On 10/13/16,  John V. Williams, MD, spoke at our ID grand rounds.  He is the chief of Pediatric Infectious Diseases at Children’s Hospital of Pittsburgh.  His presentation focused on Human Metapneumovirus, (hMPV) which is a paramyxovirus and a common respiratory pathogen. A few highlights from the presentation.

• In children <5, hMPV was the second most common isolated respiratory virus after RSV, and slightly more common than influenza.
• Serologic evidence of infection is near universal by age 5, but adults are susceptible to infections as well.
• Peak season for hMV classically follows RSV and influenza, but there is large overlap between the 3 viruses
• There are four main subtypes of hMPV, and while the virus has a high mutation rate, there is not the significant drift/shift that is commonly seen with influenza
• In children wheezing is a common manifesting, but most infections are self-limited, there is very little mortality in children in developed countries from hMPV
• There are data that hMPV can cause outbreaks in nursing facilities and be associated with significant morbidity/mortality, similar to influenza
• Broadly neutralizing antibodies again the F antigen can prevent infection if used for prophylaxis (similarly to palivizumab for RSV) and also to treat infections in a mammalian model
• Some neutralizing antibodies have shows efficacy vs both hMPV and RSV, suggesting possible vaccine target in the future
• Immunological response involving CD8+ T-Cells is complex in pulmonary viral infections, and signalling from PD-1 System and other immune regulation systems are involved in the up-regulation and down-regulation of inflammation with hMPV infection

Overall this was an excellent presentation about epidemiology, immunology and possible future vaccines/therapeutics for this infection.

Selected Pubmed References for further reading.

Bates et al, Immunogenicity and efficacy of alphavirus-derived replicon vaccines for respiratory syncytial virus and human metapneumovirus in nonhuman primates Vaccine 2016

Wen et al  Lung CD8+ T Cell Impairment Occurs during Human Metapneumovirus Infection despite Virus-Like Particle Induction of Functional CD8+ T Cells. Journal of Virology 2015

Schuster et al. A broadly neutralizing human monoclonal antibody exhibits in vivo efficacy against both human metapneumovirus and respiratory syncytial virus. Journal of Infectious Diseases 2015

Erickson et al. Viral acute lower respiratory infections impair CD8+ T cells through PD-1. Journal of Clinical Investigation 2012

Williams et al. Population-based incidence of human metapneumovirus infection among hospitalized children. Journal of Infectious Diseases 2010