A new nonradioactive system for labeling molecular probes, using digoxygenine, was studied. Detection of ADN-ADN type hybrids formed on a nylon membrane was realised photochemically or by ELISA, dot-blot or Southern-blot. The high sensitivity and specificity of this new system allow to use it for detection of amounts of ADN as small as 5 ng.
Influenza virus strain A/PR8/34(H1N1) and flavonoid aqueous extract with therapeutical function were administered by intranasal route. Pathological examinations were done three and ten days after administration to evaluate the morphological modifications established in the lung parenchyma. Results showed that therapeutical administration of flavonoids had good effects on interstitial bronchopneumonia evolution till complete recovery. Flavonoid aqueous extract administered by intranasal route was well tolerated by the organism.
The closterovirus-like particles serotype III, associated with grapevine leafroll disease, were extracted from leaves by PEG precipitation and purified by differential centrifugation. The purification schedule steps were examined by enzyme linked immunosorbent assay (ELISA). The loss of virus during purification and the concentration of the preparations were estimated and the virus particles were visualised by electron microscopy.
Seventy-six venous specimens were examined by indirect immunofluorescence and histological techniques. 80.26% out of them gave negative I.F. reactions. The following causal agents were found on the I.F. positive preparations: Rickettsia burneti, Chlamydia, Mycoplasma, parainfluenza type 3 and adenoviruses, alone or associated. The most frequent lesion noted in I.F. positive specimens was of the inflammatory-dystrophic type. In I.F. negative preparations the dominant lesion was the hyalinosis of the tunica media.
Human herpesvirus 6 (HHV6) was first isolated in 1985 and included in the Herpesviridae family and the beta-herpes virinae subfamily, mainly due to its genomic similarities to the human cytomegalic virus (HCMV). HHV6 is largely disseminated in the population. The contamination takes place very early, most frequently before the age of three. In some very rare cases, a benign illness is produced, known since 1911 as Roseolum infantum or Exanthemum subitum. Seroepidemiological surveys showed that anti-HHV6 IgG antibodies were present in more than 60% of the adult population. By now, there are good information about in vitro cultivability of the virus, viral genome and proteins, epidemiology of the infection and etiopathogenic relation between virus and Exanthemum subitum. Relations between virus and lymphoproliferative diseases, some auto-immune diseases, chronic fatigue syndrome and some other diseases are less clear. Relation between this virus and HIV-infection is another problem requiring more research.
An unusual outbreak of post-vaccination reactions to 17D yellow fever vaccine occurred at Shaki, Nigeria, in May 1987. Twenty-five of the affected people were treated at the Baptist Hospital Shaki. The patients presented with rapidly progressing swelling of the left arm with associated fever and other constitutional symptoms few hours after inoculation with the vaccine. Some of the patients developed gangrene of the affected limb, five of them went into coma and died. Poor hygiene and improper handling of vaccine as well as contamination of vaccine from the source are possible causes. A review of vaccine delivery strategies especially at local community levels; sound training, supervision of vaccinators and health education are strongly recommended to prevent reoccurrence of similar reactions.
The occurrence of human viruses in the marine environment offers a vast domain of research and reflection. In this respect many findings concerning the degree of seawater viral contamination and its health implications have been accomplished. The present report synthetizes some public health aspects in connection with the viral pollution of seawater on the beaches frequented for swimming or villegiature. There are mainly envisaged the detection frequency of enteric viruses in seawater, the epidemiological aspects of this phenomenon and the virus persistence in the marine environment. A particular attention is granted to the problem of the seawater viral selfpurification.
The AIDS epidemic in Romania has properties that are both common to countries of Eastern Europe and unique to Romania. The unique aspects include the large number of cases in children infected parenterally and a relatively low but steadily increasing number of HIV infected adults. Other groups of children and adults were also exposed at risk to acquire HIV by transfusion with unscreened blood or by multiple parenteral treatments with potentially contaminated needles. Our hypothesis was that a substantial number of people in area of high endemicity was "silently" infected but did not undergo specific immune response or clinical signs. In an attempt to explore the possibility that immunization with autologous proteins (consequence of multiple transfusions) can play a role in the protection from HIV infection or in slowing down the progression of disease, we compared the incidence of autoantibodies (anti-nuclear, smooth muscle and anti-HEp-2) in a group of long survivors children with AIDS, in HIV infected children with rapid evolution and in adults at risk for parenteral acquisition of blood borne viral disease. We analyzed also the incidence of some blood borne viral infections and the presence of anti-HLA antibodies in the same groups of patients. Our results do not support the suggestion that HIV infection or AIDS can be prevented, respectively, delayed by T-cell vaccination.
Two types of cell cultures, BSC and HE-p2, have been studied from the microelectrophoretic point of view. Determinations have been made for infected cells (collected at 48 or 72 hours after infection) and for control cells, immediately after their separation from the culture, or after preserving them for 24 hours or more in migration buffer. The electrophoretical mobility increases with an average of 10% in the case of infected cells, as compared to the controls. This parameter offers a distribution of values varying from the gaussian curve to the bimodal one. From the microelectrophoretic point of view, the HEp-2 cells are more stable and respond more uniformly than BSC cells.
Five cases of vesicular enteroviral stomatitis with exanthema or hand-foot-mouth disease are described. The diagnosis was based on the clinical aspect, the Coxsackie A5 virus isolation from pathological samples, and confirmed by serological tests.
Since 1991 we studied yearly the course of some respiratory infections in nine districts of the south-east area of Romania, by collecting epidemiological and sero-viral data during the cold seasons (1) (2). The results pointed out the most frequent circulating viruses, as well as the influenza strains which caused epidemic outbreaks. The same line of investigation was followed during the cold season November 1993-- March 1994 in the mentioned geographic area. In the present study are shown the results obtained in this period.
The neurons of the network used for the simulation of a viral epidemic correspond to the individuals of the community. The activation state of the neurons reflects the contagious state of the diseased persons. Variable thresholds are introduced for the differentiation of the neuronal non-activation states (susceptible or immune subjects). The thresholds are calculated depending on the cumulated values over time of the neural activation states. The network functions synchronously. In order to follow up the state of the neural network, recurrence relations were introduced. They were applied in two epidemiological situations which differ from each other by the spreading intensity of the virus over time, reflected by the particular values ascribed to the elements of the neural connection matrix.
Sera from 35 women (patients with various clinical diagnosis: cervical dysplasia, benign and malignant tumors of the uterine cervix) were tested by immunodot blot for the presence of antibodies to E4 and E7 HPV16 proteins. A number of 26 sera displayed positivities for at least one antibody type. The mean absorbance for anti-E antibody in positive cases was higher in cancer patients (15 from 16 sera) as compared with other diagnoses (2 from 5 in dysplasia or one from 4 in uterine fibroma). Interestingly, most sera were reactive for both proteins. The high prevalence rates and high absorbance values for HPV16 E7 antibodies in association with malignant transformation suggest that the detection of these antibodies may be a useful diagnostic aid for cervical cancer--associated HPV16.
Earlier work has shown that HIV binding to CD 4 is necessary, but apparently not sufficient, for viral entry into cells. Several molecules have been proposed as potential candidates for coreceptors in HIV infection. Remarkable attention and criticism was raised by the report of Hovanessian group from Pasteur Institute, France, which claimed the role of CD 26, an enzyme also known as dipeptidyl peptidase IV, as cofactor in HIV entry and HIV infection. Present review mentions some reports which support or reject this hypothesis.
Twenty human genital tissue samples from patients with different premalignant and malignant lesions were investigated by nucleic acid hybridization, using the dot blot technique. Molecular probes of various length--whole or fragmented papillomavirus genome--were digoxygenin-labelled. Human papillomavirus 16 DNA was identified in fifteen cases, well correlated with the clinical diagnosis. Fragments of papillomavirus genome proved to be efficient probes in nucleic acid hybridization as compared with the whole genome used for the same purpose.
The most widespread use of retroviral vectors is a general purpose expression vectors for experimental researches, in eukaryotic cell culture. Some retroviral vectors have several more specialized applications in genetics and possibly in medicine. The principles of the design and construction of retroviral vectors are presented, as well as their applications and limits.
The nature of physical forces responsible for the antibody-antigen (Ab-Ag) reaction was analyzed in an original system, represented by synthetic peptides derived from the V3 consensus sequences of some HIV1 subtypes gp 120 and HIV1 positive human serum. For locating antigenic determines, flexibility, hydrophilicity and hydrophobicity profiles of the V3 peptides were analysed. The hydrophilicity indicates that V3 apex borders are involved in the first stage of the reaction. The flexibility and hydrophobicity suggest that the apex of the V3 loop (GPGR/Q) is involved in the stabilization of the complex by hydrophobic interactions. Further, we followed up the influence of the dielectric constant and of the pH upon the forces established between Ab and Ag. Modifications in the dielectric constant and pH reveal a significant contribution of electrostatic and van der Waals forces in securing the intermolecular complementarity. D2O produces the highest augmentation of the antibody affinity for the most hydrophilic peptides, while a very slight one was recorded for the most hydrophobic sequence. A high affinity of antibodies for the peptides MN, R and Z was registered at an acid pH, when their His residue was protonated. On the contrary, no influence was recorded in the case of the peptide A, which does not contain any His residue.
3'azido-3'deoxythymidine (AZT) inhibits the ability of uninfected CD4 expressing cells to participate in syncytium formation, when cocultured with cells chronically infected with human immunodeficiency virus type 1 (HIV 1). The inhibition of giant cells formation is similar, irrespective of the AZT-sensitive or resistant phenotype of the HIV1 strains. The effect on syncytium formation occurs when the uninfected target cells are pretreated with AZT, the therapeutic index varying between 290 (CEMss, H9 and > 2000 (HeLa CD4 beta gal). The syncytium reducing effect of AZT is an additional antiviral property, distinct from the inhibition of HIV replication. The HIV 1 phenotype (AZT sensitive or resistant) determines differences both in the morphology of syncytia and in the kinetics of syncytium formation. Pretreatment of the target cells with alpha interferon (125-2000 UI/ml) either alone or in combination with AZT, has no effect on the ability of these cells to participate in syncytium formation, probably owing to the basal IFN synthesis in the system.
A Previous theoretical' model (O. L. Hörer, Adriana Grigorescu Rev. roum. Virol, 1992, 43, 33) allowed us to appraise the "absorbed" mole fraction chi of chromophores, using the Multiple Light Scattering Enhanced Absorbance (MLSEA) bichromatic photometry. In the present paper the data were used to express thermodynamic parameters, based on the Gibbs free enthalpy G. In terms of the ion exchange capacity of several chromatography papers used in the former paper, the RNA chromophore distribution at the interface was correlated with thermodynamic parameter, showing characteristic patterns. The thermally denatured DNA was studied in the same way and a new insight of the helix-coil transition in terms of ionic strength was achieved.
Chronic viral hepatitis must be distinguished from other chronic liver disorders. The clinical picture associated with typical biochemical findings provides no definite information about the causative agent. An important factor, both for the patient and for the individuals in contact with him, is the evaluation of his infectivity. From 172 chronic hepatitis disorders the serological diagnosis confirmed the viral etiology in 120 patients (69.7%). HBsAg was present in 33.7% (with HBeAg in 5%), anti-HCV antibodies 22.6% and markers for both viruses in 13.4% of cases. The HCV etiology was more frequently found in chronic hepatitis (44.9%) in liver cirrhosis (50.7%). The smaller number of patients displaying simultaneously anti-HBs and anti HCV antibodies did not confirm the recent suggestions that HCV would be the most important hepatotropic virus which enhances HBsAg clearance in chronic hepatitis.
