Frequent detection of reviraemia in ducks persistently infected with avian leukosis retroviruses.
Ducks intraembryonally infected with avian leukosis viruses of subgroup C (ALV-C) were followed for a long period (up to 6.8 years), and the viraemia and production of virus-neutralizing antibodies were measured. In three independent experiments comprising ducks inoculated with uncloned and/or molecularly cloned ALV-C, we found that after the elimination of primary post-hatching viraemia, reviraemia could be detected in 60-70% of infected animals. Based on the course of viraemia, the individual ducks were assigned to four different groups: Group I (no reviraemia), Group II (one transient reviraemic period), Group III (one persistent reviraemic period), Group IV (fluctuating reviraemia). In comparison to sera from ducks included in Group I and/or II, a significant decrease in neutralizing activity of sera from animals comprised in Group III and/or IV was observed. Two out of four reviraemic viruses were not neutralized by antiserum against ALV-C, instead their infectivity was enhanced. Long-term follow-up of the cell-associated virus revealed that its rescuability by cocultivation with chicken embryo fibroblasts fluctuated in about 50% of animals. In the reviraemic phase of infection, integrated proviruses could be detected by Southern blotting in a majority of tissues examined. Our data document that many features recognized in lentiviruses are valid also for oncoviruses transmitted to heterologous hosts and substantiate further the suitability of ALV-C-infected ducks as a model for studying persistent retroviral infection.
Geryk
J
J
Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Machon
O
O
Hák
R
R
Trejbalová
K
K
Hejnar
J
J
Plachý
J
J
Karakoz
I
I
Svoboda
J
J
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001353:Avian Leukosis / Q000097:blood / Q000276:immunology / Q000821:virology*; D001354:Avian Leukosis Virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis; D004372:Ducks / Q000196:embryology; D007700:Kinetics; D009500:Neutralization Tests; D011533:Proviruses / Q000235:genetics; D013997:Time Factors; D014018:Tissue Distribution; D014766:Viremia / Q000821:virology*
D000914:Antibodies, Viral; D004279:DNA, Viral