment, Lima, Peru Gregory C. Gray, MD, MPH Center for Emerging Infectious Diseases Univ. of Iowa College of Public Health 200 Hawkins Dr., C21K GH Iowa City, IA 52245 Tel (319) 384-5008 Fax (319) 384-5004 www.public-health.uiowa.edu/CEID Results Five of the RT-PCR+ specimens yielded hMPV growth in LLC-MK2 cell culture. Growth was confirmed by detecting hMPV by RT-PCR in the cell culture supernatants. Cell culture supernates were aliquotted for RT-PCR every 5 days for a total of 25 days prior to new media replacement. Scanning electron microscopy demonstrated virus like particles emerging from LLC-MK2 cells (Fig. 2). Abstract Background: Relatively little is known regarding the epidemiology of the newly described respiratory pathogen, human metapneumovirus (hMPV). Few studies of this pathogen have been published regarding its prevalence in South America. Methods: We sought to evaluate the prevalence of hMPV among 397 archived viral culture specimens collected during the period 1/8/2002 to 9/17/2003 from patients (ages 2 months to 89 years) with influenza-like illness from 6 sites in Peru (85% of samples), 1 site each in Argentina, Ecuador, and Colombia. All patients’ cultures had been negative for influenza A & B, adenovirus, RSV, and parainfluenza 1, 2, and 3. The specimens were screened with previously published F gene primers in a one-step RT-PCR. Specimens with positive or nonspecific bands were further evaluated using 2-step N-gene and multiple F-gene primer set procedures. Results: Eleven (2.8%) of the 397 specimens were positive by both F and N-gene procedures. Ten (90.9%) of these positive hMPV specimens were obtained from Peruvian patients aged 9 months to 9 years and one from a 38 year old. Positive specimens were collected in the months of April thru October. Five (45.5%) of these specimens yielded isolates after culture on LLC-MK2 cells. Conclusions: Although these data are preliminary, they suggest that hMPV is endemic in Peru and likely in other countries in South America. Among patients with flu-like illness, hMPV seems most prevalent among children. Introduction In June 2001, Osterhaus1 and colleagues reported a newly recognized human respiratory virus (Pneumovirinae subfamily, Paramyxoviridae family) termed the human Metapneumovirus (hMPV). Illnesses associated with hMPV infections are similar to those seen with RSV, with some patients suffering severe respiratory disease. One published study has found 70% of infants (n=30) with severe RSV bronchiolitis to be coinfected with hMPV2 and another study found 20% of respiratory specimens screened negative for other respiratory viruses (n=248) to have evidence for hMPV infection.3 hMPV infections have been found to occur in patients of all ages and account for a significant portion of respiratory infections.1-4 Methods Influenza-like illness specimens collected under the Department of Defense’s Global Emerging Infectious System were used in this study. Viral culture specimens were collected from 6 sites in Peru and 1 site each in Argentina, Ecuador, and Colombia. Specimens were preserved at -800C and shipped to the Naval Medical Research Center Detachment, in Lima, Peru. Specimens were later shipped in batch to the Air Methods (continued) Force Institute for Operational Health, Brooks City-Base, TX where they were evaluated with routine respiratory virus culture. After culture work was completed, the specimens were shipped to the Center for Emerging Infectious Diseases at the University of Iowa. At the University of Iowa the specimens were screened with previously published F gene primers4 in a one-step RT-PCR (Fig. 1). Specimens with positive or nonspecific bands were further evaluated using 2-step N-gene5 and multiple F-gene primer set6 procedures. Fig. 1: RT-PCR screening for 347BP product Results 11 (2.8%) of the 397 specimens were positive by both F and N-gene procedures ( Fig. 1 and Table 1). hMPV was detected among patients ranging in age from 9 months to 38 years. RT-PCR Positive specimens were collected in the months of April through October. Conclusions These data suggest that hMPV is endemic in Peru and likely in South America. The isolates are likely the first hMPV isolates from South America. Among patients with flu-like illness, hMPV seems most commonly found among children. Due to the complexities of specimen shipment and processing, our prevalence calculations likely underestimate the true prevalence of hMPV in Peru. References 1. Nat Med 2001;7:719-24. 4. J Infect Dis 2003;187:785-790 2. Emerg Infect Dis 2003;9:372-374. 5. J Clin Micro 2003;41:100-105 3. N Engl J Med. 2004;350:443-50 6. J Infect Dis 2002;185 :1660-3 Panel C Panel A Panel B Fig. 2: Scanning electron microscopy images of viral-like particles emerging from LLC-MK2 cells. Resolution: Panel A 30k; Panel B 35k; Panel C 100k