Evaluation of three commercial screening tests for AIDS virus antibodies

Three commercial enzyme-linked immunosorbent assays (ELISA) for acquired immune deficiency syndrome (AIDS) virus antibodies were evaluated using serum that had been characterized by an ELISA and western blot procedure developed at the University of California at Davis (UCD). Each of the commercial tests was more specific than the UCD ELISA, but the UCD ELISA was more sensitive in the detection of sera that lacked reactivity by western blot to the envelope glycoprotein (gp-41). The HTLV-III Bio-EnzaBead (Litton Bionetics, Charleston, SC) was less sensitive and specific than the Abbott HTLV-III EIA (Abbott Laboratories, North Chicago, IL) or the Virgo HTLV-III ELISA (Electro-Nucleonics Inc., Columbia, MD). Overall, 22.9% (57 of 250) and 51.0% of sera that were repeatedly (X2) positive by commercial screening kits tested at blood donor centers and clinical laboratories, respectively, were confirmed by western blot. These results indicate that the screening assays for AIDS virus antibodies are not equal in performance and that positive screening test results must be confirmed by a more specific test like western blot before results are released.

Transfer, by selective breeding, of the pathogenic Mtv-2 endogenous provirus from the GR strain to a wild mouse line free of endogenous and exogenous mouse mammary tumor virus

The GR laboratory mouse strain has five endogenous proviral copies of the mouse mammary tumor virus (MMTV). One of these, Mtv-2, is unique because it causes mammary carcinomas in virtually 100% of breeding GR females prior to 1 year of age. To facilitate studies of this locus in particular, and mammary tumorigenesis in general, we genetically tailored a new mouse line, WXG-2, which bears Mtv-2 as its only endogenous MMTV provirus. The WXG-2 line was constructed by making hybrids between the GR strain and a wild mouse line free of both endogenous and exogenous MMTV, backcrossing to the MMTV-free line, and fixing the Mtv-2 locus in a population with the desired genotype. Mammary tumors were observed in 5 of the 20 hybrid females carrying the endogenous Mtv-2 provirus. The WXG-2 line represents a new model system for studying MMTV-induced mammary tumorigenesis in the absence of multiple endogenous proviruses.

Distribution of type D retrovirus sequences in tissues of macaques with simian acquired immune deficiency and retroperitoneal fibromatosis

Horizontally acquired SAIDS retrovirus type 2 (SRV-2), a type D retrovirus related to the Mason-Pfizer monkey virus, has been associated with the simian acquired immunodeficiency syndrome (SAIDS) including retroperitoneal fibromatosis (RF) in several macaque species at two primate research centers. Virus specific gene sequences are present in lymphoid and RF tissues but not in muscle tissue of diseased macaques or in any tissues of uninfected normal monkeys. Serologic and restriction endonuclease mapping techniques have defined unique SRV-2 strains in the Celebes (SRV-2C) and rhesus (SRV-2R) macaques at the Oregon Regional Primate Center, SRV-2 is related to both MPMV and SAIDS type 1 retroviruses and it has no detectable molecular homology with the human AIDS retroviruses.

Human alpha- and beta-interferon but not gamma- suppress the in vitro replication of LAV, HTLV-III, and ARV-2

The effect of human interferons (IFNs) (alpha, beta, and gamma) on the in vitro replication of AIDS viruses (LAV, HTLV-III, and ARV-2) in human peripheral blood lymphocytes was investigated. At the time of peak virus production, IFN-alpha preparations (leukocyte, Namalwa, alpha 1, and alpha 2) at 100 U/ml, suppressed LAV, HTLV-III, and ARV-2 replication as measured by reverse transcriptase (RT) activity by greater than 50%. This suppression was dose dependent and high dosages (500 U/ml) of IFN-alpha resulted in almost complete suppression of RT activities (77-99%). A low dose (100 U/ml) of IFN-beta suppressed all three AIDS viruses by 75%. In contrast, human IFN-gamma at a dose range from 100 U/ml to 500 U/ml had no significant effect on the production of infectious viruses. These results indicate that only IFN-alpha and -beta are effective against LAV, HTLV-III, and ARV-2 replication. A continuous supply of IFN appeared to be essential for the constant suppression of RT activity. In fact, upon termination of single IFN treatment, enhanced virus production resulted.

Nucleotide sequence of SRV-1, a type D simian acquired immune deficiency syndrome retrovirus

Simian acquired immune deficiency syndrome (SAIDS) in the macaque genus of monkeys at the California Primate Research Center is apparently caused by infection by a type D retrovirus. The complete nucleotide sequence (8173 base pairs) of a molecular clone of the prototype SAIDS virus isolate, SRV-1, reveals a typical retrovirus structure with long terminal repeats (346 base pairs) and open reading frames for the gag (663 codons), pol (867 codons), and env (605 codons) genes. SRV-1 also has a separate open reading frame of 314 codons between the gag and pol genes that defines the viral protease gene (prt) and a short open reading frame of unknown significance downstream from the env gene. The SRV-1 protease region shows a high degree of homology to its counterpart in the hamster intracisternal A-type particle genome; both these protease genes are about twice as long as the analogous region of other retroviruses. SRV-1 has no notable similarity in either genetic organization or sequence to the human AIDS retroviruses.

Recombinant DNA approaches to feline leukemia virus immunization

We have utilized 2 recombinant DNA strategies for immunization against FeLV in cats: (a) modified live virus was attenuated by mutation and recombination, and (b) an immunogen, consisting of subunit envelope protein, was prepared in genetically engineered yeast. Results indicated that the genetically manipulated live virus preparations were not protective against FeLV challenge because they were either not attenuated in virulence or were not sufficiently antigenic. Immunization with yeast-synthesized FeLV envelope protein followed by the modified live virus gave protective immunity in cats under experimental conditions. Future immunization attempts will concentrate on enhancing the immunogenic potency of the yeast- synthesized FeLV envelope protein.

Monocyte function in rhesus monkeys with simian acquired immune deficiency syndrome

Monocyte function in rhesus monkeys with simian acquired immune deficiency syndrome (SAIDS) was compared with that in age-matched normal juvenile rhesus monkeys. The functional tests were 1) chemotaxis, 2) phagocytosis of opsonized Candida albicans, 3) killing and/or growth inhibition of Candida albicans, 4) generation of respiratory burst, and 5) monocyte-derived macrophage response (morphology and/or respiratory burst) to stimulating agents such as lymphokines, gamma interferon, endotoxin, and phorbol myristate acetate. The monkeys tested had either clinical SAIDS (alive with lymphadenopathy, splenomegaly, and lymphopenia or neutropenia) or had terminal SAIDS (moribund due to the disease). Responses of monocytes from 14 monkeys with clinical SAIDS were indistinguishable from those of 9 normal juvenile rhesus monkeys, whereas monocytes from 3 monkeys with terminal SAIDS had enhanced phagocytosis and respiratory burst capacity. Chemotaxis, candidacidal/stasis activity, and response to stimulating agents were normal in these terminal cases. Plasma from the SAIDS monkeys was as capable of opsonizing yeasts and of being able to generate chemotactic factors by endotoxin as was control plasma. SAIDS retrovirus (SRV) was detected by co-cultivation of pure monocyte-derived macrophage cultures with Raji cells, an indicator cell line which forms syncytia in the presence of SRV. Four terminal SAIDS cases and one late-stage clinical SAIDS case were virus-positive when the number of macrophages in the cultures ranged from less than 50 to about 500. Terminal SAIDS monocyte-derived macrophages in culture as long as 17 days produced SRV. These data show that in monkeys with SAIDS the major effector functions of monocytes and macrophages involved in host defense are intact (even up until death). Additionally, some of the monocytes are productively infected, and these infected monocytes are viable and adherent in culture.

Ultrastructural comparison of the retroviruses associated with human and simian acquired immunodeficiency syndromes

Three isolates of human acquired immunodeficiency syndrome (AIDS) virus (lymphadenopathy-associated virus, human T cell lymphotropic virus strain III, acquired immunodeficiency syndrome-associated retrovirus) were compared with simian AIDS virus by thin section transmission electron microscopy. Simian AIDS virus was found to form intracytoplasmic A particles and to bud by both ring forms and crescent shapes. The extracellular mature simian AIDS virus exhibited a cylindrical nucleoid within a tubular or conical core shell. The simian AIDS virus was morphologically indistinguishable from Mason-Pfizer monkey virus, the prototype D type retrovirus, although the two were readily distinguished by radioimmunoassay and restriction endonuclease mapping. All three AIDS virus isolates exhibited identical ultrastructure and maturation sequences. The AIDS viruses did not form intracytoplasmic A particles and budded only with crescent-shaped nucleoids. Mature extracellular AIDS viruses contained an eccentric spherical nucleoid within a conical or tubular core shell. AIDS virus was found to show many morphologic features of the retroviral subfamily Lentivirinae. The AIDS virus isolates appear to form a new group of retroviruses.

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.

Molecular comparison of retroviruses associated with human and simian AIDS

Infectious retrovirus(es) associated with the human (LAV, HTLV-III, ARV) and simian (SAIDS-1) acquired immune deficiency syndrome were compared by electron microscopy, immunofluorescence and immunoblotting techniques and by restriction endonuclease mapping of the viral genomes. The extracellular virus particles had similar type D morphology, but intracytoplasmic type A nucleoids were found only in SAIDS virus infected cells. Although the antigens of the three prototype AIDS viruses were similar, no cross-reactivity with the SAIDS virus was detected. Molecular hybridization and restriction enzyme analysis also revealed that the SAIDS and AIDS viruses were genetically unrelated. However, only minor differences, consistent with strain polymorphism, were found between the three AIDS virus isolates. Thus, the retroviruses associated with AIDS in macaques and humans are unique to each species.

AIDS serology testing in low- and high-risk groups

The performance characteristics of the acquired immunodeficiency syndrome (AIDS)-retrovirus serological tests including enzyme-linked immunosorbent assay (ELISA), Western blot, and immunofluorescence assay were defined in a clinical laboratory setting by testing 1,257 serum specimens from low- and high-risk groups for AIDS. The three prototype AIDS retroviruses (lymphadenopathy-associated virus, human T-lymphotropic virus III, and AIDS-associated retrovirus) were equally suitable as target antigen for these assays. Sera from six of 74 laboratory and health care personnel and 91 of 1,014 unselected blood donors were falsely positive by ELISA (positive to negative ratio [P/N], greater than or equal to 2) based on the lack of Western blot confirmation. Only two true-positives (two [0.2%] of 1,014 blood donors) were detected in these low-risk groups. In contrast, 106 of 108 specimens with ELISA P/N ratios of 2 or greater from the high-risk groups including asymptomatic homosexual men, hemophiliacs, AIDS-related complex patients, and AIDS patients were positive by Western blot and immunofluorescence assay. Four false-negative ELISA results based on positive immunofluorescence assay and Western blot were found in the AIDS patient group. Ten of 69 AIDS patients were negative by all three serological tests. The consequence of maintaining high sensitivity for the ELISA (P/N ratio, greater than or equal to 2) as a screening test was a loss of specificity. The number of false-positive results necessitated the use of a confirmation test with greater specificity.

Immune defects in simian acquired immunodeficiency syndrome

We recently reported a Simian Acquired Immunodeficiency Syndrome (SAIDS) in rhesus macaques at the California Primate Research Center. Here, we studied in vitro lymphocyte response to the mitogens Concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) with and without interleukin 2 (IL-2). Immunoglobulin (IgG and IgM) and complement (C3 and C4) concentrations were determined by radial immunodiffusion. T helper and T suppressor lymphocytes were identified with the monoclonal antibodies OKT4 and OKT8. Concentrations of IgG and IgM were significantly (p less than .05) decreased. Complement component C3 did not change but C4 was increased. The absolute lymphocyte count decreased but the OKT4:OKT8 ratio was unchanged from controls. A decreased lymphocyte response to all mitogens occurred early and became more severely depressed near death. IL-2 caused a complete or partial restoration of the response to the mitogens CON A and PHA. Both the humoral and cell mediated immune responses are affected in SAIDS. The role of IL-2 in this immune defect must be studied further.

Myxoid chondrosarcoma with a translocation involving chromosomes 9 and 22

Myxoid chondrosarcoma is an uncommon neoplasm thought to be derived from mesenchymal chondrocytic cells. Although cytogenetic abnormalities have been reported in sarcomas, too few cases have been studied to determine the frequency of nonrandom chromosomal changes in mesenchymal tumors. In this article, we describe a chondrosarcoma with a nonrandom reciprocal translocation t(9;22)(q22;q11). The cellular homologue to the retrovirus transforming gene of simian sarcoma virus is located on chromosome #22, and its possible significance in this case is discussed.

Retroviral spongiform polioencephalomyelopathy

Aging wild mice (Mus musculus domesticus) from several different trapping areas in southern California are uniquely prone to a naturally occurring hind-leg paralytic disease and/or lymphoma. Both conditions are caused by an indigenous ecotropic murine leukemia virus (MuLV). These mice have a lifelong persistent viremia with total immunologic tolerance to the virus. The characteristic pathologic features are centered on the anterior-lateral horns of the lumbosacral spinal cord and consist primarily of a noninflammatory spongiform change, with reactive gliosis and neuronal dropout. The main cause of neuronal death apparently is abortive intracytoplasmic replication of virus particles. Genetic control of the naturally occurring disease in wild mice is achieved by segregation of a dominant ecotropic virus restriction gene, Akvr-1R/Fv-4R. The neurologic and/or neoplastic diseases are readily reproduced by experimental inoculation of newborn susceptible laboratory mice with purified, cloned ecotropic virus derived from the affected wild mice. The biologic and pathologic features of the experimental paralysis closely resemble those of the natural disease. This nononcogenic retroviral disease is useful in understanding the molecular basis of direct, virus-induced, neuronal and glial cell degeneration and their sequelae.

Hyperplastic and neoplastic changes in the mammary glands of feral mice free of endogenous mouse mammary tumor virus provirus

Laboratory colonies of feral mice (Mus musculus domesticus) have been established with specific mouse mammary tumor virus (MuMTV) genotype, including colonies lacking any proviral DNA (ev-) or carrying only a single copy of MuMTV DNA (ev+). No evidence of a decline in reproductive capacity has been observed in the first 8 generations. Both the ev- and ev+ mice showed normal mammary gland development and the development of hyperplastic lesions in the older females. The mice were very resistant to spontaneous or chemically induced mammary tumors. However, the occurrence of 1 mammary tumor in an ev- mouse indicates that mammary neoplasias can occur in the absence of MuMTV DNA. The few tumors that do occur in the ev- mice provide a unique opportunity to study the neoplastic process in the absence of proviral DNA.

Isolation of a feline leukaemia provirus containing the oncogene myc from a feline lymphosarcoma

The molecular mechanism by which feline leukaemia virus (FeLV) induces lymphoid malignancy in domestic cats is largely unknown. Using the insertional activation model of c-myc by avian leukosis virus in the induction of bursal lymphoma in chickens, we have now characterized the c-myc locus in feline tissues and investigated the possibility that FeLV may also insert within feline c-myc. We used the 1.5 kilobase (kb) PstI fragment of MC29 v-myc in Southern blot analysis to characterize the structure of the c-myc locus in the DNA of 31 naturally occurring feline lymphomas. Analysis of a cloned c-myc gene from one lymphoma demonstrated that sequences homologous to v-myc occupy 2.6 kb of feline DNA in which a putative intron of 0.5 kb separates sequences homologous to the 5' and 3' exons represented in avian v-myc. We also observed in the DNA of this lymphoma tumour-specific fragments homologous to v-myc. Characterization of these molecularly cloned myc-hybridizing fragments revealed the presence of at least two identical FeLV proviruses 5.5 kb in length, each containing long terminal repeats enclosing a spliced version of the feline myc gene.

Clinical features of simian acquired immunodeficiency syndrome (SAIDS) in rhesus monkeys

A syndrome of acquired immunodeficiency has been identified in a group of rhesus monkeys (Macaca mulatta) which died at the California Primate Research Center. Clinical evaluation of these animals revealed that 50% or more had lymphadenopathy, weight loss, and diarrhea. At least 30% had splenomegaly, fever, cutaneous abscesses and/or arthritis/myositis. Two animals had fibrosarcomas. Anemia was seen in 19 animals, lymphopenia in 14, granulocytopenia in four and thrombocytopenia in three. Hepatitis was diagnosed histopathologically in 13. Electrophoresis revealed hypoproteinemia, hypoalbuminemia and hypogammaglobulinemia. Numerous bacterial, protozoal, and viral agents were identified including cytomegalovirus and leukocyte-associated herpesvirus. Pathologic lesions included severe post-reactive depletion of lymphocytes in germinal centers and paracortical regions of lymph nodes. Clinical and pathologic changes indicate an acquired immunodeficiency syndrome which has some similarities to AIDS in humans. This disease in monkeys may provide a model for studying that disease.

Epidemiologic aspects of an outbreak of acquired immunodeficiency in rhesus monkeys (Macaca mulatta)

Since August 25, 1981, an outbreak of simian acquired immunodeficiency syndrome ( SAIDS ) has been recognized in a single outdoor corral housing 77 rhesus monkeys (Macaca mulatta) over a 16-month period. The etiology of this syndrome is unknown but epidemiologic evidence suggests an infectious agent. Thirty-two cases of SAIDS have been identified (31 female, 1 male), and 27 of these animals have died (case fatality rate = 84%). Three of these deaths occurred among 13 infants born in the corral . All 27 deaths were females. For animals in the original cohort, sex was not a statistically significant risk factor. For animals born in the corral females were at greater risk (p = 0.0489; Fisher's Exact Test). SAIDS mortality rates were highest for animals entering the corral at less than 30 months of age (4.4 deaths per 100 monkey months of follow-up) and for animals born into the cage (3.3 deaths per 100 monkey-months of follow-up). The mortality rate was lowest for animals entering the corral at greater than 30 months of age, (0.32 deaths per 100 monkey-months of follow-up). No significant associations were found for the factors weaning history, cage-move history, parentage, generation, and medical history, including history of bite-wound trauma. Nine of the original 64 animals entering the corral on August 25, 1981, were previously associated with a group of 110 rhesus monkeys occupying this same corral from September 1976 to August 1981. Though less dramatic, a similar pattern of morbidity and high mortality was recognized retrospectively in this group.(ABSTRACT TRUNCATED AT 250 WORDS)

The pathology of an epizootic of acquired immunodeficiency in rhesus macaques

A syndrome of acquired immunodeficiency within a group of outdoor-housed rhesus macaques (Macaca mulatta) with unusually high mortality has been identified at the California Primate Research Center. The cause of death for most of the affected animals included septicemia and/or chronic diarrhea with wasting, often complicated by other problems. In many cases, multiple or unusual infectious agents were isolated or recognized, including cytomegalovirus, Cryptosporidium spp., and Candida albicans. Septicemias due to usually innocuous agents such as Staphylococcus epidermidis and Alcaligenes faecalis were seen. Two animals developed cutaneous fibrosarcomas. Affected animals had generalized lymphadenopathy and splenomegaly, with depletion of T-cell populations, initially follicular hyperplasia followed by depletion, and absence of plasma cells. This spontaneous disease syndrome in nonhuman primates has similarities to acquired immune deficiency syndrome (AIDS) in humans, providing an animal model for the study of the complex factors modulating the immune system.

Isolation and characterization of new ecotropic murine leukemia viruses after passage of an amphotropic virus in NIH Swiss mice

Amphotropic murine leukemia viruses (MuLV-A) cause mainly lymphoma in newborn inoculated NIH Swiss mice after a long latent period of 6-12 months. Rarely, however, about 1% of the inoculated mice develop hind limb paralysis and progressive central nervous system disease. The biological properties and RNase T1-resistant oligonucleotide fingerprints of the recovered viruses from tissues of both lymphomatous and paralyzed mice inoculated with MuLV-A were analyzed. These results indicate that serial in vivo passages of MuLV-A in NIH Swiss mice lead to generation of new MuLVs of both amphotropic and ecotropic host ranges. The recovered amphotropic viruses are highly lymphomagenic and are recombinants of MuLV-A-specific oligonucleotides and endogenous mouse sequences. The ecotropic viruses fall into two groups: (1) recombinants of MuLV-A genes and NIH Swiss mouse viral or cellular sequences and (2) new ecotropic viruses with oligonucleotide fingerprints not related to any of the known MuLVs. The naturally occurring ecotropic MuLVs of the wild mice produce both lymphoma and paralysis in NIH Swiss mice. The viruses recovered from in vivo passages are mainly of ecotropic host range although dual-tropic virus activity is occasionally seen in the spleens but not in the brains or spinal cords of the lymphomatous or paralyzed mice. Oligonucleotide fingerprinting of the recovered MuLV-Es from paralyzed mice are identical to the input MuLV-Es, indicating that the parental MuLV-E alone, without recombination, is responsible for the paralytic disease.