Search

Retroviruses closely related to the human T-cell leukaemia/lymphotrophic virus type I (HTLV-I) have been detected in several, non-human, primate species. These retroviruses are called simian T-lymphotrophic virus type I (STLV-I). Infection with STLV-I has been associated with lymphoma and leukaemia in macaques, baboons, African green monkeys and gorillas. However, no STLV-I infection has been detected in New World primates, although STLV-II has been detected in spider monkeys. When sera from 10 species of non-human primates maintained at the Institute of Primate Research were screened for STLV-I infection, anti-STLV-I antibodies were detected in 12%, 12%, 23% and 38% of the olive baboons, yellow baboons, African green monkeys and lowland Sykes' monkeys, respectively. Western-blot studies confirmed these results. To date, no clinical disease has been linked with STLV-I infection in these colonies. The relatively high prevalence of anti-STLV-I antibodies in these non-human primates offers an opportunity for studies on the transmission, phylogenetic relationships and natural history of STLV-I in primate colonies.

Sera (165 samples in 1988 and 66, follow-up samples in 1989) were collected from olive baboons, African green monkeys, Syke's monkeys and grey mangabeys kept in a semi-free, breeding colony at the Institute of Primate Research (IPR) in Nairobi, Kenya. The levels of antibodies to simian T-lymphotropic virus (STLV) or simian immunodeficiency virus (SIV), and the reactivity patterns of positive sera to various lentivirus subgroup antigens, were then determined. The results of tests using enzyme-immunoassay kits were confirmed by western blots. The prevalence of antibodies which reacted with the Kenyan SIVagm(KEN) isolate was 28% in the African green monkeys tested and 34% in the Syke's monkeys. STLV seroprevalence was 25% in the African greens and 20% in the Syke's. No antibodies to either SIV or STLV were detected in the olive baboons or grey mangabeys. More SIV-positive samples were detected in western blots when SIVagm(KEN) was used as antigen than when SIVagm(CAR014), a geographically distinct isolate from the Central African Republic, was used. However, SIVagm(KEN)-positive sera were more reactive against SIVagm(CAR014) than SIVsmm and SIVmac subgroup antigens, indicating that the two isolates from the African green monkey, CAR014 and KEN, remain antigenetically close even though they were recovered in two geographically distinct regions. To date, no clinical disease has been linked with SIV and STLV infection in the African green or Syke's monkeys in the colony. However, the relatively high prevalence of anti-SIV and anti-STLV antibodies in these monkeys offers an opportunity for prospective studies on the transmission and natural history of both viruses in a single colony.

In previous experiments, the sperm-specific isozyme of lactate dehydrogenase (LDH-C) had been purified from mouse testes and shown to suppress the fertility of female baboons by 70% compared to controls. Although these results demonstrated the feasibility of this approach for contraceptive vaccine development, it is not practical to purify enough of the protein from natural sources for human use. Therefore, a need exists to develop a contraceptive vaccine based on synthetic peptides. In the current study, baboon LDH-C cDNA was amplified by the reverse transcriptase-polymerase chain reaction technique. The amino acid sequences of human and baboon LDH-C were 99.3% identical, indicating that the human LDH-C would be an effective antigen in nonhuman primates. The immunodominant epitope of human LDH-C was identified, synthesized, and conjugated to diphtheria toxoid (DT). This construct was used to immunize 15 female baboons; 15 control animals were immunized with DT alone. The fertility of the experimental group was reduced by 75% as compared to the controls (p < 0.02). One year after the last immunization, the contraceptive effect was completely eliminated (no statistical difference between the groups). These results show that a synthetic peptide based on the sequence of human LDH-C is effective in preventing pregnancy in nonhuman primates. The effect is completely reversed 1 yr after the last immunization. The contraceptive effect is not related to serum antibody titers, and human LDH-C is only slightly more effective than mouse LDH-C in female baboons.

Asymptomatic infection with simian immunodeficiency virus (SIV) has been demonstrated in African Sykes' monkeys (Cercopithecus mitis albogularis), and virus isolation confirmed infection with a novel SIV from Sykes' monkeys (SIVsyk). Macaques inoculated with SIVsyk became persistently infected but remained clinically healthy. We utilized polymerase chain reaction amplification to generate a full-length, infectious molecular clone of SIVsyk. The genome organization of SIVsyk is similar to that of the other primate lentiviruses, consisting of gag, pol, vif, vpr, tat, rev, env, and nef. A unique feature is the absence of the highly conserved NF-kappa B binding site in the long terminal repeat. SIVsyk is genetically equidistant from other primate lentiviruses. Thus, SIVsyk represents a new group that is distinct from the four previously recognized primate lentivirus groups: human immunodeficiency virus type 1 (HIV-1), SIV from sooty mangabeys (SIVsmm) and HIV-2, SIV from African green monkeys (SIVagm), and SIV from mandrills (SIVmnd). The genetic differences between SIVsyk and SIVagm, isolates derived from monkeys of the same genus, underscore the potential for other distinct SIVs which have yet to be isolated and characterized.

To document the spontaneous evolution of endometriosis, a repeat laparoscopy was performed in 11 baboons after 10 and/or 12 months. The mean number of endometriotic lesions had increased significantly after 10 months (P less than 0.02) because of a high proportion of new lesions (82%). These implants were mainly subtle (67%) and localized on the uterine peritoneum (58%). Progression of endometriosis did not go beyond revised AFS stage I. Additionally, repeat laparoscopy in 10 baboons with an initially normal pelvis showed an endometriosis incidence of 70% after 10 to 12 months. Remodeling of the lesions was apparent in both groups after 12 months. These results suggest that endometriosis is moderately progressive in the baboon. It is possible that multiple laparoscopies could favor the development of endometriosis.

The histopathology of spontaneous endometriosis was studied on 20 pelvic implants biopsied at laparoscopy in 15 healthy baboons. Endometriosis was confirmed by histopathology in 10 of these animals (66%). Typical (n = 3) and subtle (n = 13) endometriotic lesions were confirmed by histopathology in 100 and 61%, respectively. Suspected disease-bearing lesions (n = 4) were confirmed in 50%. Implants could be classified as active (n = 5), inactive (n = 3), atrophic (n = 2) or stromal endometriosis (n = 3). The histological findings for typical and subtle implants were similar to those reported in humans.

The prevalence of spontaneous endometriosis was investigated by laparoscopy in 52 baboons (Papio anubis and Papio cynocephalus) of proven fertility. Clinical endometriosis was diagnosed in 9 (17%) and 4 (8%) baboons with or without a previous hysterotomy, respectively. Endometriosis was confirmed by histology in 75% of these animals. The 37 endometriotic lesions were classified as typical (13%), subtle (57%), or suspicious (30%); and the percentage of histological confirmation was 100%, 61%, and 50%, respectively. Lesions were found on the uterosacral ligaments and in Douglas' pouch (46%), on the uterine peritoneum and the uterovesical fold (38%), and on uterine-omental adhesions (11%). Only 5% of the lesions were localized on the ovarian ligament, whereas ovarian endometriosis was not found. This study for the first time demonstrates that spontaneous endometriosis occurs in healthy baboons with proven fertility. It also shows that the laparoscopic appearances, the histological aspect, and the localization of the pelvic lesions are comparable to those found in women. We therefore conclude that the baboon is a good animal model for the study of endometriosis.

Analysis of serum samples from 100 wild-caught or colony-born Sykes' monkeys (Cercopithecus mitis) in Kenya revealed that 59 animals had antibodies cross-reactive to human immunodeficiency virus type 2 (HIV-2) and to simian immunodeficiency viruses (SIVs). A lentivirus, designated SIVsyk, was isolated from five of six seropositive asymptomatic Sykes' monkeys, but in four cases isolation was possible only after depletion of CD8+ lymphocytes and cocultivation of the CD4(+)-enriched cell population with peripheral blood mononuclear cells from seronegative Sykes' monkeys. SIVsyk resembled other SIVs and HIVs morphologically, had an Mg2(+)-dependent reverse transcriptase enzyme, and replicated in and was cytopathic for CEMx174 and Sup-T1 cells. SIVsyk differred substantially from other SIVs, however, in that it failed to replicate in normal human, mangabey, and macaque peripheral blood mononuclear cells and serum from seropositive Sykes' monkeys immunoprecipitated env antigens from HIV-1 as well as from HIV-2, SIVsmm, and SIVagm. These data demonstrate a high prevalence of natural infection in Sykes' monkeys in Kenya with a lentivirus that appears to be unique with respect to its host range and antigenic cross-reactivity.

Antibodies to sperm and testicular autoantigens are a hallmark of vasectomy-induced murine autoimmunity. We generated five autoimmune monoclonal antibodies with spleen cells from nonimmunized but vasectomized BDF1 male mice as fusion partners in two experiments. Four of the antibodies, designated Vx 4, Vx 8, Vx 10, and Vx 23, recognize, as determined by fluorescence microscopy, topographically restricted sperm-specific antigenic determinants that appear in the germinal epithelium as spermatogenesis progresses. Antibodies Vx 8 and Vx 10 identified 60,000- and 97,000- dalton, mouse-specific sperm antigens restricted to the anterior acrosome and posterior acrosome, respectively. Antibody Vx 23 identified a 35,000- to 40,000- dalton antigen on the midpiece and postacrosomal regions of epididymal mouse sperm. The antigenic target of antibody Vx 4 on the midpiece region could not be identified with the Western blot technique. Both Vx 4 and Vx 23 cross-reacted with human, rabbit, and monkey sperm; immunofluorescence revealed that they were bound onto the midpiece region. By immunofluorescence, a single clone (Vx 24) distinctly reacted with the nuclei of somatic and testicular germ cells but not the nuclei of sperm. The isolation of this antinuclear autoantibody raises questions about the development of nonsperm-specific autoantibodies after vasectomy in the mouse.

A monoclonal antibody to an antigen in the human germ cell membrane did not agglutinate or immobilize sperm but inhibited binding and penetration of zona-free hamster ova by human sperm and blocked murine fertilization in vitro. The antibody, of the 2a subclass of immunoglobulin G, was germ cell-specific but not species-specific. It recognized a single antigen of 23 kilodaltons that has been isolated from human germ cells. This fertilization antigen, located on the postacrosome , midpiece, and tail of human sperm, is a glycoprotein of testicular origin associated with some types of human involuntary immunoinfertility .

Monoclonal antihuman sperm antibodies were used to study the surface antigens of sperm from man, monkey (Macaca mulatta), dog, rabbit, bull and mouse. Quantitative absorption results indicate some of the antibodies cross-react with sperm of all the species tested while three recognized determinants were unique to the human sperm. These reactions were sperm-specific since no cross-reactivity was observed with somatic tissue from human and mouse. In the indirect immunofluorescence test, monoclonal antibodies MA1 and MA4 recognize antigenic determinants which appear within the mouse testis during spermatogenesis and are present on the acrosome and mid-piece sperm regions, respectively, of the species tested. MA2 reacted diffusely with the acrosome of human and monkey sperm only. In contrast, MA3 had a speckled acrosomal staining pattern reacting only with human sperm. Antibodies MA5 and MA6 were also specific for human sperm, binding to the equatorial and tail regions. Live human and monkey sperm were agglutinated and immobilized by MA1 but only immobilized by MA2 . With the Western blot technique, human sperm antigens of approximately 84,000, 240,000, 30,000 and 71,000 daltons were identified by antibodies MA1 , MA3 , MA4 and MA5 , respectively. An acrosomal antigen of approximately 82,000 daltons present on both bull and mouse sperm was identified by MA1 . Antibody MA4 , in turn, identified at 28,000-dalton mouse sperm antigen and a 35,000- to 37,000-dalton antigen present on the midpiece of bull sperm.

Three monoclonal antibodies (BM2, BM3 and BM4) were obtained from two hybridomas produced after murine immunization with total placental cell dispersion obtained from animals at day 33 of gestation. Immunohistochemical studies showed that antigens recognised by these three antibodies were located on villous trophoblast of fixed placental sections at day 33 of pregnancy. Other fixed normal baboon tissues tested were non-reactive with these antibodies. Monoclonal antibody BM2 was found to stain villous cytotrophoblast; BM3 and BM4 reacted with syncytiotrophoblast but with different staining characteristics. Immunoblot studies showed that BM2, BM3 and BM4 antibodies recognized antigens corresponding to 30.9, 31.3 and 42.3 kDa, respectively.

Mouse monoclonal antibodies were produced against simian immunodeficiency virus (SIV) from the African green monkey (SIVAGM). The antibodies reacted with the transmembrane protein of all five SIVAGM isolates but not with those of SIVs from the rhesus macaque and mandrill or of human immunodeficiency virus type 1 or type 2, indicating that they recognize a species-specific epitope strongly conserved in SIVAGM. The transmembrane proteins of several SIVAGM isolates were found to vary in molecular size, even in the deglycosylated form after N-glycanase treatment, indicating heterogeneity of the SIVAGM isolates.

Infection with a simian retrovirus (STLV-I) closely related to human T-lymphotropic virus type I (HTLV-I) was investigated in non-human primates living in their native countries in Africa and Asia. Serum antibodies cross-reacting with HTLV-I antigens were detected in 85 of 567 non-human primates of 30 species. Seropositive animals were found among African green monkeys, olive baboons, Sykes' monkeys, mandrills and patas monkeys in several countries in Africa, and cynomolgus monkeys, Celebes macaques and siamangs in Indonesia. The frequency of seropositivity was much higher in adult than in young African green monkeys, cynomolgus monkeys and Celebes macaques. STLV-Is were isolated by establishing II lines of virus-producing lymphoid cells in the presence of interleukin-2 from 5 species of seropositive non-human primates, i.e. the African green monkey, Sykes' monkey, Celebes macaque, cynomolgus monkey and siamang. All these cell lines had T-cell markers and Tac antigen, and the cell lines from the African green monkey and Sykes' monkeys were Leu2a+ while those from other species were Leu3a+. These cell lines expressed viral antigens reacting with human sera from adult T-cell leukemia (ATL) patients and monoclonal antibodies (MAbs) against p19 and p24 of HTLV-I core proteins, and produced virus particles having RNA-dependent DNA polymerase activity. Cellular DNAs from these cell lines contained provirus sequences homologous to HTLV-I, shown by Southern blot hybridization. The restriction patterns of these provirus genomes were different from those of HTLV-I and were also dissimilar in the different species.