Small animals are not susceptible to human immunodeficiency virus infection

Several species of small animals were inoculated at birth or as adults with blood components from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related disorders, or with the human immunodeficiency virus (HIV). No ill effects were noted in rats, hamsters, guinea-pigs, rabbits or musk shrews. Mice inoculated with clinical specimens had a significant incidence of mortality as compared with control groups (18.7% against 5.9%, P less than 0.025). Mice receiving HIV showed an increase in mortality, but it was not statistically significant. Infection of the animals by HIV could not be detected by virological or immunological studies. We concluded that none of these animal species provided a useful model for evaluating HIV infection.

Development of adult T-cell leukemia-like disease in African green monkey associated with clonal integration of simian T-cell leukemia virus type I

Proviral integration of a simian retrovirus highly homologous to human T-cell leukemia virus type I was examined in cellular DNAs extracted from primary peripheral blood lymphocytes of 31 adult African green monkeys (Cercopithecus aethiops) that were seropositive for simian T-cell leukemia virus type I (STLV-I). Among these monkeys, one case with overt leukemia, showing pleomorphic leukemia cells similar to those in human adult T-cell leukemia (ATL), and five cases in a preleukemic state of ATL-like disease were found. Judging from the integration site of the provirus genome, primary lymphocytes of these leukemic or preleukemic cases contained monoclonally proliferated STLV-I-infected cells, whereas lymphocytes of other seropositive monkeys without hematological abnormalities were polyclonal, and those of seronegative monkeys did not contain the provirus. The restriction patterns with PstI ans SstI of most STLV-I proviruses were identical to those of the previous isolate from this species, but in three monkeys there was a deletion of one PstI site. From the correlation of the development of simian ATL-like disease with the monoclonal integration of the STLV-I provirus genome, it should be indicated that STLV-I has similar leukemogenicity to human T-cell leukemia virus type I, and so STLV-I infection in African green monkeys will be useful as an animal model of human ATL.

Hematologic abnormalities similar to the preleukemic state of adult T-cell leukemia in African green monkeys naturally infected with simian T-cell leukemia virus

Studies were made of the hematologic features of 23 adult African green monkeys (Cercopithecus aethiops) naturally infected with simian T-cell leukemia virus (STLV), which is closely related to human T-cell leukemia virus type I. None of the STLV-infected monkeys showed any clinical signs, but their absolute lymphocyte count and percentage of atypical lymphocytes were significantly higher than those of uninfected monkeys. Three STLV-infected monkeys had especially high percentages of atypical lymphocytes. Most of the atypical lymphocytes were small- or medium-sized lymphocytes with a lobulate or convoluted nucleus, and were very similar to the leukemic cells in human cases of adult T-cell leukemia (ATL), while other atypical cells were large lymphoblastoid cells. Both types of atypical cells were positive for Leu2a and Tac antigens, and expressed STLV antigen after short-term culture. These findings suggested the presence of a preleukemic state in these STLV-infected monkeys similar to that seen in human ATL, and indicated the value of this natural infection system as an animal model of ATL in humans.

An erythematous maculopapular eruption in macaques infected with an HTLV-III-like virus (STLV-III)

A cutaneous maculopapular eruption has been previously described in humans infected with HTLV-III/LAV, the etiologic agent of acquired immunodeficiency syndrome. In this study, rhesus monkeys were prospectively examined after infection with an HTLV-III-like virus (STLV-III) to ascertain the incidence and clinical course of gross and histologic alterations of the skin. Between 1-3 weeks after inoculation, 83% of infected animals developed a transient cutaneous maculopapular eruption of the face, groin, and trunk. Histologically, the affected skin was characterized by a superficial perivascular infiltrate of mononuclear cells with associated endothelial cell hypertrophy and degeneration. This eruption preceded opportunistic infections, neoplasms, and other overt clinical signs commonly associated with an immunodeficiency syndrome. The findings suggest that STLV-III infection in the rhesus monkey closely simulates that which occurs in HTLV-III-infected individuals, and that the skin may represent a site of altered immunoregulation early in the course of this disease.