The two major human metapneumovirus genetic lineages are highly related antigenically, and the fusion (F) protein is a major contributor to this antigenic relatedness.
The growth properties and antigenic relatedness of the CAN98-75 (CAN75) and the CAN97-83 (CAN83) human metapneumovirus (HMPV) strains, which represent the two distinct HMPV genetic lineages and exhibit 5 and 63% amino acid divergence in the fusion (F) and attachment (G) proteins, respectively, were investigated in vitro and in rodents and nonhuman primates. Both strains replicated to high titers (> or =6.0 log(10)) in the upper respiratory tract of hamsters and to moderate titers (> or =3.6 log(10)) in the lower respiratory tract. The two lineages exhibited 48% antigenic relatedness based on reciprocal cross-neutralization assay with postinfection hamster sera, and infection with each strain provided a high level of resistance to reinfection with the homologous or heterologous strain. Hamsters immunized with a recombinant human parainfluenza virus type 1 expressing the fusion F protein of the CAN83 strain developed a serum antibody response that efficiently neutralized virus from both lineages and were protected from challenge with either HMPV strain. This result indicates that the HMPV F protein is a major antigenic determinant that mediates extensive cross-lineage neutralization and protection. Both HMPV strains replicated to low titers in the upper and lower respiratory tracts of rhesus macaques but induced high levels of HMPV-neutralizing antibodies in serum effective against both lineages. The level of HMPV replication in chimpanzees was moderately higher, and infected animals developed mild colds. HMPV replicated the most efficiently in the respiratory tracts of African green monkeys, and the infected animals developed a high level of HMPV serum-neutralizing antibodies (1:500 to 1:1,000) effective against both lineages. Reciprocal cross-neutralization assays in which postinfection sera from all three primate species were used indicated that CAN75 and CAN83 are 64 to 99% related antigenically. HMPV-infected chimpanzees and African green monkeys were highly protected from challenge with the heterologous HMPV strain. Taken together, the results from hamsters and nonhuman primates support the conclusion that the two HMPV genetic lineages are highly related antigenically and are not distinct antigenic subtypes or subgroups as defined by reciprocal cross-neutralization in vitro.
Skiadopoulos
Mario H
MH
Respiratory Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Building 50, Room 6511, 50 South Dr., MSC 8007, Bethesda, MD 20892-8007, USA. mskiadopoulos@niaid.nih.gov
Biacchesi
Stéphane
S
Buchholz
Ursula J
UJ
Riggs
Jeffrey M
JM
Surman
Sonja R
SR
Amaro-Carambot
Emerito
E
McAuliffe
Josephine M
JM
Elkins
William R
WR
St  Claire
Marisa
M
Collins
Peter L
PL
Murphy
Brian R
BR
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D000940:Antigenic Variation; D001483:Base Sequence; D002460:Cell Line; D006224:Cricetinae; D003429:Cross Reactions; D004195:Disease Models, Animal; D006801:Humans; D029121:Metapneumovirus / Q000235:genetics* / Q000276:immunology / Q000502:physiology; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D002679:Pan troglodytes; D010222:Parainfluenza Virus 1, Human / Q000235:genetics / Q000276:immunology; D018184:Paramyxoviridae Infections / Q000821:virology; D012137:Respiratory System / Q000821:virology; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication
D000914:Antibodies, Viral; C075739:F protein, parainfluenza virus 1; D014760:Viral Fusion Proteins