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Title: IDENTIFICATION OF HYPERVARIABLE AND CONSERVED REGIONS IN THE SURFACE ENVELOPE GENE IN THE BOVINE LENTIVIRUS

Author
item SUAREZ, DAVID - IOWA STATE UNIVERSITY
item Whetstone, Cecelia

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bovine lentivirus causes a lifelong infection of beef and dairy cattle. The virus is difficult to detect, so its role in chronic disease processes in cattle is uncertain. A laboratory adapted bovine lentivirus that was found over 20 years ago has been used in development of current diagnostic procedures for the virus, and in most research that has been done on the virus. Recently, several unstudied lentiviruses were obtained from infected cattle. A viral gene responsible for making a protein found on the surface of the virus was examined. That gene was bigger in viruses that were found recently than in the laboratory adapted virus. This means that the protein on the surface of the newly found viruses is different than the same protein on the laboratory virus. This finding has impact on diagnostic procedures used to detect lentivirus. It may be necessary to devise new diagnostic procedures that compensate for changes that appear to ooccur in the virus. The long-term benefit of this research is improved diagnostic procedures that enhance detection of lentivirus and that will allow a more accurate assessment of the viruses role in disease of cattle. Ultimately, the improved diagnostic tests will benefit cattle producers.

Technical Abstract: The surface envelope (SU) of nine different isolates of the bovine lentivirus were compared for nucleotide and deduced amino acid (aa) sequence diversity. Analyses were done both on isolates derived from the original reference strain, R29, and on field isolates of bovine lentivirus. Six conserved and seven hypervariable regions were identified. Many of the ehypervariable regions were located in areas predicted to be on the surface of the SU protein. The SU gene comparison among all isolates showed up to a 50% aa sequence divergence. When a conserved region of the reverse transcriptase gene was compared among 8 of the isolates, there was less than 12% aa sequence divergence. When comparing all isolates, the greatest size differences in the SU gene are observed in the second variable region (V2) with up to 104 aa difference between the largest and smallest variant. R29-106, an infectious molecular clone of the original isolate of bovine lentivirus, has an 87 bp deletion in V2 as compared to prototype isolate R29-127. All R29-derived isolates sequenced for this study had a SU gene size similar to R29-106. The four field isolates sequenced for this study had SU genes larger than R29-127. R29-derived isolates may not be representative of bovine lentivirus currently detected in the field.