Genetic variation of bovine leukemia virus (BLV) after replication in cell culture and experimental animals.

This article reports the selection of bovine leukemia virus (BLV) variants after continuous passage in cell lines or experimental animals. Two wild BLV strains isolated from 2 naturally infected Holstein dairy cows in Brazil (cow codes: 485 and 141) were used for the experimental infection of 1 sheep and FLK cells, and 1 rabbit and CC81 cells. Viral DNA was isolated several months after infection, and env gene nucleotide and amino acid sequences of the "passaged" variants were compared against the 2 original infecting wild strains. The sequences of the original infecting wild strains were not recovered after their replication in the cell lines or experimental animals. These results indicate that genetic variation occurred after BLV replication in vivo and in vitro, with new variants being selected.

Vírus da artrite encefalite caprina: isolamento e caracterização de parte do gene gag / Caprine arthritis-encephalitis virus: isolation and molecular characterization of part of the gag gene

Amostras de sangue de 12 animais soropositivos pelo teste de imunodifusão em gel de agarose e que não apresentavam sinais clínicos sugestivos de infecção pelo vírus da artrite-encefalite caprina (CAEV) foram coletadas para isolamento viral. Mácrofagos derivados de monócitos foram co-cultivados com células de membrana sinovial caprina (MSC), resultando em cinco amostras que apresentaram efeito citopático característico do tipo persistente, semelhante ao observado para o CAEV. Uma técnica de reação em cadeia de polimerase (PCR) foi padronizada para amplificar parte do gene gag do genoma pró-viral, codificante para a proteína do capsídeo viral (p25). As cinco amostras foram amplificadas pela PCR e três delas, BR-UFMG/PL1, BR-UFMG/PL2 e BR-UFMG/PL3, foram seqüenciadas diretamente dos seus produtos de PCR. O alinhamento múltiplo das seqüências obtidas com outras de lentivírus de pequenos ruminantes (LVPR), obtidas no GenBank, e o dendrograma revelaram que as novas amostras de CAEV são únicas e distintas das demais amostras de LVPR, possuindo maior identidade de nucleotídeos e aminoácidos entre si e com as amostras de CAEV do que com a do vírus maedi-visna.

Partial sequencing of env gene of bovine leukaemia virus from Brazilian samples and phylogenetic analysis.

Analysis of the partial bovine leukaemia virus (BLV) env gp51 gene sequences obtained from three BLV strains isolated in three different regions of Brazil was carried out. The Brazilian BLV env gp51 sequences were compared with seven other corresponding sequences of BLV strains isolated in different countries and with consensus sequence as well. The obtained data point on qualitative and quantitative differences among the analysed strains as far as the occurrence of single point mutations is concerned. Two Brazilian strains show significantly higher mutation rate than other analysed strains. Amino acid analysis did not show, however, any substantial changes of the primary protein structure coded by well conserved region of BLV env gp51 gene. Based on the obtained data, the putative dendogram image of possible phylogenetic relations among the studied BLV strains is presented as well.

Significance of anti-interferon-alpha2 and sICAM-1 activities in the sera of viral hepatitis B and C patients treated with human recombinant interferon-alpha2.

In this study the presence of an IFN-binding activity in the sera of patients with chronic viral hepatitis B or C treated with rIFN-alpha2 was screened by a radioimmune assay (RIA) using radiolabeled rIFN-alpha2. Incidence of an anti-IFN activitywas compared with hepatitis B virus (HBV) or hepatitis C virus (HCV) serum markers as hepatitis B s antigen (HBsAg), hepatitis B e antigen (HBeAg), antibodies to HBsAg (anti-HBsAg), antibodies to HBeAg (anti-HBeAg), seroconversion, HBV DNA, HCV RNA, and serum soluble intracellular adhesion molecule I (sICAM). Injections (intramuscular) of rIFN-alpha2 caused an anti-rIFN activity formation in 8 (27.6%) of 29 patients with chronic active hepatitis B (CAH-B) and in 8 (30.8%) of 26 patients with chronic active hepatitis C (CAH-C). The presence of the anti-rIFN activity in CAH-B patients correlated frequently with the persistence of HBsAg, HBeAg and HBV-DNA, while its absence was often accompanied by the anti-HBeAg and anti-HBsAg seroconversion, respectively, and HBV-DNA negativity. In two CAH-C patients who became HCV RNA-negative no anti-IFN activity was found. Levels of serum sICAM-1 in CAH-B patients responding to the IFN treatment were higher than those in non-responders or in which the anti-IFN activity was present. The anti-IFN activity may negatively influence the effect of the IFN therapy of CAH-B or CAH-C patients at early stages of the therapy. The appearance of the anti-IFN activity at the end of a long-term IFN therapy does not seem to influence the outcome of the therapy. sICAM-1 may be involved in the process of CAH-B reactivation and IFN-triggered cytotoxicity during the IFN therapy.

Therapy-induced antibodies to interferon-alpha 2a recognise its receptor-binding site.

Fifty-eight patients with chronic hepatitis B (HB) or C (HC) were treated with recombinant human interferon (rIFN)-alpha 2 and their sera were assayed for antibodies to rIFN-alpha 2c. Twelve of these patients produced low titres and two high titres of the antibodies. We localized the region which was recognised by the high-titre therapy-induced antibodies on the IFN molecule by testing the antibodies with a set of murine monoclonal antibodies (MoAbs) to IFN-alpha 2 in a competitive radioimmune assay (RIA). Only MoAbs with epitopes located in the amino-terminal portion of IFN-alpha 2 could inhibit the binding of radiolabelled IFN-alpha 2 by patients' sera. Our data indicate that the therapy-induced antibodies were directed to the receptor-binding domain of IFN-alpha 2 formed by amino acids (aa) 30-53. In accordance with this observation, human anti-IFN sera inhibited the binding of rIFN-alpha 2 to human cells.

Interferon-omega suppresses hepatitis B surface antigen production in human hepatoma cell line.

Biological activities of human interferon (IFN) omega are less well characterized than those of other type I human IFNs. We compared the ability of recombinant IFN-omega, IFN-alpha 2 and IFN-gamma to inhibit the production of viral hepatitis B surface antigen (HBsAg) in the human hepatoma cell line PLC/PRF/5. The results demonstrated that the capacity of IFN-omega to suppress the HBsAg synthesis was similar to that of IFN-alpha 2. The kinetics of the inhibitory effect of IFN-gamma differed from those of the two other IFNs.

Links between prolonged exposure to xenobiotics, increased incidence of hepatopathies, immunological disturbances and exacerbation of latent Epstein-Barr virus infections.

Disturbances of several humoral and cellular immune parameters are significantly increased in individuals exposed to chemical pollutants. Moreover, exacerbations of the latent Epstein-Barr virus (EBV) infection were more frequently observed in the chemically exposed group than in the control groups. A significant correlation was seen between EBV exacerbations and the increased number of eosinophils, T-lymphocyte rosette formation and the respiratory burst of polymorphonuclear blood cells. Possible links between hepatopathy due to xenobiotics exposition, immunological disturbances and EBV exacerbation are discussed, including a putative role of EBV-induced (autocrine) cytokines.

Effect of sera of cirrhotic patients with or without hepatitis B virus infection on protein synthesis in hepatoma cells.

The in vitro effects of sera of 11 patients with liver cirrhosis on protein synthesis in PLC/PRF/5 cells were studied. Hepatitis B virus (HBV) infection was documented in 7 patients. Increased random production of several cell proteins of M(r) of approximately 25, 65, 90 and 130 K was shown by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). There was no correlation between HBV-positive and HBV-negative cirrhosis and the induced proteins. One of them was identified as alpha-1 foetoprotein by immunoblot analysis. C-reactive protein (CRP) was determined only in one case; production of interleukin-6 (IL-6) was not detected.

Synthesis of 23 K acute-phase protein by HBV genome carrying PLC/PRF/5 human hepatoma cells.

Elevated synthesis of 23 K protein by human hepatoma PLC/PRF/5 cells was observed after their treatment with conditioned medium from concanavalin A stimulated peripheral-blood monocytes. Increased amount of this protein was first determined 4 hr after the treatment and its maximal level was reached 48 hr later. The role of the 23 K protein remains so far unknown.

[Prenatal virus infections and orofacial clefts]. / Prenatálne vírusové infekcie a orofaciálne rázstepy.

A potential teratogenic activity of virus infections caused by the viruses of rubella, influenza, parotitis, hepatitis B, cytomegalovirus and the Epstein-Barr virus was investigated. Specific antibodies against these viruses were examined serologically in children with orofacial clefts and in their mothers and the results were compared with those obtained in control children and their mothers. Different micromethods were used in performing the examinations (ELISA, RIA, NIR, KFR, HIT). Evaluation of the results and their statistical processing supports the assumption that prenatal infection may have occurred in the series studied induced by the viruses of influenza, rubella, cytomegalovirus, and possibly also by the Epstein-Barr virus. No association with the viruses of parotitis and hepatitis B was established. (Tab. 5, Ref. 36.)

Interferon-neutralizing or enhancing activities in hybridoma cell fluids after in vitro immunization.

Several hybridomas supernatants capable of interferon beta (IFN-beta) or "IFN epsilon" ("IFN-eps") neutralizing or enhancing activities were obtained after in vitro immunization of BALB/c and C57 mice spleen cells and their fusion with Sp2/0 plasmacytoma cells. Besides rather low anti-IFN-beta or "eps" antibody secretion several cloned hybridoma fluids contained a factor potentiating anti-viral activity of the both IFNs. It is speculated that this activity is due to production by some hybridomas of another lymphokine.

[Essential phospholipids in the treatment of chronic hepatitis B virus infection]. / Esenciálne fosfolipidy v liecbe chronickej infekcie vírusom hepatitidy B.

The authors investigated 24 patients with chronic infection with the hepatitis B virus. HBeAg-positive patients had significantly (alpha = 0.05) more frequently pathological initial values of biochemical and immunological indicators, as compared with anti-HBe-positive patients. Delta antigen in the liver and anti-delta antibodies in serum if examined, were always negative. All patients were subjected to 16-week treatment with Essentiale forte (Natterman). After treatment and after the subsequent 16 weeks in none of the patients loss of HBsAg or seroconversion of HBeAg-positive to anti-HBe-positive was recorded. In the sub-group of HBeAg-positive subjects after treatment a significant drop of gamma-globulins and circulating immunocomplexes occurred, in the sub-group of anti-HBe-positive subjects a significant rise of active and total T-lymphocytes was found. The authors recommend to test Essentiale forte in the prevention and treatment of immunocomplex disease in chronic infection with the hepatitis B virus.

Transient increase of HBsAg levels following human IFN alpha treatment signalises the patient's response in chronic active hepatitis B.

Eleven patients in early stages of chronic active hepatitis B (CAH-B) were treated for weeks or months with a natural or recombinant human interferon alpha (Hu IFN alpha). Changes of serum levels of selected hepatitis B virus (HBV) markers were observed after Hu IFN alpha administration. Increase of HBsAg level accompanied by more or less simultaneous HBeAg level depression was the most interesting observation. These changes were well expressed in 5 reactive patients only; they usually ceased after withdrawal of IFN therapy. Reaction of the remaining 6 patients was either poor or not demonstrable. The possible mechanism for HBsAg/HBeAg serum level changes during the IFN therapy of CAH-B is discussed.

Immunological markers in patients with different forms of viral hepatitis B treated by "conventional" therapy or with HuIFN alpha.

Selected immunological, biochemical, and other viral hepatitis B (VH-B) markers were followed and analysed during "conventional" or human interferon alpha (HuIFN alpha) therapy of patients with different forms of VH-B. The immunological data obtained from "conventionally"-treated acute hepatitis B (AH-B), prolonged acute hepatitis B (AH-BP) or chronic active hepatitis B (CAH-B) patients disclosed differences unsatisfactory for comparison of the influence of HuIFN alpha therapy on changes of the immunological markers. More valuable data were obtained through continuous registration of the dynamics of selected blood markers. Partial effects on immunological parameters were seen after HuIFN alpha administration to 2 patients with developing CAH-B infection. Progression of the disease was markedly halted in these both patients after IFN treatment.

Relationship between depression of HBsAg production and DNA synthesis by interferons in human hepatoma cell line.

The influence of different interferons (IFNs) on HBsAg production and DNA synthesis was studied in PLC/PRF/5 cells using 30 I.U./ml of natural HuIFN-alpha, 25 I.U./ml of recombinant HuIFN-alpha 2, and 5 I.U./ml of natural murine IFN-alpha/beta. All three IFN types inhibited significant inhibitory effect on HBsAg production during the second 24 hr-interval following their addition. After 96 hr HBsAg production had returned to normal levels. Natural HuIFN-alpha clearly depressed cellular DNA synthesis 24 hr after IFN addition which returned to normal within the next 24 hr. Recombinant HuIFN-alpha 2 influenced DNA synthesis only slightly and the mouse IFN-alpha/beta showed no effect.

Mechanism of altered cytoskeleton organization in influenza virus infection.

We followed the autophosphorylation of cytoskeleton (CS) isolated from control chick embryo cell membranes (CS-C) and from these membranes after influenza virus adsorption (CS-V) under conditions allowing to determine the activity of a single type proteinkinase. The Ca2+ dependent calmodulin (CaM) kinase used different substrates from CS-V than did the c'AMP dependent proteinkinase. The catalytic subunit (c-subunit) of the c'AMP dependent proteinkinase added from outside phosphorylated the same polypeptides than the endogenous c'AMP dependent proteinkinase, the further being more active than the latter. The purified influenza virus incorporated 32P in the presence of the c-subunit only. Incubation of influenza virus with the c-subunit caused morphological changes visible by electron microscopy. The pleomorphy of the particles as well as their electron transmissibility were enhanced in result of structural alterations and rarefaction of surface spikes of the haemagglutinin and neuraminidase. The contractibility of CS isolated from normal CEC and of the CS from CEC by 15 min postinfection (p.i.) was determined according to the actomyosin ATPase activity. The ATPase activity of the cytoskeleton in the presence of the Ca2+/CaM and that in the presence of c'AMP were used as controls. The virus as well as the Ca2+/CaM increased the ATPase activity. EGTA had no effect but did not interfere with virus stimulation, while c'AMP blocked the virus-induced enhancement of the ATPase activity.

Human interferon alfa therapy and hepatitis B virus markers in the serum of patients with chronic course of illness.

Dynamics of serum levels of HBsAg, HBeAg and anti HBc were followed during human interferon alpha (Hu IFN alpha) therapy of patients with chronic active or chronic persistent hepatitis B. More or less expressed oscillations of HBsAg serum levels seen in two out of our six treated patients seemed to occur due to IFN effect. Little and seldom changes were observed in HBeAg and anti HBc serum levels. The profiles of HBsAg serum levels of interferon-treated patients compared with the profiles of "conventionally" treated patients disclosed occurrence of spontaneous or perhaps interferon-induced cyclic elevations and depressions of HBsAg blood levels. The possible significance of this phenomenon is discussed.

Effect of human leukocyte interferon on HBsAg production in PLC/PRF/5 human hepatoma cell line.

We describe the effect of the natural human interferon alfa (HuIFN alfa) on HBsAg production in PLC/PRF/5 cells. Decreased HBsAg production was regularly demonstrated 48 hr after the treatment of cells with 3-300 IU of HuIFN alfa/ml; it lasted for further 24-48 hr depending from the amount of interferon (IFN) added. We found no differences in the sensitivity to HuIFN alfa of non-confluent cells as compared to cells which had reached confluency. The decrease of the extracellular HBsAg excretion seems to be due to inhibition of intracellular HBsAg formation.