Humoral immune responses of cats to mammalian type-C virus p30s

Selective antibody reactivity with peptides from human endogenous retroviruses and nonviral poly(amino acids) in patients with systemic lupus erythematosus

OBJECTIVE

To investigate antibody responses to a broad panel of peptides derived from human endogenous retroviruses (HERVs) among unselected patients with systemic lupus erythematosus (SLE).

METHODS

In sera obtained from 69 patients with SLE and healthy blood donors, immunoassay was used to measure levels of antibody against synthetic peptides derived from HERVs, exogenous retroviruses, and nonviral poly(amino acids).

RESULTS

Measurement by immunoassay revealed increased frequencies of antiretroviral antibodies against 2 peptides derived from the env gene of the type C-like class, which includes ERV-9 and HERV-H, and against 2 peptides from the gag region of human T lymphotropic virus type I-related endogenous sequence 1, in patients with SLE. Antibodies to 2 nonviral peptides, polyhistidine and polyproline, were also overrepresented in patient sera. In 1 patient, longitudinal data obtained over a period of 12 years indicated that the concentrations of certain antiretroviral antibodies varied according to disease activity.

CONCLUSION

Reactivity to certain type C HERV-derived antigens was found among patients with SLE. This reactivity could be explained by increased exposure to cross-reactive epitopes from essentially complete type C HERVs.

Increased antiretroviral antibody reactivity in sera from a defined population of patients with systemic lupus erythematosus. Correlation with autoantibodies and clinical manifestations

OBJECTIVE

The implied role of retroviruses in the pathogenesis of murine systemic lupus erythematosus (SLE) led us to study antiretroviral antibodies in a population-based SLE cohort.

METHODS

Immunoassays using whole virus and synthetic peptides were performed on sera from 72 patients with SLE and 88 control subjects.

RESULTS

Reactions with whole baboon endogenous virus occurred more frequently in patients with SLE, and correlated with the presence of anti-RNP and anti-Sm. Some retroviral env and gag peptides, several of which were similar to U1 small nuclear RNP, reacted more strongly in patients with SLE, and their presence was correlated with discoid rash, hematologic disorder, and other symptoms.

CONCLUSION

These results provide circumstantial evidence for involvement of retroviruses in the pathogenesis of human SLE; further studies should be carried out using other techniques for measurement of retroviral expression.

Analysis of the virogenes related to the rhesus monkey endogenous type C retrovirus in monkeys and apes

Molecular hybridization studies were carried out by using a [3H]complementary DNA (cDNA) probe to compare the endogenous type C retrovirus of rhesus monkeys (MMC-1) with other known retroviruses and related sequences in various primate DNAs. The genomic RNA of the endogenous type C retrovirus of stumptail monkeys (MAC-1) was found to be highly related to the MMC-1 cDNA probe, whereas the other retroviral RNAs tested showed no homology. Related sequences were found in Old World monkey DNAs and to a lesser extent in gorilla dn chimpanzee DNAs. No homology was detected between MMC-1 cDNA and DNA of gibbon, orangutan, or human origin. Restriction endonuclease analysis of genomic DNA indicated that many of the several hundred sequences related to MMC-1 in rhesus monkey DNA differed from that integrated into DNA of infected canine cells. Gorilla and chimpanzee DNAs contained a specific restriction endonuclease fragment of the MMC-1 genome.

FeLV epidemiology in Los Angeles cats: Appraisal of detection methods

We investigated the reliability of the fixed cell indirect fluorescent antibody (IFA) peripheral blood smear test as an index of systemic infection with FeLV. Positive results with this test were found to correlate well with detectable FeLV p30 antigen in bone-marrow smears by IFA, in serum and tissue by competition immunoassays, and with type-C particles in bone marrow or spleen by electron microscopy. Most cats with lymphoma, anemia or infectious peritonitis were positive for FeLV and showed a poor or absent antibody response to FeLV p30, gp70, and FOCMA antigens. Most older cats with lymphoma, carcinoma, or sarcoma were negative for FeLV expression and also lacked these FeLV-related antibodies. Detectable immunologic response to FeLV p30 and gp70 proteins and a high-titered FOCMA antibody response were generally restricted to certain healthy cats exposed to FeLV. Antibody to endogenous RD-114 viral p30 and gp70 was not detected in any of a large number of feline sera tested. The prevalence of FeLV-related diseases and immunologic responses to FeLV in healthy cats was directly correlated with the degree of FeLV exposure. By using the IFA blood smear and FOCMA antibody tests one can monitor the horizontal spread of FeLV in multi-cat household and accurately predict the FeLV disease susceptibilty or resistance of individual cats in each environments.