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Arch Med Res. 2003 Sep-Oct;34(5):362-6.

Cross-reactivity between caprine arthritis-encephalitis virus and type 1 human immunodeficiency virus.

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Unidad de Investigación Médica en Inmunología, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, DF, Mexico.



Caprine arthritis encephalitis (CAE) is caused by the lentivirus caprine arthritis-encephalitis virus (CAEV), a member of the Retroviridae family that also includes the human immunodeficiency virus (HIV). Serum of CAEV-infected goats cross-reacts with HIV-1 antigens in enzyme-linked immunosorbent assay (ELISA) tests. We attempted to identify the proteins responsible for this cross-reactivity.


Fifty selected human sera (30 positive, 10 negative, and 10 indeterminate to HIV-1 by Western blot) and 50 selected goat sera (33 positive and 17 negative to CAEV by ELISA) were evaluated. Human and goat sera were tested by Western blot against HIV-1 and CAEV antigens.


Cross-reactivity between surface glycoproteins gp120 (HIV-1) and gp135 (CAEV) was specific. Positive reaction of human sera to CAEV gp135 was more intense than that of goat sera to HIV-1 gp120. Surface glycoprotein sequences of the two viruses were compared by Lasergene software (Dynex Technologies, Inc., Chantilly, VA, USA). Three homologous regions were identified: the first in the internal domain of gp120; the second in the beta3 loop, and still another-with the greatest homology-in a short sequence of the proximal region of the external domain of gp120 between loops beta4 and beta8.


Surface glycoproteins of HIV-1 and CAEV share structural regions essential for viral adsorption and for induction of neutralizing antibodies. Thus, human contact with CAEV eventually could be a possible source of HIV-1 false positive reactions and must be considered in the interpretation of HIV serologic results.

[Indexed for MEDLINE]

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