Lethal synergism between influenza virus and Streptococcus pneumoniae: characterization of a mouse model and the role of platelet-activating factor receptor.
A lethal synergism exists between influenza virus and pneumococcus, which likely accounts for excess mortality from secondary bacterial pneumonia during influenza epidemics. Characterization of a mouse model of synergy revealed that influenza infection preceding pneumococcal challenge primed for pneumonia and led to 100% mortality. This effect was specific for viral infection preceding bacterial infection, because reversal of the order of administration led to protection from influenza and improved survival. The hypothesis that influenza up-regulates the platelet-activating factor receptor (PAFr) and thereby potentiates pneumococcal adherence and invasion in the lung was examined in the model. Groups of mice receiving CV-6209, a competitive antagonist of PAFr, had survival rates similar to those of control mice, and lung and blood bacterial titers increased during PAFr inhibition. These data suggest that PAFr-independent pathways are operative in the model, prompting further study of receptor interactions during pneumonia and bacteremia. The model of lethal synergism will be a useful tool for exploring this and other mechanisms underlying viral-bacterial interactions.
Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105-2794, USA. jon.mccullers@stjude.org
Jonathan A
JA
McCullers
Jerold E
JE
Rehg
D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008168:Lung / Q000382:microbiology / Q000473:pathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D009975:Orthomyxoviridae / Q000378:metabolism / Q000472:pathogenicity*; D009976:Orthomyxoviridae Infections / Q000150:complications* / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D011018:Pneumonia, Pneumococcal / Q000150:complications* / Q000378:metabolism; D011726:Pyridinium Compounds / Q000494:pharmacology; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D013296:Streptococcus pneumoniae / Q000378:metabolism / Q000472:pathogenicity*
D010980:Platelet Membrane Glycoproteins; D011726:Pyridinium Compounds; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; C053321:CV 6209