NEW YORK (Reuters Health) - Sequencing the phosphoprotein gene of the human metapneumovirus (hMPV) makes it possible to reliably classify the newly discovered pathogen into two main lineages and four sublineages, Australian researchers report.
While it is not yet clear which types or subtypes cause more severe illness, Dr. Ian M. Mackay of the Royal Children’s Hospital & University of Queensland and colleagues note, the findings will make it possible to begin to answer that question and also contribute to the development of vaccination against and treatment for hMPV infection.
Illness caused by hMPV, first described in 2001, is “clinically indistinguishable” from illness resulting from human respiratory syncytial virus, but hMPV is not genetically similar to hRSV, but more closely related to avian pneumovirus, Dr. Mackay and colleagues note in the December 1st issue of The Journal of Infectious Disease.
To begin to characterize the virus, the researchers screened about 5000 specimens collected from patients who visited hospitals for suspected acute respiratory infection between 2001 and 2003. The prevalence of the virus in screened patients was 8.1%, 4.0% and 3.8% for 2001, 2002 and 2003, respectively.
The researchers sequenced nucleoprotein and phosphoprotein genes from a randomly selected group of the hMPV-positive samples.
Based on variation in the P gene, Dr. Mackay and colleagues found two main lineages, and two subtypes within each lineage, and called the types A1, A2, B1 and B2.
“The sequence of the P gene we have used to design our primers is well conserved across all characterized strains of hMPV, while spanning a region that contains significant variability among the strains,” Dr. Mackay told Reuters Health.
“The conserved regions permit easy amplification whilst the variable region provides reliable phylogenetic information on the strains,” he continued. “The nucleoprotein gene, while producing a protein that is considered well conserved among the virus family, contains significant sequence variation among different viral lineages.”
Dr. Mackay said his team is now investigating whether the viral subtypes cause different degrees of disease severity, studying the over 500 hMPV strains they have identified since 2001.
“Improved diagnostic techniques are now available to detect this pathogen. However many ‘in-house’ assays published in the literature appear to bias detection towards A-type strains, probably reflecting that the earliest sequences available for assay design were of type A,” Dr. Mackay said. “It is important that diagnostic laboratories, and researchers performing epidemiological studies apply an assay capable of detecting all known viral lineages.”
Source: J Infect Dis 2004;190:1913-1918. [ Google search on this article ]
MeSH Headings:Classification: Information Science: RNA Virus Infections: Paramyxoviridae Infections: Pneumovirus Infections: Mononegavirales Infections: Information ScienceCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
