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Although Hepatitis A virus (HAV) is transmitted by the faecal-oral route, its target for replication is the liver. Little is known of its interactions with cells of the gastrointestinal tract, and it is not known by which mechanisms HAV crosses the intestinal epithelium. In this study, it is shown that HAV associated with IgA is translocated from the apical to the basolateral compartment of polarized epithelial cells via the polymeric immunoglobulin receptor by IgA-mediated reverse transcytosis. The relevance of this mechanism, by which HAV-IgA complexes may overcome the intestinal barrier and contribute to infections of the liver, results from the fact that HAV-IgA complexes are infectious for hepatocytes and that significant amounts of intestinal HAV-IgA are present during acute infections, which are also partly transmitted. Besides supporting the primary infection, this mechanism may play a role in relapsing infections by establishing an enterohepatic cycle for HAV.

The consequences of a hepatitis A virus (HAV) infection on cell-based antiviral responses and the interactions between virus and host cells resulting in persistent infections are poorly understood. In this report, we show that HAV does inhibit double-stranded (dsRNA)-induced beta interferon (IFN-beta) gene expression by influencing the IFN-beta enhanceosome, as well as dsRNA-induced apoptosis, which suggests that both effects may be connected by shared viral and/or cellular factors. This ability of HAV, which preserves the sites of virus production for a longer time, may allow the virus to establish an infection and may be the presupposition for setting up persistent infections. Our results suggest that the inhibitory effect of HAV on the cellular defense mechanisms might not be sufficient to completely prevent the antiviral reactions, which may be induced by accumulating viral dsRNA, at a later stage of infection. However, HAV seems to counteract this situation by downregulation of viral replication and in the following production of viral dsRNA. This ability of noncytopathogenic HAV acts dominantly on cytopathogenic HAV in trans. The downregulation might ensure the moderate replication which seems necessary for inhibition of the antiviral mechanisms by HAV and therefore for the persistent state of the HAV infection.

A 27-year-old man with hemophilia type A and acquired immunodeficiency syndrome developed a subacute meningoencephalitis, associated with a normotensive internal hydrocephalus, 14 weeks before his death. From cerebrospinal fluid and brain autopsy material, a virus could be isolated and was classified by Southern blot analysis and restriction endonuclease reactions as the human polyomavirus BK. The postmortem findings of polyomavirus antigen and BK virus DNA in various cell types of the kidneys, lungs, and central nervous system strongly suggest that BK virus was the causative agent of a tubulointerstitial nephropathy, an interstitial desquamative pneumonitis, and a subacute meningoencephalitis with accentuation of the ventricular and meningeal surfaces of the brain. Besides distinctive cytopathic effects, the presence of intranuclear inclusions was a prominent histopathological feature. Therefore, the human polyomavirus BK should be regarded as a new candidate on the still growing list of opportunistic pathogens in acquired immunodeficiency syndrome.

In an effort to elucidate the mechanism of liver damage resulting from Hepatitis A virus (HAV) infection, we have studied infected skin fibroblasts and autologous lymphocytes from HAV patients. We report here that HLA-restricted virus-specific T cells play an essential role in HAV-related hepatocellular injury.

The pathogenetic mechanism leading to liver tissue injury in hepatitis caused by hepatitis A virus is unclear. We have randomly established T cell clones from liver biopsies from 4 patients with hepatitis A. A total of 578 clones was phenotypically analyzed. Whereas during the acute phase of disease CD8+ clones dominated over CD4+ clones, from a biopsy taken late after onset of clinical syndromes more CD4+ than CD8+ clones were obtained. Interestingly, in a patient with a second exacerbation of the disease, more than 20% of all clones had the CD3+ WT31- CD4- CD8- gamma delta TCR+ phenotype. Variable IFN-gamma production was observed with all types of T cell clones. All CD8+ clones had cytotoxic activity, and approximately 60% of all CD8+ clones showed specific cytotoxicity against autologous fibroblasts infected with hepatitis A virus but not with herpes simplex, adeno- or enteroviruses. These results show that the liver injury in hepatitis A is not caused by a viral cytopathogenic effect but is due to an immunopathological reaction of sensitized cytotoxic T lymphocytes against infected hepatocytes. In addition, these studies show an enrichment of CD4-8- alpha beta T cell receptor negative T lymphocytes at the site of an inflammation and suggest a role of these cells in an antiviral reaction.

Inoculation of human bone marrow with hepatitis A virus (HAV) resulted in a dose- and duration-of-incubation-dependent suppression of hematopoietic progenitor (CFU-GM, BFU-E, CFU-Mix) growth in vitro. Monocytic progenitors appeared to be least affected. While HAV inactivation by heat or beta-propiolactone and neutralization by specific antibodies completely abrogated hematopoietic inhibition, depletion of adherent bone marrow cells, and enrichment of progenitors did not alter the pattern of suppression, which also seemed to be independent of HuIFN-alpha, -beta, -gamma, and TNF. These findings support the concept that direct infection of progenitor cells by HAV may be responsible for hematologic changes commonly seen during early phases of infectious hepatitis and possibly for some cases of bone marrow failure.

Prophylactic administration of an intravenous cytomegalovirus hyperimmune globulin in bone marrow transplant recipients provided protection against primary as well as reactivated CMV infection in patients considered to be at high risk for cytomegalovirus infections. Forty-one patients were divided in six subgroups according to factors considered to increase the incidence and severity of CMV infections following bone marrow transplantation. All of these patients received blood products from donors not screened for active or latent CMV infections. In spite of this, patients undergoing intensified conditioning therapy or mismatch transplantation, as well as those transplanted in relapse of their leukemia and even patients receiving granulocyte transfusions from donors unscreened for CMV serostatus, were found not to develop primary or secondary CMV infections. Only in the group of patients older than 35 years and among those suffering from severe GVHD six patients were found to have CMV infections, only two a symptomatic form. Intravenous administration of CMV hyperimmune globulin effectively protected even patients at high risk for CMV infection against severe complications of primary infection or reactivation of this virus.

Peripheral blood mononuclear cells (PBMC) from 21 patients after bone marrow transplantation (BMT) were studied for their capacity to produce interferon (IFN) in vitro. The basal and IFN-stimulated 2-5 A synthetase activity was also investigated as a marker of the cells' ability to respond to exogenous IFN. All but one patients received cyclosporin A as a prophylaxis against graft-versus-host disease (GVHD). GVHD was diagnosed in three patients. IFN production in response to stimulation with phytohemagglutinin or poly I:C was not detectable in most patients without GVHD until 7 months after grafting. However, in a proportion of recipients without GVHD, studied early after BMT, transient normal IFN production was observed. In contrast to patients without GVHD, PBMC from patients with GVHD produced stable high levels of IFN when stimulated in vitro. The impairment of IFN production did not correlate with conditioning regimens, infection, plasma cyclosporin levels or the lymphocytes' blastogenic response to the mitogens. Addition of interleukin-2 (IL-2) to culture medium of fresh unresponsive PBMC restored only partially the defective IFN production. Similarly, T-cell lines propagated in IL-2 conditioned medium, from unresponsive PBMC, produced low levels of IFN gamma when stimulated with PHA. The basal activity of 2-5 A synthetase in PBMC from patients without GVHD could not be stimulated, during the first 3 months after BMT, by the cultivation of cells with IFN alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

A 34-year-old male patient developed an isolated pericardial relapse of an acute myelogenous leukemia (M3) 11 months after marrow grafting from his HLA-identical brother. Alloenzyme pattern analysis revealed recipient type of the myeloblasts obtained from the pericardial effusion. Recurrence of the original leukemia was preceded by a reactivation of latent cytomegalovirus (CMV) infection which, in spite of a systemic humoral immune response to the virus, persisted in the pericardium as shown by dot-blot hybridization using CMV-specific DNA fragments. Activated T cells propagated with IL-2 from the pericardial effusion did not reveal any cytotoxic or restimulation capacity on the original or relapse myeloblasts, nor on other donor, recipient or NK target cells. Local coincidence of virus persistence and leukemic relapse suggested CMV-mediated modulation of the immune response in the pericardium with consequent induction of a proliferation of the original malignant cell clone. After local chemotherapy and one course of systemic treatment the patient is still in complete remission--longer than after the marrow grafting.

Viral infections are one of the major complications after bone marrow transplantation, with high mortality and morbidity. Fourty-six patients between 3 and 48 years old (median 15 years) received orally 400 mg (under age 6, 200 mg) acyclovir 4 times daily from day -12 before to day 84 after BMT. All patients were isolated in laminar-airflow units for at least 23 days with total enteral decontamination. They were concomitantly treated with anti-CMV-hyperimmunoglobulin and cotrimoxazol. During acyclovir prophylaxis seven patients had herpes simplex virus infections, all of them were seropositive before BMT. Acyclovir plasma concentrations were measured by use of a new HPLC method. No acyclovir was present (detection limit 40 ng/ml) in the plasma of five out of six patients with HSV infections. Three of them had non-compliance, and a lack of acyclovir absorption developed in two patients under conditioning regimen. No drug-related side effects were observed. Laboratory tests did not show liver or renal toxicity. Take and hematologic reconstitution were unchanged. In our study, oral acyclovir reduced the incidence of herpes simplex infections after bone marrow transplantation. Herpes infections only occurred in patients with non-compliance or lack of acyclovir absorption.

The effect of prophylactic intravenous administration of a cytomegalovirus (CMV) hyperimmune globulin with a high titer of neutralizing antibodies plus oral acyclovir was studied in 93 consecutive bone marrow transplant recipients. In spite of receiving blood products unscreened for CMV only six patients developed CMV infections during the time they received passive immunization. Five patients reactivated virus after hyperimmune globulin infusions were stopped; four of them suffered from chronic graft-versus-host disease (GVHD) Among the patients suffering from acute GVHD grade III/IV and/or chronic GVHD the incidence of CMV infection (10/38) was significantly higher than among those with no or milder forms of GVHD (1/55) (p less than 0.01). Only three patients suffered from symptomatic CMV infections; two with gastrointestinal manifestations and one with fatal CMV pneumonia. Thus CMV prophylaxis as used here proved highly effective in combating one of the major difficulties encountered in BMT.

The age-specific and seasonal distribution of serologically confirmed hepatitis A-cases in the area of Tübingen in southern Germany is reported. During 1978-1980 most of the hepatitis A-cases diagnosed by high anti-HAV-IgM titers occurred from September to December. The age distribution of patients with German names showed two age-related peaks, the first one in young children 5-10 years of age and a second one in young adults between 20-30 years. In patients with names suggesting mediterranean origin there is only one age-related peak in early childhood. A comparison of German children with children of foreign parents born and grown up in Germany shows an earlier infection and higher infection rate in the latter. The parents of these children are almost exclusively immigrant workers from mediterranean countries. Visits of the children to the home countries of their parents in which hepatitis A is very common are supposed to be of prime importance for the high prevalence and early occurrence of hepatitis A in this group.

An influenza A strain with temperature sensitive neuraminidase was used for investigation of the functional significance of neuraminidase in different stages of the replication cycle. Heat inactivation of the neuraminidase does not diminish infectivity. Therefore, neuraminidase is not necessary for adsorption, penetration, and uncoating. At temperatures which inhibited neuraminidase activity there was also a reduction of intracellular haemagglutinin production but based on observations with a recombinant strain this was considered to be the consequence of a separate ts defect. Using quantitative haemadsorption to determine virus-dependent alteration of the cellular membrane no evidence was found that neuraminidase is involved in this process. However, release of haemagglutinin was considerably reduced if neuraminidase activity was diminished by temperature elevation. This function of the enzyme in the latest stage of the replication cycle can be substituted by V. cholerae neuraminidase.