Detection of hepatitis A virus by extraction of viral RNA and molecular hybridization. (73/194)

Hepatitis A virus (HAV) RNA was extracted from cell culture, serum, liver, and feces and then detected by molecular hybridization with cloned HAV cDNA. Hybridization was approximately 10-fold more sensitive than immune electron microscopy or radioimmunoassay was and less sensitive than was assays of HAV infectivity in primates or in cell culture. As little as 10(3) 50% infective doses of HAV, or approximately 0.1 pg of viral RNA, was detected by this method. Analysis of fecal specimens from an experimentally infected marmoset and an epidemic of hepatitis A showed that HAV excretion could often be detected later in the illness by hybridization than by radioimmunoassay. This technique should be widely applicable for detection and analysis of HAV RNA.  (+info)

In vitro immortalization of marmoset cells with three subgroups of herpesvirus saimiri. (74/194)

Sequences within the rightmost 7 kilobases of the unique L DNA of herpesvirus saimiri are required for oncogenicity of the virus. The same DNA region has been found to be highly variable among different strains of herpesvirus saimiri. On the basis of this variability, herpesvirus saimiri strains were classified into groups A, B, and non-A, non-B. Herpesvirus saimiri strains representing the three groups were used successfully for in vitro immortalization of phytohemagglutinin-activated, interleukin 2 (IL-2)-expanded peripheral blood lymphocytes of common marmosets (Callithrix jacchus). Peripheral blood leukocytes could be immortalized from only a subset of common marmosets (5 of 13). All of the immortalized cell lines contained covalently closed circular viral DNA molecules and initially showed a low level of virus production. Cells immortalized by group A and group non-A, non-B strains did not require IL-2 in the medium. However, the only group B immortalized cell line, 473-SMHI, did not grow well in the absence of IL-2. The different characteristics of cell lines immortalized by herpesvirus saimiri strains belonging to different groups may help to elucidate some functions coded by the highly variable DNA region which is involved in the oncogenic process.  (+info)

A monoclonal antibody to glycoprotein gp85 inhibits fusion but not attachment of Epstein-Barr virus. (75/194)

Epstein-Barr virus (EBV) codes for at least three glycoproteins, gp350, gp220, and gp85. The two largest glycoproteins are thought to be involved in the attachment of the virus to its receptor on B cells, but despite the fact that gp85 induces neutralizing antibody, no function has been attributed to it. As an indirect approach to understanding the role of gp85 in the initiation of infection, we determined the point at which a neutralizing, monoclonal antibody that reacted with the glycoprotein interfered with virus replication. The antibody had no effect on virus binding. To examine the effect of the antibody on later stages of infection, the fusion assay of Hoekstra and colleagues (D. Hoekstra, T. de Boer, K. Klappe, and J. Wilshaut, Biochemistry 23:5675-5681, 1984) was adapted for use with EBV. The virus was labeled with a fluorescent amphiphile that was self-quenched at the high concentration obtained in the virus membrane. When the virus and cell membrane fused, there was a measurable relief of self-quenching that could be monitored kinetically. Labeling had no effect on virus binding or infectivity. The assay could be used to monitor virus fusion with lymphoblastoid lines or normal B cells, and its validity was confirmed by the use of fixed cells and the Molt 4 cell line, which binds but does not internalize the virus. The monoclonal antibody to gp85 that neutralized virus infectivity, but not a second nonneutralizing antibody to the same molecule, inhibited the relief of self-quenching in a dose-dependent manner. This finding suggests that gp85 may play an active role in the fusion of EBV with B-cell membranes.  (+info)

Peripheral nerve repair using muscle autografts. Recovery of transmission in primates. (76/194)

Skeletal muscle grafts, when thawed after freezing, can be used to repair peripheral nerves. This method was used after transection of the median nerve in the upper arm in marmosets. Examination at 28 days showed total denervation of flexor carpi radialis; at 150 days electrophysiological evidence of recovery of nerve conduction across the graft and of muscle activation was seen. Sections at this time showed nerve fibres and new functional neuromuscular junctions in the muscle. It is concluded that effective reinnervation of target muscles is possible after peripheral nerve repair using skeletal muscle autografts.  (+info)

Demonstration in vitro of cell mediated immunity to Epstein-Barr virus in cotton-top tamarins. (77/194)

In the course of developing an effective Epstein-Barr (EB) virus vaccine, the immune responses in cotton-top tamarins to a tumourigenic dose of EB virus were studied. Cell mediated responses were measured using a tissue culture 'growth inhibition' assay where peripheral blood lymphocytes were tested for their ability to inhibit the outgrowth of autologous EB virus transformed lymphoblastoid cells. This system has previously been recognized as a very sensitive assay for detecting cell-mediated responses to EB virus in man. Using this assay no cell-mediated immunity was detected up to the time of death in two tamarins following injection with a tumourigenic dose of EB virus. However, two other animals which had recovered from tumours induced by a first dose of EB virus 18 months previously when subsequently re-stimulated with a second tumourigenic dose did exhibit cell-mediated responses. These latter animals remained healthy following the re-challenge and did not show evidence of EB virus-induced disease.  (+info)

The potential anxiolytic activity of GR38032F, a 5-HT3-receptor antagonist. (78/194)

1. The highly selective 5-HT3-receptor antagonist, GR38032F, has been tested in five animal models predictive for anxiolytic activity. 2. In the social interaction test in the rat and in a light/dark exploration test in the mouse, GR38032F dose-dependently released suppressed behaviour without modifying locomotor activity. 3. In the cynomolgus monkey and the marmoset, GR38032F reduced anxiety-related symptoms without causing sedation. In the marmoset, the effects were clearly dose-related. 4. GR38032F did not have any detectable activity in the water-lick conflict test in the rat. 5. We conclude that GR38032F is potentially a very potent anxiolytic agent without sedative, anticonvulsant or hypnotic activity.  (+info)

A primate species with limited major histocompatibility complex class I polymorphism. (79/194)

Extensive polymorphism at the major histo-compatibility complex (MHC) is thought to confer immune protection on populations. A New World primate, the cotton-top tamarin (Saguinus oedipus), has a high prevalence of ulcerative colitis and adenocarcinoma of the colon and dies after infection with several human viruses. Lymphocytes from all animals tested expressed on common MHC class I allelic product. Another MHC class I allelic product was expressed by 39 of 41 tested animals. Four other allelic products were also expressed on the lymphocytes of these animals at a frequency of greater than 50%. MHC class II gene products, however, were polymorphic. Restriction fragment length polymorphism analysis confirmed that there were a limited number of cotton-top tamarin MHC class I alleles, whereas the MHC class II gene loci were polymorphic. This sharing of MHC class I alleles is unprecedented in a higher primate species and may play a role in the susceptibility of this endangered species to pathogens.  (+info)

Effects of the 5-HT3 receptor antagonist, GR38032F, on raised dopaminergic activity in the mesolimbic system of the rat and marmoset brain. (80/194)

1 The ability of the selective 5-HT3 receptor antagonist GR38032F to reduce raised mesolimbic dopaminergic activity was studied in behavioural experiments in the rat and marmoset. 2 GR38032F injected into the nucleus accumbens (0.01-1 ng) or peripherally (0.01-1 mg kg-1 i.p.) inhibited the locomotor hyperactivity caused by the acute intra-accumbens injection of amphetamine (10 micrograms) in the rat. Similar treatments with sulpiride and fluphenazine also inhibited the amphetamine-induced hyperactivity. 3 The peripheral administration of GR38032F (0.001-0.1 mg kg-1 i.p., b.d.) during a 13 day period of dopamine infusion (25 micrograms 24 h-1) into the nucleus accumbens of the rat reduced the dopamine-induced hyperactivity response to control (vehicle infused) levels. Locomotor activity remained at control levels after discontinuing the dopamine/GR38032F treatment regimen. 4 The hyperactivity caused by the infusion of dopamine into the rat nucleus accumbens was also inhibited by fluphenazine (0.01-0.05 mg kg-1 i.p., b.d.), but locomotor activity was suppressed to levels below control values and a rebound hyperactivity occurred after discontinuation of the dopamine/fluphenazine treatment regimen. 5 The discontinuation of a concomitant 13 day intra-accumbens infusion of dopamine with haloperidol, 0.01 mg kg-1 i.p.t.d.s., caused a rebound hyperactivity. This hyperactivity was suppressed by GR38032F (0.001-0.1 mg kg-1 i.p.). 6 The unilateral infusion of dopamine (25 micrograms 24 h-1, 13 days) into the left amygdala of rats having right hemispheric dominance (as measured in a turn preference test) caused locomotor hyperactivity. Intraperitoneal administration of GR38032F (0.1-100 micrograms kg-1) or fluphenazine (0.025-0.1 mg kg-1), and the intra-amygdaloid injection of GR38032F (0.1-100 ng) or fluphenazine (25-500 pg), either into the infused or non-infused side, inhibited the dopamine-induced locomotor hyperactivity. 7 Marmosets receiving bilaterial infusions of dopamine (25 micrograms 24 h-1 for 13 days) into the nucleus accumbens also exhibited increased locomotor activity, GR38032F (0.1-1.0 micrograms kg-1 t.d.s.), reduced the hyperactivity to control levels with no rebound hyperactivity following the discontinuation of the dopamine/GR38032F treatment regimen. Fluphenazine (0.01-2.5 mg kg-1 i.p., t.d.s.) also inhibited the hyperactivity, but locomotor activity was reduced to values below control levels and a rebound hyperactivity followed the discontinuation of the dopamine/fluphenazine treatment. 8. It is concluded that the 5-HT3 receptor antagonist GR38032F, and the neuroleptic agents fluphenazine, sulpiride and haloperidol, can reduce raised mesolimbic dopaminergic activity in the rat and marmoset. GR38032F is distinguished from the dopamine receptor antagonists by, firstly, its ability to return the hyperactivity response to control values, without excessive suppression of locomotion even on enhanced dosage regimes and, secondly, by the lack of rebound hyperactivity following abrupt discontinuation of its treatment.  (+info)