Mesenchymal neoplasms associated with type D retroviruses in macaques

The type D subfamily of retroviruses contains five distinct viruses which are found in New and Old World monkeys. The retroviruses found in Old World macaque (genus Macaca) monkeys are exogenous to the species and upon injection induce a fatal simian acquired immune deficiency syndrome (SAIDS). Two serotypes of type D virus, SAIDS retrovirus types 1 and 2 (SRV-1 and SRV-2), are found in captive macaques in primate centres in the United States. In addition to SAIDS, two neoplasms, retroperitoneal fibromatosis (RF) and subcutaneous fibrosarcomas (SF), have been found in macaques with type D retrovirus-induced SAIDS. Only SRV-2 is found in association with RF, and only about 35% of SRV-2-infected macaques develop RF. SF is found in association with both serotypes, but less than 5% of infected monkeys develop SF. The RF in macaques is potentially a model for human disease since the lesions in macaques are similar to the idiopathic RF described in humans. Thus far, RF has not been found in species other than macaque or man. The complete sequence of three type D retroviruses is known. Importantly, no oncogenes are present in the viral genome. Therefore, the mechanisms for tumour induction which involve immunosuppressive or genetic properties of the virus that are distinct from classic oncogenes must be considered.     

Simian AIDS--evidence for a retroviral etiology

This paper reviews the major features of a simian model of acquired immunodeficiency ('SAIDS'), SAIDS occurs endemically in colonies of macaque monkeys in the United States and resembles AIDS in humans in overall clinical manifestations, pathology, and immune deficiency. An infectious type D retrovirus, related to but distinct from the Mason-Pfizer monkey virus, has been identified as the primary cause of SAIDS. The relevance of these findings for human AIDS is discussed.     

Inapparent carriers of simian acquired immune deficiency syndrome type D retrovirus and disease transmission with saliva

Simian acquired immune deficiency syndrome (SAIDS) type D retrovirus (SRV) was isolated from saliva, urine, and peripheral blood mononuclear cells of a 6-year-old healthy rhesus monkey (Macaca mulatta) seronegative for antibodies to human T-lymphotropic virus (HTLV) type I, HTLV type III, and simian T-lymphotropic virus type III (STLV-III), identified as an inapparent SAIDS carrier in retrospective epidemiologic studies. This animal was linked to 34 cases of SAIDS over a 3-year period. Two juvenile rhesus monkeys inoculated iv with the SRV-containing saliva from this carrier became persistently infected with the retrovirus and developed SAIDS after 4-6 weeks. Both animals seroconverted to SRV, but neither had detectable preinoculation or postinoculation antibodies against HTLV type I, HTLV type III, or STLV-III. One of these animals died of SAIDS with disseminated cytomegalovirus infection after 24 weeks, and the other remains alive with persistent SRV viremia, generalized lymphadenopathy, and splenomegaly after a transient immunosuppression. Major clinical and pathological features associated with the newly described STLV-III were not observed. SRV was subsequently identified in saliva of 2 additional healthy carriers as well as monkeys with SAIDS. The findings of a carrier state in SAIDS and evidence for saliva transmission of the probable causative virus further support the usefulness of this animal model of nononcogenic immunosuppressive retroviral disease.     

An immunopathologic evaluation of lymph nodes from monkey and man with acquired immune deficiency syndrome and related conditions

Morphology and immunostaining of lymph nodes taken from rhesus monkeys and man are compared. The monkeys were inoculated with biologic materials known to transmit simian acquired immune deficiency syndrome (SAIDS) and the human biopsies were obtained from homosexual men with persistent generalized lymphadenopathy syndrome or acquired immune deficiency syndrome (AIDS). The lymph nodes from monkey and man share common immunohistochemical features, ranging from exhuberant follicular hyperplasia to lymphocyte depletion stage. The follicular hyperplasia differed from reactive controls by the larger follicular size and disorganization within the follicular centers as well as an increase in the number of cells with the T suppressor/cytotoxic phenotype. The lymphocyte depletion stage showed a loss of reactive follicles and small T lymphocytes with a predominance of mature monocytes/macrophages. Most monkeys and humans with the lymphocyte depletion morphology fulfilled the case definitions for AIDS and SAIDS while those with follicular hyperplasia usually had 'prodromal' findings. The simian agent is associated with alterations in lymph node morphology and immunostaining which parallel the changes seen in spontaneous human cases supporting a similar pathogenesis for AIDS and SAIDS.     

Natural history of endemic type D retrovirus infection and acquired immune deficiency syndrome in group-housed rhesus monkeys

A 2.5-year epidemiologic study of a breeding group of rhesus monkeys (Macaca mulatta), which is a focus of endemic simian acquired immunodeficiency syndrome (SAIDS), demonstrated a strong association between the occurrence of SAIDS and infection with a type D retrovirus, SAIDS retrovirus serotype 1 (SRV-1). Of 23 healthy "tracer" juvenile rhesus monkeys, 19 (83%) died with SAIDS within 9 months of introduction into the resident SAIDS-endemic population. In contrast, 21 healthy "sentinel" juvenile rhesus monkeys placed in the same outdoor enclosure but denied physical contact with the SAIDS-affected group by a 10-foot-wide "buffer zone" remained free of SRV-1, SRV-1 antibody, and disease for 2.5 years. The SAIDS-specific mortality rate was significantly higher in juveniles than in adults. In repeated serologic testing, the overall prevalence of SRV-1 antibody ranged from 68 to 85%. Antibody prevalence increased with age. Seroconversion was found to be a poor indicator of infection rate, as approximately 50% of virus-positive juvenile monkeys had no antibody detectable by enzyme-linked immunosorbent assay. Repeated viral isolations from all animals revealed 1) SRV-1 viremia with clinical SAIDS; 2) persistent viremia and viral shedding in apparently healthy animals; 3) transient viremia and clinical recovery; 4) intermittent viremia, suggesting activation of latent infections; and 5) viremia in a 1-day-old infant, suggesting transplacental transmission. The prevalence of SRV-1 antibody in SAIDS-free breeding groups of rhesus monkeys was 4%. The seroprevalence of antibodies against human T-cell leukemia virus type 1 (HTLV-1), human immunodeficiency virus (HIV), and simian immunodeficiency virus (SIV; formerly STLV-III) was uniformly low or absent in both SAIDS-free and SAIDS-affected groups of rhesus monkeys, demonstrating that these retroviruses are not etiologically linked to SAIDS at the California Primate Research Center.     

Effect of the Fv-1 gene on leukemia virus in mouse cell heterokaryons

The effect of the Fv-1 mouse gene restriction of N- and B-tropic mouse leukemia viruses was examined by determining the fate of the viruses in heterokaryons of permissive and non-permissive cells. Virus expression in cultures of fused cells was analyzed by simultaneous autoradiography and fluorescent antibody assay, which permitted the detection of virus-induced proteins specifically in heterokaryons or cells of either parental type. Heterokaryons were found to dominantly restrict both N- and B-tropic virus, but not NB-tropic virus which infects either cell type with equal efficiency. Fusion of permissive cells with non-permissive cells at increasing intervals after infection showed that the restriction affects some virus function within at least 12 h of infection. These results indicate that the Fv-1 gene locus, or gene product, affects some post-penetration events required for virus protein synthesis.     

Role for Raf in the entry of viruses associated with AIDS (review)

The biology of acquired immune deficiency (AIDS) is yet to be completely understood partly because it is complicated by the manifestation of various viral infections and associated pathogenesis. Virus entry into target cells is a key step in the virus replication cycle which is characterized by intricate and complex interactions between virus and host cells. Analyses of virus entry are always hampered to some extent due to the inability to mimic in vivo conditions. Emphasis has been placed on understanding what the virus does during the entry process; for example the signaling it mediates during entry, or identifying the cellular receptors with which the virus interact. Often, the role of the cellular environment that is critical for the complex process of virus uptake has taken a back stage. Interestingly, most of the viruses associated with AIDS cause tumors. In a recently concluded study, we identified a role for intracellular oncogenic (Raf) signaling in human herpesvirus-8 (HHV-8/KSHV) infection of target cells. In this review we present an update on entry of various viruses commonly associated with AIDS and yet another novel way of analyzing virus entry.     

Narrow host range of AIDS-related retroviruses (YU-1, 2, 3, 4) isolated from Japanese hemophiliacs: inability to infect H9, Molt-4, and MT-4 cells

Infectivity was assayed by infecting human T-lymphocytes, H9, Molt-4, and MT-4 cells with different strains of AIDS viruses (HTLV-III, LAV, ARV, and YU viruses). Human T-lymphotropic virus type-III (HTLV-III), lymphadenopathy-associated virus (LAV), and AIDS-associated retrovirus (ARV) were able to infect all kinds of target cells tested and to induce virus-specific antigens, whereas Japanese isolates, YU viruses, infected only interleukin-2-dependent human T-lymphocytes. Long-term propagation of the YU viruses and pretreatment of the cells with Polybrene did not allow the YU virus to produce viral antigens by infecting H9, Molt-4, and MT-4 cells. Thus, YU viruses have a rather narrow host range as compared with HTLV-III, LAV, and ARV. These different infectivities may be reflected in the progress and symptoms of AIDS in vivo.     

Oncornavirus-like particles in squirrel monkey (Saimiri sciureus) placenta and placenta culture.

Oncornavirus-like particles similar in morphology to type D particles were observed in 1 of 2 squirrel monkey (Saimiri sciureus) placentas. Intracytoplasmic type A particles, immature virus particles, and mature viruses with eccentric or occasionally centric nucleoids were associated with placental syncytiotrophoblasts. A spike layer typical of type B viruses was not detected in viral envelopes. Onvornaviruses, identical to those previously isolated from squirrel monkey tissues and similar to Mason-Pfizer monkey virus, were seen in cultures derived from the virus-positive squirrel monkey placenta cocultivated with a mink lung culture. The major morphologic difference between the in vivo and the in vitro squirrel monkey virus was in the nucleoid position of mature virus particles.     

Kaposi sarcoma in Okinawa.

BACKGROUND. The authors encountered six patients with Kaposi sarcoma in Okinawa; one was classic type, two were associated with adult T-cell leukemia (ATL), one was with multiple myeloma, and two were with acquired immune deficiency syndrome (AIDS). In the classic type, many nodular lesions were seen on the skin of the extremities and a few on the trunk, some of which were ulcerated. Most lesions regressed in 1.5 years. In four other patients (three without AIDS and one with AIDS), many plaques and a few nodular lesions were seen on the trunk, face, and extremities. The other patient with AIDS showed Kaposi sarcoma only in the lymph nodes and perineural tissues in the abdomen. METHODS. Immunohistochemical and lectin histochemical studies were done on deparaffinized sections and on cells cultured from small pieces of tumor mass from the classic type Kaposi sarcoma. Isolation of viruses from tumor tissue was also attempted. RESULTS. Large numbers of endothelial cells lining irregular vascular spaces, and some spindle cells showed positive reactions for Factor VIII-related antigen, Ulex europaeus 1 (UEA-1) (E.Y. Labs, Inc., San Mateo, CA), Griffonia simplicifolia (GS-1) (E.Y. Labs, Inc.) lectins, and epidermal growth factor (EGF) receptor antigen. Cytomegalovirus (CMV), hepatitis B, herpes simplex virus (HSV) 1 and 2, papillomavirus antigens, and human immunodeficiency virus (HIV) p24 core antigen were not seen in any patients, except in the patient with AIDS in whom CMV was demonstrated in tissues adjacent to the tumor (Patient 6). In cell culture, elongated spindle cells proliferated in plate and also in three-dimensional cultures. The cells were positive immunohistochemically for Factor VIII-related antigen and EGF receptor. They also stained lectin histochemically with UEA-1 and GS-1. Tube formations were demonstrated by electron microscopic study. CONCLUSIONS. Six cases of Kaposi sarcoma have been diagnosed within a short time span where this condition has previously been said to be rare. The studies suggest a vascular endothelial cell origin and growth factor regulated growth for this tumor.     

Antibody to the AIDS virus in Kaposi's sarcoma in Nigeria

The present study has investigated whether Kaposi's sarcoma (KS) in Nigeria is associated with infection with the AIDS virus variously called human T-cell lymphotropic virus type III (HTLV-III), lymphadenopathy/AIDS virus (LAV), and AIDS-associated retrovirus (ARV). Serum samples from 40 KS patients, 30 patients with malignant melanoma of the foot (contemporaneous controls), and 50 normal nontumour-bearing controls were tested for anti-AIDS virus antibody by enzyme-linked immunosorbent assay (ELISA). The assay consistently and reproducibly failed to show seropositivity in all the patients and controls. These results show that Kaposi's sarcoma in Nigeria is not associated with infection with the AIDS virus and that the virus is not endemic in this region.     

Growth regulation of simian and human AIDS-related non-Hodgkin's lymphoma cell lines by TGF-β1 and IL-6

Background  

AIDS-related non-Hodgkin's lymphoma (AIDS-NHL) is the second most frequent cancer associated with AIDS, and is a frequent cause of death in HIV-infected individuals. Experimental analysis of AIDS-NHL has been facilitated by the availability of an excellent animal model, i.e., simian Acquired Immunodeficiency Syndrome (SAIDS) in the rhesus macaque consequent to infection with simian immunodeficiency virus. A recent study of SAIDS-NHL demonstrated a lymphoma-derived cell line to be sensitive to the growth inhibitory effects of the ubiquitous cytokine, transforming growth factor-beta (TGF-beta). The authors concluded that TGF-beta acts as a negative growth regulator of the lymphoma-derived cell line and, potentially, as an inhibitory factor in the regulatory network of AIDS-related lymphomagenesis. The present study was conducted to assess whether other SAIDS-NHL and AIDS-NHL cell lines are similarly sensitive to the growth inhibitory effects of TGF-beta, and to test the hypothesis that interleukin-6 (IL-6) may represent a counteracting positive influence in their growth regulation.     

Studies on the rescue of a defective MSV genome using leukemogenic viruses from different sources

In vivo rescue of a defective MSV genome from isolated cells of the rat neoplasm MSB-1 was achieved by simple and direct methods: (1) by mixing of tissue-culture-grown MSB-1 cells with tissue extracts or with leukemogenic virus preparations prior to intramuscular inoculations into neonatal mice; and (2) by direct inoculations of these cells into neonatal or older mice previously infected with leukemogenic viruses or infected with vertically transmitted virus. Serial in vivo transfers of the rescued pseudotype viruses MSV (MLV) and MSV(RLV) were accomplished with ease but difficulty was experienced with those pseudotype viruses rescued with leukemogenic viruses of the Gross type, MSV (GLV) from C58, C3Hf/Fg and SJL strain leukemic mice; MSV (RadLV) rescued through the use of extracts from X-ray-induced leukemias of C57BL/Ka mice behaved in a similar manner to the MSV(GLV) pseudotype viruses. When tumor induction occurred, the lesions were of similar morphology no matter what the pseudotype virus inoculated and were classified as “atypical”; granulomas.     

Possible cofactors for the development of AIDS-related neoplasms

Because of the various neoplastic manifestations of human immunodeficiency virus (HIV) and the variable period between HIV infection and the development of tumors related to acquired immunodeficiency syndrome (AIDS), it is possible that certain behaviors, toxins, genes, or infectious agents--particularly viruses--may act as cofactors in the pathogenesis of AIDS-related neoplasms. Most epidemiologic and laboratory investigations of possible cofactors have been directed toward Kaposi's sarcoma (KS), by far the most common AIDS-related tumor and one closely associated with male homosexual lifestyle in the U.S. Nonetheless, epidemiologic investigations of putative associations have not demonstrated any clear association between KS and particular viruses. Furthermore, laboratory investigations, both serologic and molecular/genetic, have failed to definitively implicate as cofactors for KS these viruses: cytomegalovirus, Epstein-Barr virus (EBV), herpes simplex viruses, pathogenic human papillomaviruses, or human herpes virus type 6. Investigations of a suggested association between EBV and AIDS-associated non-Hodgkin's (B cell) lymphomas (NHLs) have also been inconclusive. However, HIV may act as a cofactor in accelerating the development of hepatitis B-associated hepatocellular carcinoma. In summary, viral or other cofactors have not been definitely identified as cofactors in AIDS-related tumors.     

Characteristics of murine C-type viruses. IV. The virus produced by Ehrlich tumor cells and it hybrids with mouse L cells

The infectious properties of viruses produced by Ehrlich tumor cells (E), the A9 subline of mouse L cells (L), their hybrids (EL₀ and EL) and high-malignant sublines of the low-malignant hybrid line (EL_m) were investigated. The infectivity assays were antigen induction on JLS-V9 cells, antigenic conversion and focus induction on S + L - cells (D56 subline) and focus formation on BALB/3T3 cells. The E and L viruses, produced by the parental cells, were detected in the JLS-V9 test but were distinguished in S + L - and BALB/3T3 cells. The L virus was focus-positive, the E virus focus-negative (BALB/3T3). For antigenic conversion, the L virus was negative and the E virus positive (D56). The hybrid cell line, tested on several occasions after the hydridization event, produced viruses with characteristics similar to both E and L viruses, regardless of the complete or reduced chromosome numbers. The malignant sublines selected from the hybrid showed preferential loss of the A9 parent-derived biarmed chromosomes. One of these lines produced virus (EL_m) with infective properties similar to those of the E virus. This suggests that the virus produced by a particular cell line is determined by the cell genome. Another malignant subline was found to be negative for production of infectious virus in all three indicator systems.     

Molecular epidemiology of Epstein-Barr virus (EBV) in EBV-related malignancies

The prevalent strain of Epstein-Barr virus (EBV) in EBV-related malignancies and in healthy adults in Southern Japan was examined by means of polymerase chain reaction (PCR) and/or restriction fragment length polymorphism (RFLP) analysis. In EBV-related gastric cancers, 51/73 cases were subtype A, 4 were subtype B and the EBNA-2 region was not amplified in 18 cases. Sixty-three were wild-type F, and only one was variant “f”. Sixty-one cases had type C and 2 type D. EBNA-2 subtype A was found in 10/12 EBV-related T/NK-cell lymphomas, and 11 samples harbored the wild-type F. Neither subtype B nor the “f” variant was detected. Type C EBV was found in 8 cases and type D in 3 specimens. Two Japanese nasopharyngeal carcinomas (NPC) harbored subtype A with wild-type F and type C. Throat washings from healthy adults harbored wild-type F virus in 60/153 cases, and 25 of these samples were EBNA-2 subtype A. Type C viruses were detected in 92% of cases and type D in 7.4%. Therefore, the prevalent strain in EBV-related malignancies in Southern Japan was the same as in the healthy population in this geographical region. Int. J. Cancer 72:72–76, 1997. © 1997 Wiley-Liss Inc.     

Presence of human beta- and gamma-herpes virus DNA in Hodgkin's disease

Herpes viruses have been implicated in the etiology of Hodgkin's disease (HD). We studied the prevalence of human cytomegalovirus (CMV), human herpes viruses type-6 (HHV-6), type-7 (HHV-7) and type 8 (HHV-8) DNA in up to 88 Hodgkin's disease biopsies in comparison to Epstein-Barr virus (EBV) DNA by polymerase chain reaction (PCR). Non-Hodgkin lymphomas (NHL) and reactive lesions served as controls. CMV and HHV-6 were found in 8/86 (9%) and 11/88 (13%) HD cases, respectively, by nested primer PCR. Except for three cases harbouring HHV-6 type-B, only HHV-6 type-A was detected in HD. HHV-7 was observed by nested PCR in 33/88 (38%) HD cases and was already detectable in 15/88 (17%) HD cases by a single-round PCR indicating elevated virus copy numbers. Seven of these cases showed co-infection with HHV-6, and 11 cases were found to contain EBV DNA. 7/8 CMV-positive HD cases also harboured EBV DNA. HHV-8 DNA was not detected by single round or nested PCR in any HD case investigated. Thus, CMV, HHV-6, and HHV-7 were present in small proportions of HD cases, with frequent co-infection of HHV-6 and HHV-7, and frequent association with EBV. In contrast to EBV, beta-herpes viruses are therefore unlikely to have a role in the aetiology of HD. Rather, the presence of these viruses seems to reflect impaired immunological surveillance.     

Ultrastructural characterization of the retrovirus particles (Sm-MTV) liberated from the mammary tumor cell line (Sm-MT) of a house musk shrew, Suncus murinus (Insectivora)

Detailed ultrastructure of a new type of retrovirus (Sm-MTV) released by cultured cells (Sm-MT) of a spontaneous mammary tumor from a house musk shrew Suncus murinus, Insectivora, is described. The virus particles were revealed as three forms: intracellular; budding; and extracellular. The intracellular type A particles were similar in profile to those associated with mouse mammary tumor cells and tended to form a small cluster of several particles in the cytoplasm. In addition, horseshoe-shaped particles as well as smaller particles in clusters, with doughnut-shaped morphology similar in structure to type A particles, were identified near the clusters of type A particles, although in smaller numbers. The budding particles contained a doughnut-shaped nucleoid, although the nucleoids decreased in size as compared with intracytoplasmic type A particles. The extracellular virions consisted of an envelope and a centrally located nucleoid. In routinely fixed specimens, the former was covered with irregularly distributed fuzzy materials in its surface, and the latter was further composed of a small electron dense core surrounded by an intermediate layer. Tannic acid treatment of cells resulted in the visualization of surface projections on the envelope of virions. Similar projections were also detected exclusively on the plasma membrane where virus budding took place, and not on the normal plasma membrane. The presence of surface projections on the viral envelope was further confirmed by the whole-cell-mounting technique. Together with our previous results of biochemical and immunological investigations, we concluded that Sm-MTV seemed to have closer phylogenetic relatedness with type D viruses of primates than with murine mammary tumor virus.     

Spontaneous lymphomas in SJL/J-(v+) mice: ecotropic and dualtropic virus expression in normal and lymphomatous tissues

Approximately 60% of inbred SJL/J-(v+) adult mice having high levels of ecotropic endogenous XC+ virus showed virus activation within the first month of life, while the others produced virus at comparable levels later on, in an attempt to correlate the time of virus activation with the incidence and latency of lymphomas, the tails of 57 1- and 2-month-old mice were tested for virus presence, and the mice were then observed for lymphoma appearance. While all 2-month-old mice expressed ecotropic virus, only 63% of the 1-month-old mice were virus-positive. However no relationship existed between early virus production (within 1 month) or late virus production and lymphoma latency, total lymphoma incidence, and histopathology. In contrast with high titers of XC+ virus in tail tissues of diseased mice, a markedly low virus content was found in lymphomatous organs. This difference was not due to selective growth of poor virus-producer cells or to inhibitory factors possibly released by the inflammatory cell component. Viral protein content and XC+ virus titer were not closely correlated in the neoplastic organs. Search for XC- viruses revealed that only 1 of 6 aged normal and 16 of 19 lymphomatous mice produced viruses that grew on mink lung cells. By use of a standard limiting dilution cloning procedure, four isolates were obtained that showed tropism for both murine and heterologous cells. Three of these isolates induced cytopathic changes similar to those induced by MCF viruses on mink lung cells but not on mouse cells. Interference and neutralization assays performed to better characterize the virus envelope properties further indicated that SJL/J isolates had features typical of MCF dualtropic viruses.