Serological assays for the detection of human andes hantavirus infections based on its yeast-expressed nucleocapsid protein.
BACKGROUND
The objective of the study was to develop and evaluate IgM and IgG ELISAs and an IgG Western blot test for the serological detection of human infections with Andes virus (ANDV), the major cause of hantavirus cardiopulmonary syndrome (HCPS) in South America.


METHODS
The entire nucleocapsid (N) protein-encoding sequence of ANDV (strain AH-1) was cloned and expressed in the yeast Saccharomyces cerevisiae. The polyhistidine-tagged recombinant N (rN) protein of ANDV was purified by nickel-chelation chromatography and characterized by its reactivity with different N-specific monoclonal antibodies. To detect an antibody response directed against ANDV in humans, indirect IgM and IgG ELISAs and an IgG Western blot test based on ANDV rN antigen were developed. The evaluation of the tests was performed using a negative serum panel and 63 blinded sera from Argentina and Chile, containing acute-phase and convalescent sera from HCPS patients.


RESULTS
The specificities and sensitivities for the IgM and IgG ELISAs were demonstrated to be very high. The IgG ELISA data were confirmed by the IgG Western blot assay based on the same rN antigen. Almost all anti-ANDV-positive sera reacted to higher endpoint titers with N protein of ANDV than with those of Sin Nombre, Laguna Negra or Puumala virus. The cross-reactivity of anti-ANDV-N IgG-positive sera to rN proteins of other hantaviruses was found to be increased with time after the onset of HCPS.


CONCLUSIONS
The high sensitivity of the novel assays should facilitate early diagnosis of ANDV infections and might contribute to a successful treatment of HCPS patients.
Schmidt
Jonas
J
Institute of Virology, Charité School of Medicine, Berlin, Germany.
Meisel
Helga
H
Capria
Silvana G
SG
Petraityte
Rasa
R
Lundkvist
Ake
A
Hjelle
Brian
B
Vial
Pablo A
PA
Padula
Paula
P
Krüger
Detlev H
DH
Ulrich
Rainer
R
D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000276:immunology / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006476:Orthohantavirus / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification*; D018778:Hantavirus Infections / Q000175:diagnosis*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D019590:Nucleocapsid Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D012680:Sensitivity and Specificity; D012703:Serotyping; D013020:South America / Q000453:epidemiology
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000956:Antigens, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D019590:Nucleocapsid Proteins; D011993:Recombinant Fusion Proteins