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At least 73 records · Page 4Linked to original sources
PubMed1992

Pathology of the central nervous system in patients infected with the human immunodeficiency virus (HIV): a report of 252 autopsy cases from Brazil.

The central nervous system (CNS) was studied in 252 HIV-infected patients from the States of Rio de Janeiro and São Paulo in Brazil, the regions with the highest incidence of AIDS in the country. We compared the frequency and morphology of opportunistic infections and CNS changes caused by the HIV, with those described in other series and briefly analysed the risk factors involved in our cases. There were CNS lesions in 230 cases (91.3%), 30 (11.9%) with multiple infections and/or tumours. Most infections were opportunistic (65.4%), including 15.4% viral and 50% bacterial, fungal or protozoal infections. The most frequent was toxoplasmosis (34.1%), followed by cryptococcosis (13.5%), cytomegalovirus (CMV) infection (7.9%) and nodular encephalitis (6.7%). Primary lymphomas were observed in 4% of the cases and HIV encephalitis or leukoencephalopathy in 10.7%. Other opportunistic and HIV associated lesions were present in a limited number of cases and there were also vascular and non-specific lesions. Our study confirms the high frequency of CNS lesions in HIV infected patients. They are morphologically similar to those previously described. However, the higher incidence of toxoplasmosis and cryptococcosis, a lower incidence of viral opportunistic and HIV-associated lesions, and the presence of rarer lesions such as histoplasmosis and chagasic encephalitis, differ from other series, and may reflect geographical and/or socio-economic factors.

AIDS-Related Opportunistic Infections↗
PubMed1975

Hepatitis B antigens in serum and liver of chimpanzees acutely infected with hepatitis B virus.

We report the temporal patterns of various immunohistological and serological parameters of acute self-limited hepatitis B virus infection of two chimpanzees, and we provide evidence that the synthesis of hepatitis B core antigen precedes that of hepatitis B surface antigen. Our data suggest that existence of a biphasic hepatitis B virus infection involving a hematogenous reinfection of the liver and indicate that recruitment of liver cells to produce hepatitis B virus may occur in a pattern consistent with a replicative cycle of about 8 days.

Alanine Transaminase↗
PubMed1978

A quantitative micro-complement fixation method in studies of human wart viruses.

This report offers a description of a quantitative micro-complement fixation method (Cikes, 1975) for detecting human wart virus antigens and their specific antibodies, and proof of the specificity of the reactions being detected. The increased sensitivity demonstrated by chromium-release measurement is compared to the results of visual interpretation of complement fixation.

Antibodies, Viral↗
PubMed1992

Efficacy of inactivated whole-virus and subunit vaccines in preventing infection and disease caused by equine infectious anemia virus.

We report here on a series of vaccine trials to evaluate the effectiveness of an inactivated equine infectious anemia virus (EIAV) whole-virus vaccine and of a subunit vaccine enriched in EIAV envelope glycoproteins. The inactivated vaccine protected 14 of 15 immunized ponies from infection after challenge with at least 10(5) 50% tissue culture-infective doses of the homologous prototype strain of EIAV. In contrast, it failed to prevent infection in any of 15 immunized ponies that were challenged with the heterologous PV strain. Levels of PV virus replication and the development of disease, however, were significantly reduced in 12 of the 15 ponies so challenged. The subunit vaccine prevented infection from homologous challenge in four of four ponies tested but failed to prevent infection in all four challenged with the PV strain. Two of the four subunit vaccinates had more severe symptoms of equine infectious anemia than nonimmunized ponies infected in parallel. Both vaccines stimulated EIAV-specific cell-mediated immunity. The in vitro lymphoproliferative response was shown to be mediated by T lymphocytes and appeared to be indistinguishable from that induced by EIAV infection. Significant differences were observed in the in vivo lymphocyte responses following challenge with the two virus strains. While peripheral blood mononuclear cells from the inactivated virus vaccinates were equally stimulated by both the prototype and PV strains, the subunit vaccinates challenged with PV exhibited lower levels of spontaneous proliferation and serine esterase activity. This diminished cellular response to PV was correlated with more severe clinical disease in the same ponies. These studies demonstrate for the first time that both an EIAV inactivated whole-virus vaccine and a viral envelope glycoprotein-based subunit vaccine can provide protection against rigorous challenge levels of homologous virus but are unable to protect against similar challenge levels of a heterologous virus. Moreover, the data demonstrate that protection can be achieved in the absence of detectable levels of virus-specific neutralizing antibody in the vaccine recipients at the time of virus challenge. While vaccine-induced virus-specific cell-mediated immune responses were detected, their role in conferring protection was not obvious. Nevertheless, protection from disease appeared to be correlated with the induction of high levels of serine esterase activity following challenge. A significant observation is that while the whole-virus vaccine was usually capable of preventing or markedly moderating disease in the PV-infected ponies, the subunit vaccine appeared to have a high potential to enhance the disease induced by PV infection.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1975

Serological diagnosis of infection with the putative bovine leukemia virus.

We report on an accurate, rapid and inexpensive test for the identification of animals infected with the Bovine C-type virus (BLV). The test involves the detection of serum antibodies to BLV using the immunofluorescent (IF) technique on acetone-fixed, infected cells. The specificity of the test was demonstrated by the fact that virus was found by electron microscopy in 90% of cattle showing positive reactions. In contrast, virus was not found despite extensive examination in antibody negative animals. Thus, the presence of IF antibody is an accurate indicator of current rather than past BLV infection. In order for the IF test to be specific it is of critical importance that the target cells used are infected only with BLV. BLV antibodies can also be detected by the immunoprecipitation (Ouchterlony) technique. However, a significant proportion of BLV infected animals showing positive reactions in the IF test failed to show precipitin antibodies to the virus. Likewise, BLV infection was demonstrated by both the IF test and electron microscopy in many animals with persistently normal levels of blood lymphocytes. Thus, neither the precipitin test nor the blood lymphocyte count (Bendixen's key) can be used to rule out BLV infection.

Animals↗
PubMed1979

Selective immunodeficiency and malignant lymphoma of the central nervous system. Possible relationship to the Epstein-Barr virus.

This report presents the findings of a study of a 17-year-old male with a selective immunodeficiency to the Epstein-Barr virus, who died of a malignant lymphoma following clinical infectious mononucleosis. Autopsy findings and immunohistochemical techniques demonstrated a malignant lymphoma with B-lymphocyte characteristics which primarily involved the central nervous system (CNS). The relationship of the Epstein-Barr virus to lymphoproliferation is discussed.

Adolescent↗
PubMed1992

Confidentiality of human immunodeficiency virus status on autopsy reports. Council on Ethical and Judicial Affairs, American Medical Association.

The medical profession has long recognized the need to maintain the confidentiality of a patient's medical condition, particularly when stigmatizing conditions, like human immunodeficiency virus infections, are involved. The obligation to maintain confidentiality continues after the death of the patient. At the same time, there may be public health concerns that justify limited disclosure of a deceased person's human immunodeficiency virus status. This report provides guidelines that balance the need for confidentiality with public health concerns when a deceased person infected with the human immunodeficiency virus undergoes an autopsy.

AIDS-Related Complex↗
PubMed2025

Natural self-attenuation of pathogenic viruses by deleting the silencing suppressor coding sequence for long-term plant-virus coexistence.

Potyviridae is the largest family of plant-infecting RNA viruses. All members of the family (potyvirids) have single-stranded positive-sense RNA genomes, with polyprotein processing as the expression strategy. The 5'-proximal regions of all potyvirids, except bymoviruses, encode two types of leader proteases: the serine protease P1 and the cysteine protease HCPro. However, their arrangement and sequence composition vary greatly among genera or even species. The leader proteases play multiple important roles in different potyvirid-host combinations, including RNA silencing suppression and virus transmission. Here, we report that viruses in the genus Arepavirus, which encode two HCPro leader proteases in tandem (HCPro1-HCPro2), can naturally lose the coding sequences for these two proteins during infection. Notably, this loss is associated with a shift in foliage symptoms from severe necrosis to mild chlorosis or even asymptomatic infections. Further analysis revealed that the deleted region is flanked by two short repeated sequences in the parental isolates, suggesting that recombination during virus replication likely drives this genomic deletion. Reverse genetic approaches confirmed that the loss of leader proteases weakens RNA silencing suppression and other critical functions. A field survey of areca palm trees displaying varied symptom severity identified a transitional stage in which full-length viruses and deletion mutants coexist in the same tree. Based on these findings, we propose a scenario in which full-length isolates drive robust infections and facilitate plant-to-plant transmission, eventually giving rise to leader protease-less variants that mitigate excessive damage to host trees, allowing long-term coexistence with the perennial host. To our knowledge, this is the first report of potyvirid self-attenuation via coding sequence loss.

Plant Diseases↗
PubMed1992

Targeted gene disruption in Epstein-Barr virus.

We report the development of a method that should allow the insertion of a selective marker into any region of the Epstein-Barr virus (EBV) genome of strain B95-8 through homologous recombination with plasmids. In this method, EBV recombinants are isolated as G418-resistant, immortalized B-cell clones or as G418-resistant, latently infected subclones of Burkitt lymphoma cell lines. The presence of the productive replication origin of EBV, oriLyt, on the plasmid was found to increase the number of observed recombinant viruses by approximately 100-fold; this stimulation was observed when oriLyt was separated from the sites of recombination by several kilobases of nonhomologous DNA. Long segments of EBV DNA flanking the marker on the plasmid and/or a large plasmid size were inferred to be important for obtaining a high proportion of recombinant genomes that had recombined on both sides of the selective marker; otherwise, the recombinants that predominated had acquired the entire plasmid by recombining only on one side of the inserted marker. Therefore, to facilitate targeted insertion of genetic markers into the EBV genome, a cosmid vector carrying oriLyt was constructed and tested by using it to generate EBV mutants with the BALF2 open-reading frame disrupted.

B-Lymphocytes↗
PubMed1977

Acute measles encephalitis in children with immunosuppression.

Four cases of encephalitis occurring in children treated for lymphatic malignancies by immunosuppressive drugs are reported. Measles virus was isolated from the brain in one case and identified immunologically in another. Nucleocapsids identical to those seen in subacute sclerosing panencephalitis were demonstrated in three cases. Severe immunosuppression was evidenced in two patients by failure of rosette formation and low phytohemagglutinin tests. Pathologically, the inflammatory reaction was absent in one brain and moderate in two. Clinically, epilepsia partialis continua was a prominent feature in three patients. A history of measles or of contact was elicited in three cases, five weeks to three months before onset. All cases ran an acute fatal course. Measles virus can behave as an opportunistic invader of the central nervous system in children and the diagnosis of measles encephalitis should be considered in immunosuppressed patients.

Acute Disease↗
PubMed1978

Isolation of bovine adenovirus type 1 without an adenovirus-associated virus.

This report describes the isolation and identification of a strain of bovine adenovirus type 1 from a cow in a herd that had undergone an episode of diarrhea and abortions. This strain of bovine adenovirus type 1 did not agglutinate either guinea pig or human 0 erythrocytes, and no 20-nm virus particles were evident by electron microscopy, further indicating that it was not contaminated by adenovirus-associated virus.

Abortion, Veterinary↗
PubMed1992

Predictors of the risk of development of acquired immunodeficiency syndrome within 24 months among gay men seropositive for human immunodeficiency virus type 1: a report from the Multicenter AIDS Cohort Study.

The natural history of infection with human immunodeficiency virus type 1 (HIV-1) is characterized by a relentless decline in CD4-positive lymphocytes and the ultimate development of acquired immunodeficiency syndrome (AIDS). However, variables other than the CD4-positive lymphocyte level contribute to the measurement of risk for AIDS and can be used as predictors of AIDS onset. This study was undertaken to identify factors that, independently of the CD4-positive lymphocyte level, would predict the risk of AIDS over 24 months in a cohort of HIV-1 seropositive homosexual men receiving no antiretroviral therapy. Demographic, clinical, and laboratory data from 1,325 white, HIV-1 seropositive participants in the Multicenter AIDS Cohort Study who have been studied for 4 years were analyzed with univariate and multivariate methods. To control for stage of infection, the baseline percentage of CD4-positive lymphocytes (a known marker of disease progression), and the decline of CD4-positive cells during the first 6 months of observation were used as continuous variables. The variables that were independently associated with an increased risk of developing AIDS were: low baseline CD4 percentage, decline in the CD4 percentage during the first 6 months of follow-up, the presence of serum immunoglobulin A at baseline, decrease in hemoglobin during the first 6 months of follow-up, incident fatigue, and the interaction of decline in the CD4 percentage and incident thrush. While low CD4 percentage and other variables have been previously described as prognostic markers, decline in the CD4 percentage and the interaction of that decline and incident thrush have not previously been described as being of prognostic importance. These variables and the analytic method for estimating prognosis may prove useful for selecting and evaluating antiretroviral therapy, instituting prophylactic measures against certain opportunistic infections, and recruitment into clinical trials. Because study participants received no antiretroviral prophylaxis during the period under analysis, the method could be used to estimate the prognosis for those receiving investigational treatment were they to remain untreated, effectively making any participant in a clinical trial his own untreated control.

Acquired Immunodeficiency Syndrome↗
PubMed1975

Coxsackie B4 virus crystal formation in mouse pancreas.

For the first time, Coxsackie B4 virus crystals are demonstrated in tissues of animals inoculated with the virus. Until this report, Coxsackie B4 virus had never been found to form crystalline aggregates in tissues of any kind. The viral crystals which were located in the pancreas of newborn mice were associated with ultrastructural damage to the pancreas not observed in control animals, thereby indicating that viruses directly invade and damage these tissues. Thus, this virus must be considered among etiologic factors in pancreatic disease.

Animals↗
PubMed2025

Marburg Virus Minigenome Assays.

This chapter describes minigenome systems for Marburg virus (MARV), which reconstitute the viral polymerase complex functions of gene expression and genome replication. Procedures covered herein include passage and seeding of cells, transfection, sample collection, and reporter gene assays.

Marburgvirus↗
PubMed1979

Asymptomatic infection of mouse hepatitis virus in the rat. Brief report.

After intranasal inoculation of suckling rats mouse hepatitis virus multiplied mostly in the nasal epithelium; though there were no symptoms, antibodies were produced. Antibodies were also demonstrated in adult rats. These findings suggest that the rat may be a natural host for the virus.

Animals↗