title: Human metapneumovirus: enhanced pulmonary disease in cotton rats immunized with formalin-inactivated virus vaccine and challenged.
abstract: Cotton rats (Sigmodon hispidus) are susceptible to the recently discovered human metapneumovirus (hMPV), an agent closely related to human respiratory syncytial virus. Since certain respiratory syncytial virus vaccines can induce enhanced disease upon viral challenge, we have done similar experiments with hMPV in cotton rats. Young adult cotton rats were vaccinated with a formalin-inactivated preparation of hMPV strain C-85473, or with a mock preparation of the vaccine on day 0 and again on day 28. All animals were challenged intranasally on day 49 with 10(7) TCID50 of the same hMPV strain. Animals were sacrificed on days 4, 7, and 10 post-challenge and lungs were removed for viral quantitation, histopathology, and cytokine mRNA expression analysis (interferon-gamma (IFN-gamma) and interleukin-4 (IL-4)). Although the vaccinated animals showed almost complete protection from viral replication in the lungs (<10(2.0) TCID50 per gram), there was a dramatic increase in the lung pathology, particularly the interstitial pneumonitis and alveolitis with elevated serum neutralizing antibody titer prior to challenge. Cytokine profiles were distinctive from those observed during primary infection and re-infection. The data raise safety concerns for hMPV vaccine preparations.
authors.affiliation: Virion Systems, Inc., 9610 Medical Center Drive, Suite 100, Rockville, MD 20850, United States. kevinyim@virionsystems.com
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Yim
authors.forename: Rose P
authors.initials: RP
authors.lastname: Cragin
authors.forename: Marina S
authors.initials: MS
authors.lastname: Boukhvalova
authors.forename: Jorge C G
authors.initials: JC
authors.lastname: Blanco
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Hamlin
authors.forename: Guy
authors.initials: G
authors.lastname: Boivin
authors.forename: David D
authors.initials: DD
authors.lastname: Porter
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Prince
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism; D007114:Immunization; D007371:Interferon-gamma / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008171:Lung Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D029121:Metapneumovirus / Q000276:immunology*; D009500:Neutralization Tests; D018184:Paramyxoviridae Infections / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D051381:Rats; D016205:Sigmodontinae; D015164:Vaccines, Inactivated / Q000009:adverse effects; D014765:Viral Vaccines / Q000009:adverse effects* / Q000276:immunology*; D014779:Virus Replication
chemical_list: D016207:Cytokines; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; D015847:Interleukin-4; D007371:Interferon-gamma