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PubMed1992

Host factors associated with HIV-related oral candidiasis. A review.

Human immunodeficiency virus (HIV)-related oral candidiasis affects approximately one third of HIV-seropositive patients and more than 90% of patients with AIDS. It is necessary to identify patients who have a greater risk of candidiasis developing, so that interventions can be designed to reduce the frequency. This is particularly important because there is evidence that Candida species are immunosuppressive and therefore candidiasis may adversely affect the prognosis of patients with HIV. Susceptibility to HIV-related oral candidiasis is associated with xerostomia, severity of disease, depression of cell-mediated immunity, and older age (greater than 35 years). The frequency of HIV-related oral candidiasis is notably increased when the CD4 lymphocyte count falls to less than 300 cells/mm3. Xerostomia appears to be a better predictor of HIV-related oral candidiasis than CD4 count and should be prevented (e.g., by avoiding xerogenic drugs) and treated, when necessary, to minimize the risk of oral candidiasis.

Acquired Immunodeficiency Syndrome↗

PubMed2026

AP2: an indispensable host factor in virus infection.

Adaptor protein complex 2 (AP2), a central regulator of clathrin-mediated endocytosis and intracellular cargo trafficking, is hijacked by numerous viruses to complete their infectious cycles. This review systematically synthesizes the multifaceted roles of AP2 across the entire viral life cycle, from entry and replication to assembly and release, as well as in immune evasion. By delineating how diverse viruses exploit this key host machinery, we further consolidate the rationale and current progress in developing broad-spectrum antiviral strategies that target AP2 and its regulatory pathways. This work aims to provide a unified perspective on AP2 as a critical host-pathogen interface, offering new insights into viral pathogenesis and antiviral drug discovery.

Humans↗

PubMed1975

Host factors in the susceptibility of rheumatic patients to streptococcal infections.

In children and adolescents who each had at least one previous episode of rheumatic fever and who were not maintaining effective anti-streptococcal prophylaxis, the attack rates of subsequent streptococcal infections declined with advancing age, but were unaffected by gender, cardiac status, or multiplicity of antecedent rheumatic episodes. The rate of rheumatic recurrence per streptococcal infection fell with advancing age, but rose with increasing amounts of cardiac damage and with multiplicity of previous rheumatic attacks. The results suggest that the underlying clinical features of the host have a greater effect on the rheumatogenicity of an acquired streptococcal infection than on the ability to avoid the infection.

Acute Disease↗

PubMed1978

Exclusion of bacteriophage T1 by bacteriophage lambda. I. Early exclusion requires lambda N gene product and host factors involved in N gene expression.

Two modes of exclusion of T1 by lambda are distinguished. "Early" exclusion depends on gene N, but not on gene Q. It is at least partially ineffective against T1am23. "Late" exclusion depends on gene Q and effects T1am23 as well as T1+. Early exclusion is a direct effect of N gene product, rather than N gene being required for the expression of some other lambda gene. Three host mutations, groN, nusA, and nusB, known to interfere with lambda replication by affecting N gene expression, also interfere with the ability of lambda to exclude T1.

Coliphages↗

PubMed1972

An inhibitory protein of Escherichia coli RNA polymerase in bacteriophage T3-infected cells (core polymerase-sigma factor-host polymerase-phage polymerase-initiation).

A partially purified protein isolated from bacteriophage T3-infected cells of Escherichia coli B markedly inhibits the activity of E. coli RNA polymerase, slightly inhibits the activity of purified T3 polymerase, and does not inhibit the activity of either core polymerase or the ribosome-bound T3 polymerase. The properties of this protein and its mechanism of action have been studied. It appears to antagonize the action of the sigma factor component of RNA polymerase.

Bacterial Proteins↗

PubMed1972

Host factors and capsular typing of body fluid isolates in fulminant pneumococcal infections.

A 10-year retrospective study was made to determine the spectrum of underlying disease in, and the capsular types of pneumococci isolated from, blood and body fluids of 140 hospitalized patients. Fifteen serotypes were found among 82 typed isolates, 53% of which were types 8, 14, or 23. There was a predominance of males and a high incidence of underlying pneumonia, chronic liver disease, nephrotic syndrome, cerebrospinal fluid rhinorrhea, and malignancy. Mortality rates were higher among the very young and aged, and the immunologically comprised host at either extreme of life was more susceptible to disseminated pneumococcal infection. Pneumococci of the higher capsular types were prominent in children, and those of the lower types in adults, a finding in agreement with other recent studies.

Adolescent↗

PubMed1987

New microbial and host factors in disseminated gonococcal infection: case report.

Disseminated gonococcal infection was diagnosed in an immunocompromised patient who presented with oliogoarthropathy and tenosynovitis. The gonococcal isolate was prototrophic, showed intermediate resistance to penicillin, and belonged to serogroup WII/III. An isolate from the patient's sexual contact showed similar characteristics. The patient had a Saccharomyces opsonin defect, which is associated with childhood infections and has not been reported previously in association with disseminated gonococcal infection. The pathogenetic importance of the unusual isolate and the underlying host defence defect is considered.

Adolescent↗

PubMed1998

Host factors affecting the homologous and heterologous immune response of cattle to FMDV: genetic background, age, virus strains and route of administration.

Sixty bulls were tested for antibodies to the heterologous serotype C1 of FMDV following repeatable vaccinations with a commercial trivalent vaccine (O1, A22, Asia1). Six (10%) bulls were found to possess rather high levels of heterologous neutralizing antibodies which showed accumulative trend with age. Two high positive and two negative bulls for the heterologous serotype C1 were selected for progeny test involving ten daughters of each bull. The four bulls, either positive or negative for the heterologous serotype C1, showed significant phenotypic correlation between their heterologous and homologous titers (O1, A22, Asia1). This correlation between heterologous and homologous antibody titers was not found in the daughters of these bulls. However, two of ten daughters of one positive bull, to C1 showed individual high titers (> or = 1.5). The intradermal (ID) as compared to subcutaneous (SC) route of administration resulted in higher rate of responders to both heterologous serotypes C1 and SAT1. The heterologous immune response to FMDV in Israeli-Friesian cattle was found to be related to the age of the host, multiplicity of vaccinations, route of vaccination, kind and numbers of the antigens used in the vaccine. The homologous immune response is also controlled by genetic factors.

Age Factors↗

PubMed1991

[Study of the host factors in the occurrence of the postoperative infections--special reference to the pathogenicity of the Enterococcus and MRSA].

A study of the pathogenicity of the Enterococcus and Methicillin resistant S. aureus (MRSA) was made of 781 cases with gastroenterological surgery. The results obtained were summarized as follows. In this study 215 strains were isolated from clinical specimens. In these strains 13% was isolated from the postoperative mixed infection and only 7% occurred in single infection. Most of the single infections by the Enterococcus occurred in the cases with changes in host resistance, such as terminal cancer, disorder of the glucose tolerance, malnutrition and/or organ failures. Seventy-three strains were isolated from clinical specimens. In these strains 10% were the postoperative mixed infection and 40% were single infection. Incidence of the infection by the MRSA was significantly high compared with that by the Enterococcus. Single infection by the MRSA occurred even in the cases with normal host resistance. Strains producing enterotoxin C (single or plus A) were frequently isolated in MRSA enteritis or pneumonia. However, 60 percent of the patients in whom MRSA were detected in their abdominal drains had no signs of infection. These results suggest that the occurrence and severity of the MRSA infection relate with site of the infection and production of the exotoxin.

Enterococcus↗

PubMed1984

Host factors in the pathogenesis of urinary tract infections.

Classic animal studies conducted two decades ago provided the basic understanding of the pathogenesis of urinary tract infections. Those studies emphasized the natural resistance of the urinary tract to colonization and infection. Urinary obstruction, stasis, and reflux remain of great importance in all age groups in predisposing to infection. Recent studies of the crucial role of bacterial adherence to epithelial cells lining the genitourinary tract have shed new light on the pathogenesis of urinary infection. Information from adherence studies may have considerable clinical relevance with regard to the development of vaccines that prevent bacterial invasion particularly in the upper urinary tract. The normal defense mechanisms present in the human urinary tract are discussed. Despite progress in our understanding of the pathogenesis of urinary infection, considerable controversy still exists particularly with regard to host susceptibility to recurrent lower urinary tract infections in women with anatomically normal urinary tracts. Recent studies also have emphasized the significance of the host's normal immunologic mechanisms in contributing to intrinsic renal damage after upper urinary tract invasion by bacteria.

Adult↗

PubMed1981

[Host factors in asbestos-associated disease. A study in twins (author's transl)].

Observations in two pairs of identical twins illustrate the importance of genetic factors in determining the outcome of exposure to asbestos in relation to pleural plaques and bronchogenic carcinoma. The first pair of twins, laggers with french railroad (S.N.C.F.), were discovered fortuitously, after only several years exposure, to have bilateral pleural plaques and calcification at the same site on the axillary and diaphragmatic surfaces. The second set of twins developed epidermoïd bronchial carcinoma : one at the right hilum, the other postero-basally on the right in 1969 and 1977 respectively. Both were in ship-building and each had been exposed to asbestos in the same yard for 20 years between 1945 and 1965. Radiographs showed left sided pleural calcification and reticular shadowing at the bases in the two cases. These observations show the role of the host in the generation of asbestos disease. They are in keeping with studies on the presence of certain tissue types (HLA B27, and HLA B8) in those with asbestosis and of non-specific auto-antibodies (anti-nuclear factor, rheumatoid factor) in asbestosis, silicosis and the idiopathic pulmonary fibrosis. The relation between genetic factors and asbestos-induced cancer is suggested by the variable susceptibility of different kinds of animals to carcinogenesis in response to asbestos and by the increased inductibility of the enzyme system Aryl-hydrocarbon-hydroxylase in subjects exposed to this air-born contaminant who develop pleural tumours and/or bronchitis. There are only two other publications of bronchial carcinoma in twins in the literature.

Adult↗

PubMed1994

Effect of genetically determined host factors on the efficacy of vidarabine, acyclovir and 5-trifluorothymidine in herpes simplex virus type 1 infection.

The susceptibility of Herpes simplex virus (HSV) to acyclovir (ACV), 5-trifluorothymidine (TFT) and vidarabine (Ara-A) in HSV-infected embryo fibroblasts from BALB/c and C57BL/6 mice as well as Vero cells were measured. Ara-A and TFT (at its highest concentration) were more effective in Vero cells and BALB/c mouse embryo fibroblasts (MEF) than in C57BL/6 MEF. In contrast, ACV was more effective in C57BL/6 MEF than BALB/c MEF and Vero cells. These data suggest that genetically determined differences in the ability of host cells to support the replication of HSV influence the activity of antiviral drugs.

Acyclovir↗

PubMed1976

Host factors and antibody response Haemophilus influenza type b meningitis and epiglottitis.

Levels of antibody in serum after infection with Haemophilus influenza type b or challenge with polysaccharide vaccine are highly variable. Convalescent-phase serum antibody to the capsular polysaccharide of H. influenzae type b was measured in two groups of patients with pathophysiologically distinct diseases, meningitis and acute epiglottitis. Antibody response after H. influenzae meningitis was subnormal. Mean levels of antibody, the distribution of antibody levels by age, and erythrocyte and genetic marker lymphocyte antigens were studied; all results suggested that these two groups of patients were genetically and immunologically different from each other. Evidence suggested that the magnitude of the important host immunologic response was under host genetic control.

Adolescent↗

PubMed1989

Non-secretion of ABO blood group antigens: a host factor predisposing to recurrent urinary tract infections and renal scarring.

In a study of 718 women referred for specialist investigation for recurrent urinary tract infections, 250 (34.8%, P less than 0.01) were non-secretors. The proportion of non-secretors among the women with renal scars (42.6%) was higher than that found for women with no evidence of renal scars (36.6%). Among 29 patients in whom symptoms began in childhood or adolescence, 51.7% were non-secretors. The proportion of non-secretors among individuals with renal scars in this study (42.6%) and that reported in the accompanying paper for Swedish children (40%) suggests that non-secretion might influence the pathogenic sequelae of these infections. Possible host-parasite interactions underlying the increased proportion of non-secretors among women with recurrent urinary tract infections and those leading to development of renal scars are discussed.

ABO Blood-Group System↗

PubMed1992

Reproductive activity of Synosternus cleopatrae (Siphonaptera: Pulicidae) in relation to host factors.

Reproductive activity of Synosternus cleopatrae (Rothschild) infesting Gerbillus andersoni allenbyi Thomas was studied in a natural setting in Israel. Rodents were trapped and measured (weight and length), their sex was identified, and their reproductive status estimated. Their ectoparasites were removed, and fleas were dissected and their oocytes measured. Two indices of flea reproductive activity were analyzed: "reproductive status," which distinguished between gravid and nongravid females, and "reproductive intensity," which was estimated as the sum over the two largest oocytes of the products of oocyte length multiplied by oocyte width. Both indices showed that no reproduction took place between November and January, but reproduction was relatively stable during the rest of the year. Although flea reproductive activity differed significantly among individual hosts, only a small fraction of gerbils (10-15%) carried a significantly different proportion of reproductive fleas than their monthly sample proportion (based on all fleas regardless of hosts). All these hosts carried a lower proportion of reproductive fleas than their monthly sample proportion. The host's sex, but not reproductive status or age, had a significant effect on flea reproduction, expressed as a higher reproductive activity on male gerbils. Infestation burden expressed as ectoparasite counts was included in the statistical analysis. Only lice, Polyplax gerbilli Ferris, but not S. cleopatrae, Stenoponia tripectinata (Tiraboschi), and a total of five mesostigmatid Acari had a significantly negative association with S. cleopatrae reproductive activity. These relationships between S. cleopatrae reproductive activity and the host infestation burden do not support the hypothesis of modulation of S. cleopatrae reproduction by the infestation burden. However, differences in the reproductive activity of ectoparasites between their hosts may play a major role to generate the parasite clumped distribution. Thus, gerbil males probably carry more fleas than gerbil females because of the higher reproductive activity of S. cleopatrae on gerbil males.

Animals↗

PubMed1988

Virulence of Escherichia coli in relation to host factors in women with symptomatic urinary tract infection.

The relationship between bacterial characteristics and the severity of urinary tract infection in adults has not been clarified. In this study, Escherichia coli strains (n = 178) were prospectively collected from women with community-acquired urinary tract infection. The isolates were identified by O:K:H serotype and characterized for adherence, hemolysin production, and serum bactericidal resistance. The patients had acute pyelonephritis with or without complicating factors and acute cystitis. Nine serotypes (O1:K1:H7, O1:K1:H-, O2:K1:H-, O4:K12:H1, O7:K1:H-, O9:K34:H-, O16:K1:H6, O16:K1:H-, and O75:K5:H-) comprised 65% of the strains in uncomplicated pyelonephritis, but were significantly less often encountered in complicated pyelonephritis or cystitis. Adherence was the single property most characteristic of the pyelonephritogenic clones. Adhesins specifically recognizing Gal alpha 1----4Gal beta-containing receptors occurred in 80% of strains in uncomplicated pyelonephritis, in 50% of strains in complicated infections, and in 37% of cystitis strains. Hemolysin production and serum resistance did not correlate with any disease pattern. Advanced age did not seem to reduce the selection of virulent E. coli to cause pyelonephritis. These results demonstrate in women a relationship between E. coli virulence and the severity of urinary tract infection analogous to that previously observed in pediatric populations and also illustrate the balance between host resistance and bacterial virulence in the urinary tract.

Acute Disease↗

PubMed1990

Structure-specific binding of wound tumor virus transcripts by a host factor: involvement of both terminal nucleotide domains.

A gel retardation assay was used to demonstrate binding of wound tumor virus transcripts by a protein component of leafhopper vector cell extracts. Comparative binding studies employing terminally modified and internally deleted transcripts established that the segment-specific inverted repeats present in the terminal domains of the viral transcripts were necessary but not sufficient for optimal binding. An additional involvement of internal sequences in either the formation or the stabilization of the binding complex was indicated. Results of competitive binding experiments confirmed the sequence- and structure-specificity of the protein-RNA interaction and revealed apparent differences in the ability of individual viral transcripts to form a stable binding complex. Possible implications of structure-specific interactions between wound tumor virus transcripts and a host component and the role of the terminal inverted repeats are discussed.

Animals↗

PubMed1990

Transcription-dependent competition for a host factor: the function and optimal sequence of the phage lambda boxA transcription antitermination signal.

Ordered development of lambdoid phages relies on systems of transcription termination and antitermination. The phage-encoded N early regulatory proteins, acting with the Nus proteins of Escherichia coli, modify RNA polymerase to a form that overrides many transcription termination signals. These modifications require cis-acting sites, nut, located downstream of the early phage promoters. The nut sites in phages lambda, 21, and P22, which share similarities but are not identical, contain two signals, boxA and boxB. We demonstrate that although a consensus sequence for the boxA signal (boxAcon), 5'CGCTCTTTA, is found only in P22, changes to consensus in the nutR sites of lambda and 21 create more effective antitermination signals than the wild-type signals. An in vivo competition assay demonstrates that a lambda nut region with boxAcon outcompetes nut regions with wild-type, as well as other variations of the boxA sequence, for the host NusB protein. This suggests that boxA influences NusB activity in N-mediated antitermination. Successful competition by boxAcon requires transcription of the nut site as well as N activation. Nucleotide replacement further demonstrates that bases at both ends of boxA are important for antitermination.

Bacterial Proteins↗