Human Immunodefficiency Virus Research Articles

Aspects Influencing Access to HIV/AIDS Services among Afghan Immigrants in Iran: A Qualitative Study.

ABSTRACTBackground: A successful response to the risk of human immunodefficiency virus (HIV) infection among immigrants requires improved access to HIV prevention, diagnosis, and treatment services. However, most immigrants face significant challenges in accessing HIV/AIDS services. The aim of this study was to explore the aspects influencing access to HIV/AIDS services among Afghan immigrants in Iran.Methods: This was a qualitative study using conventional content analysis that was conducted from June 2018 to April 2020 in Tehran, Iran. Purposeful sampling method was performed. We conducted 25 semi-structured interviews with three groups of stakeholders including Afghan immigrants infected with or at risk of HIV (n=8), service providers (n=8), and policymakers/managers/experts (n=9). Inductive qualitative content analysis was applied according to the Granheim and Lundman method. Data were analyzed using Open Code software version 4.03.Results: Aspects influencing access to HIV/AIDS health services were categorized into 3 themes (that were extracted from 9 categories): 1. Cultural aspects (cultural similarities and differences, values and beliefs); 2. Psychosocial aspects (social support, stigma and discrimination); and 3. Service delivery related aspects (awareness, health services coverage and integrity, health services financing, accessibility, and continuity of care).Conclusion: The findings suggest that efforts to improve Afghan immigrants’ access to HIV/AIDS health services in Iran need to consider the cultural aspects, increasing HIV awareness, providing support, reducing stigma and discrimination, and improving health services coverage, integrity, financing, and continuity of accessible services.

Oral and maxillofacial manifestations of human immunodefficiency virus infection

Oral manifestations occur at all stages of human immunodeficiency virus (HIV) infection. Their clinical expressions and severity depend on the evolution of the infection and become critical at the stage of acquired immunodeficiency (AIDS). They are essentially infectious, tumoral, and, starting a few years ago, iatrogenic. Infections are mostly fungal (candidiasis), viral (herpes, zoster, human papillomavirus infections, etc.), and less frequently bacterial (streptococcemia). Cases of sexually transmitted diseases, particularly syphilis, are multiplying preoccupyingly. The most frequently observed tumors are Kaposi's sarcoma. Drug intolerance is common; the symptoms are mostly dermatological, but also oral (Stevens-Johnson syndrome and toxic epidermal necrolysis) when sulfonamides and certain antiretrovirals are used. The advent of prolonged Highly Active Anti-Retroviral Therapies (HAARTs) has led to a decline in the incidence of most opportunistic conditions, infections and tumors (except for multiple oral warts and zoster). HAARTs also provoke adverse reactions such as lipodystrophy syndromes (signs of peripheral atrophy and central hypertrophy, associated in varying degrees with metabolic syndromes). Extended survival and the new methods for prophylaxis of opportunistic infections have gradually modified diagnostic and therapeutic strategies for oral manifestations of HIV infections.

2118. Heathcare-Associated Infection in Intensive Care Patients Infected and Non-infected by Human Immunodefficiency Virus

BackgroundHealthcare-associated infections (HAI) are related with high mortality and emergence of multidrug-resistant (MDR) organisms, mainly in critical care patients. Human immunodeficiency virus (HIV) infection is a frequent cause of intensive care unit (ICU) admission, but data about HAI in this population is scarce. We aimed to evaluate HAI mortality in patients infected and non-infected by HIV in an ICU in a Brazilian public hospital and describe their epidemiological and microbiological characteristics.MethodsThis retrospective cohort included patients admitted in an Infectious Diseases ICU from July 2013 to December 2017 who acquired HAI. A database was created using SPSS and multivariate analysis was performed. Primary outcome was 30-day mortality after onset of infection. Secondary outcomes were infection caused by MDR organisms and device-associated HAI.ResultsDuring the study period, 77 ICU-patients (25 HIV and 52 non-HIV) acquired 106 HAI. HIV-patients were younger than non-HIV (45 vs. 58 years old, P = 0.002) and had more respiratory distress at admission (60.0% vs. 34.6%, P = 0.035). There was a high 30-day mortality and no difference among groups (HIV 52.0% vs. non-HIV 54.9%, P = 0.812), which was confirmed after adjusting for age, sequential organ failure assessment (SOFA) score in the day of HAI, MDR infection and more than one HAI. Central-line associated bloodstream infections (CLA-BSI) was the most frequent HAI in general population (39.6%), moreover, ventilator-associated pneumonia (VAP) was more frequent in HIV group (45.2% vs. 26.7%, P = 0.063), with similar period of invasive devices. Enterococcus faecalis was the most frequent cause of CLA-BSI in HIV group (30.0%), while Klebsiella pneumoniae was in non-HIV group (28.1%). Acinetobacter baumannii and K. pneumoniae (each 35.7%) were the predominant agents of VAP in HIV group, as Pseudomonas aeruginosa (35.0%) was in non-HIV group. Although there was a high frequency of HAI caused by MDR organisms, there was no difference among the groups (HIV 77.8% vs. non-HIV 64.3%, P = 0.214).ConclusionHIV was not associated with higher mortality in critical care patients who acquired HAI. VAP was more frequent in HIV patients, probably due to higher prevalence of respiratory conditions at admission. Infection by HIV does not increase the chance to acquire an HAI by MDR organism.Disclosures All authors: No reported disclosures.

The relationship between perceived family support and adherence to highly active anti-retroviral therapy among people living with human immuno-defficiency virus in a tertiary health facility in Nigeria

The relationship between perceived family support and adherence to highly active anti-retroviral therapy among people living with human immuno-defficiency virus in a tertiary health facility in Nigeria

Ko-infeksi Human Immunodeficiency Virus (HIV) dengan Mycobacterium leprae

Human immunodefficiency virus (HIV) epidemic covers several countries with endemic leprosy without any significantincrease in the number of patients co-infected with HIV and leprosy, so it can be concluded that HIV-positive does notincrease the risk of developing leprosy. Clinicopathological spectrum of leprosy patients who are co-infected withHIV is not changed. Leprosy may be attributed to the presence of immune recovery syndrome after the administrationof highly active antiretroviral therapy (HAART). Long-term incubation period and the low incidence of leprosy inpatients with HIV make prospective cohort or case-control studies on the prevalence of leprosy among a group of HIVpositive and HIV negative hardly possible to be performed. The benefit of this circumstance is the HIV pandemicdoes not become a nuisance of the effort to control leprosy. Further studies on the molecular pathogenesis of M.leprae and other mycobacterial can provide an understanding of the differences of the pathogenesis in patients withHIV infection.

CD4 LYMPHOCYTE IN HIV / AIDS BEFORE AND AFTER ANTIRETROVIRAL THERAPY

Abstract: Human Immunodefficiency Virus (HIV) is a virus that decreases the human immunity system, therefore the infected people become susceptible to any kind of infections. Examination of CD4 lymphocyte count periodically is one of the antiretroviral therapy success indicators. The purpose of this research was to determine the difference of CD4 lymphocyte count before and after antiretroviral therapy at Ulin General Hospital Banjarmasin on 2013-2015. The method of this research was observational analytic with cross-sectional approach. The study population was 55 patients which were selected by inclusion and exclusion criteria. Results portrayed an increase of the CD4 lymphocyte count in 51 patients after being given four kinds of antiretroviral for 6 months with the mean increase in CD4 lymphocyte count was 92,72 cell/µL. Data analysis result with Wilcoxon test portrayed a difference of the CD4 lymphocyte count before and after antiretroviral therapy with p value=0,000. In conclusion, there was a significant difference of the CD4 lymphocyte count before and after antiretroviral therapy. Keywords: Human Immunodeficiency Virus, CD4, lymphocyt, antiretroviral therapy

Flexor Tenosynovitis Due to Tuberculosis in Hand and Wrist: Is Tenosynovectomy Imperative?

The treatment of flexor tenosynovitis in the hand and wrist due to tuberculosis is controversial. Although some authors recommend the antituberculous chemotherapy, the others recommend the surgical treatment. In this article, 12 patients with synovial tuberculosis of the flexor aspect of the hand and the wrist were evaluated with respect to diagnosis and treatment modalities. None of the patients had a history of tuberculosis, concomitant disease, immunosuppressive drug use, drug abuse, and human immunodefficiency virus positivity. A chest x-ray and family screening were performed in all of the cases, none had evidence of tuberculosis in the lung. The biopsy, histopathological examination, acid-fast bacillus staining, and BACTEC tuberculosis culture were performed. Antituberculous chemotherapy was initiated in patients diagnosed with tuberculosis by either histological or microbiological examinations. The patients did not undergo any further surgery after biopsy procedures. The lesions regressed totally in all patients after 3 months of treatment. Carpal tunnel syndrome symptoms and signs recruited at five months of treatment. In patients with flexor tuberculosis tenosynovitis, it is possible to achieve good results by applying only medical therapy after a biopsy, and without the need for further surgery.

P10.22 Engineering human rhinovirus serotype-a1 as a vaccine vector

Introduction Vaccination is the optimal long-term solution to the human immuno-defficiency virus (HIV) pandemic. A majority of new HIV infections result from mucosal transmission, highlighting the need for novel vaccines that primarily generate mucosal immunity. Like HIV, human rhinovirus serotype-A1 (HRV-A1, the common cold virus) is primarily transmitted via mucosal surfaces. This makes HRV-A1 a potential vector for mucosally targeted vaccines to generate robust protection against HIV at the vaginal and other distant mucosal surfaces, and systemically. Methods Using recombinant technology, we inserted discrete overlapping fragments of HIV gag and full-length tat into the junction between genes that encode HRV-A1 structural and non-structural proteins to generate recombinant HRV-A1s (rHRV-A1s) encoding HIV Gag and Tat proteins. Results Transfection of H1-HeLa cells with rHRV-A1s transcripts yielded infectious and replication-competent rHRV-A1s with similar growth characteristics as wildtype HRV-A1. We also confirmed that cells infected with rHRV-A1s stably expressed Gag and Tat (beyond 5 passages), of the correct sizes and mainly localised in the cytoplasm as revealed by western blot assay, reverse-transcription polymerase chain reaction and immunofluorescence. These results have been recently accepted for publication in Virus Research Journal (reference number: VIRUS96578, April 2015). Conclusion To the best of our knowledge, this is the first time replication-competent and stable HRV-A1 vectors have been generated. The individual rHRV-A1gag/tat generated in this study have been mixed into a cocktail vaccine and administered intranasally to female Balb/C mice to evaluate its immunogenicity (animal experiments currently on-going). The protective efficacy of the resultant HIV-Gag-specific cell-mediated and Tat humoral responses will be documented in mice challenged intravaginally with chimeric rodent ecotropic murine leukaemia virus (EcoHIV). EcoHIV was developed by replacing the coding region of glycoprotein-120 (gp-120) of HIV strain NL4–3 with gp80 of EcoHIV to ensure that the chimeric virus infected murine cells only. Disclosure of interest statement This work was supported by a grant from The Hospital Research Foundation (THRF), Woodville, South Australia and grant number APP1026293 from the National Health and Medical Research Council (NHMRC) of Australia. TK is a post-graduate Fellow supported by THRF while SA and GE are Senior Research Fellows of the NHMRC. The authors declare no financial or commercial conflict of interest.

Large Primary Tuberculous Psoas Abscess in an HIV Patient – A Case Report

Tuberculosis (TB) remains as one of the leading opportunistic infection in patients with Human immunodefficiency virus (HIV) infection in developing countries. Here we report a case of huge primary psoas abscess of tubercular origin in an HIV patient who presented with hip pain and limping. Psoas sign was evident on examination and CT scan of abdomen revealed a large iliopsoas abscess extending from abdomen to upper part of thigh. Patient underwent percutaneous drainage of abscess and improved with anti-tuberculous drugs while continuing anti-retroviral therapy.DOI: http://dx.doi.org/10.3126/saarctb.v11i2.12437SAARC J TUBER LUNG DIS HIV/AIDS, 2014;XI(2), Page: 34-36

Prevalence and correlates of bacterial vaginosis among human immunodefficiency virus positive pregnant women at Aminu Kano Teaching Hospital, Kano, Nigeria

Prevalence and correlates of bacterial vaginosis among human immunodefficiency virus positive pregnant women at Aminu Kano Teaching Hospital, Kano, Nigeria

Interleukin 28B rs12979860 (CT/TT) Genotype Is Associated with Milder Hepatic Damage in the Natural Evolution of HCV/HIV Coinfection

Hepatitis C virus (HCV)/human immunodefficiency virus (HIV) coinfection is a major health problem, affecting mostly to individuals with exposure to blood products, as hemophiliacs or intravenous drug users, or those exposed to high-risk sexual practices. Genotyping of interleukin 28B (IL-28B) rs12979860 polymorphism is a useful tool for guiding therapeutic decisions in this disease. On the contrary, there is not enough information on the pathogenic role of this polymorphism in the natural history of the disease. The objective of this study is to describe the relationships between the CT/TT genotype of this polymorphism with viral loads and also with a number of biomarkers of liver function in coinfected patients naïve for treatment for HCV. Seventy-five HCV/HIV coinfected patients were retrospectively recruited in our Hospital from 2010 to 2011. Logistic regression analysis adjusting by [Age], [Sex], [HCV viral genotype], [HCV viral load], [HIV viral load], and [CD4 T cells levels] revealed the IL-28B rs12979860 (CT/TT) genotype as a protective factor against alanine aminotransferase (ALT) levels (>100 IU/L), aspartate aminotransferase (AST) levels (>75 IU/L), and AST-to-platelet ratio index (APRI) score for liver fibrosis (>1.5) [OR, (95% CI), p]: ALT [0.026 (0.001-0.576) 0.021]; AST [0.001 (0.000-0.297) 0.019]; APRI [0.031 (0.002-0.41) 0.008]. Stepwise regression analysis considering the same adjusting variables showed the same results. In consequence, the IL-28B rs12979860 (CT/TT) genotype, which is a marker of poor response to HCV treatment, could be mediating on the contrary a certain protective effect against the hepatic damage caused by this virus in patients coinfected by HIV.

The first needle and syringe exchange program in Iranian prisons

Background: Needle and syringe exchange programs within prisons have been reported in international literature to be associated with reduced blood-borne pathogens among intravenous (IV) drug users. Due to lack of previous evaluations for its effect on prevalence of IV drug using among Iranian prisoners, herein we decided to perform the first evaluation of this program in the Iranian prisons. Methods: In a period of nine months, from July 2008 to March 2009, 347 volunteer prisoners enrolled and followed up. All the volunteers were IV drug abusers. The program had been performed in three major prison centers in Iran, including Tehran, Isfahan and Hamadan. The prisoners were given sterile needles and syringes weekly, and the used ones were also collected regularly. Data including number of syringes and shared ones used by each person was collected at the beginning of program; and this data was also documented on a weekly basis as the program proceeded. Information regarding blood-borne diseases was also given to the enrolled prisoners continuously. Results: Among 347 volunteer prisoners enrolled in this program, an average of 17 syringes were reported to be used weekly for IV drug injection before starting the program. Moreover, the volunteers reported to use an average of 3.7 shared syringes during a week. Documented infection with blood-borne diseases (including Human Immunodefficiency Virus, Hepatitis B or C) was also found in 44 prisoners. At the end of the program, prevalence of using shared syringes among volunteers was decline to zero. Conclusion: Execution of needle and syringe exchange programs within prisons can play an important role in decreasing the number of prisoners using shared syringes and also number of shared syringes used by each prisoner. Therefore, it can greatly help medical staff with controlling blood-borne diseases. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive

Gastroduodenal opportunistic infections and dyspepsia in HIV‐infected patients in the era of Highly Active Antiretroviral Therapy

Dyspeptic symptoms are frequently reported by human immunodefficiency virus (HIV)-infected patients under highly active antiretroviral therapy. Whether opportunistic infections are a cause of dyspepsia is still unknown. In this study we prospectively compare the prevalence of gastrointestinal opportunistic infections in dyspeptic versus non-dyspeptic HIV-infected patients with advanced immunodeficiency. Six hundred and ninety HIV-infected patients under highly active antiretroviral therapy underwent esophagogastroduodenoscopy with mucosal biopsies from the stomach and duodenum. Group 1: 500 patients (161 women, 339 men; mean age 38.8 years; mean CD4 count 154.3 cells/mm(3) with dyspeptic symptoms such as epigastric pain, nausea, vomiting and fullness. Group 2: 190 patients (169 men, 21 women; mean age 40.7 years; mean CD4 count 171.6 cell/mm(3)) with no dyspeptic symptoms. Group 1: Gastrointestinal opportunistic infections were observed in eight (1.6%), and non-opportunistic parasites in two (0.4%), patients. They were: Cytomegalovirus (four patients), Cryptosporidium sp. (two patients), Schistosoma mansoni sp. (one patient), Strongyloides stercoralis (one patient) and Giardia sp. (two patients). In five patients esophagogastroduodenoscopy showed no mucosal lesions. Group 2: Giardia sp. was detected in two patients (1.1%: P = 0.07947). Gastrointestinal opportunistic infections were shown in a small number of HIV-infected patients under highly active antiretroviral therapy with advanced immunodeficiency. Although gastrointestinal opportunistic infections were detected exclusively in the dyspeptic patient group, they could not be related to these symptoms, since the number of infected patients was not statistically significant. To correctly diagnose opportunistic infections, multiple biopsy specimens may be necessary even from normal-appearing mucosa.

The amino-terminal peptide of Bax perturbs intracellular Ca2+homeostasis to enhance apoptosis in prostate cancer cells

During apoptosis, proteolytic cleavage of Bax at the amino terminus generates a truncated Bax of approximately 18 kDa (p18Bax) and an amino-terminal peptide of approximately 3 kDa (p3Bax). Whereas extensive studies have shown that p18Bax behaves like a BH3 protein with enhanced pro-apoptotic function over that of the full-length Bax (p21Bax), little is known about the function of p3Bax in apoptosis. We have previously shown that Bax and Ca2+ play a synergistic role in amplifying apoptosis signaling and that store-operated Ca2+ entry (SOCE) contributes to Bax-mediated apoptosis in prostate cancer cells. Here we test whether p3Bax can contribute to regulation of Ca2+ signaling during apoptosis through use of a membrane-penetrating peptide to facilitate delivery of recombinant p3Bax into NRP-154 cells, a prostate epithelial cell line with tumorigenic capacity. We find that human immunodefficiency virus transactivator of transcription protein (TAT)-p3Bax fusion peptide can enhance thapsigargin-induced apoptosis in NRP-154 cells, elevate SOCE activity, and increase inositol 1,4,5-trisphosphate-sensitive intracellular Ca2+ stores. Our data indicates that p3Bax can modulate the entry of extracellular Ca2+ and thus regulate the amplification of apoptosis in prostate cancer cells.

Richter’s syndrome developing in a patient with adult onset Still’s disease

Dear Editor, Autoimmune disorders can be a risk factor for the development of lymphoma [1], and at the same time, malignant lymphoma can present with paraneoplastic syndromes consisting of autoimmune phenomena and even full-blown rheumatoid disorders [2]. When a patient presents with predominant clinical symptoms of autoimmune disease awareness is necessary in order not to miss an underlying lymphoma. In this paper, we present a case that illustrates the difficulties encountered diagnosing malignant lymphoma when autoimmune phenomena dominate the clinical presentation. A 53-year old woman was referred to our hospital for a second opinion. Seven months earlier, she had been admitted elsewhere because of intermittent fevers, rigors, night sweats, anorexia, weight loss, myalgia, arthralgia, and a maculopapular rash. Before this, there was no relevant medical history. On physical examination, no pathological lymph nodes, splenomegaly, or hepatomegaly was present. Laboratory investigation revealed a leukocytosis (34.7× 10/l) with 90% neutrophils, elevated C-reactive protein (222 mg/l), liver test abnormalities [alkaline phosphatase (168 U/l), aspartate transaminase (76 U/l), alanine transaminase (49 U/l)], elevated lactate dehydrogenase (910 U/l), and hyperferritinemia (9,409 μmol/l). Additional laboratory tests and serology did not show signs of rheumatoid diseases, sarcoidosis, viral, or bacterial infections (e.g., Epstein–Barr virus (EBV), cytomegalovirus, parvovirus, human immunodefficiency virus, mycoplasma, and borrelia). Computer tomography (CT) revealed two small lymph nodes in the left axilla, but a biopsy failed to acquire representative material. Eventually, the diagnosis of adult onset Still’s disease (AOSD) was made because she met almost all criteria for this disease and no signs of a lymphoproliferative disease were found (Table 1) [3]. Treatment was started with prednisone (30 mg once daily), resulting in rapid clinical recovery. August 2006, the patient was referred because lymphocytosis (absolute lymphocyte count, 5.7×10/l) was noticed repeatedly during follow up, not accompanied by physical complaints or signs or cytopenias. After the prednisone was tapered and finally stopped, with immunophenotyping of peripheral blood (CD5, CD19, CD20, CD23, and Ig lambda positive), the diagnosis of a B-cell chronic lymphatic leukemia (B-CLL) could be established, with RAI stage 0, not necessitating therapy. A relation with the prior diagnosis of AOSD was not considered. In November 2006, she was readmitted because she experienced a recurrence of the same complaints earlier resulting in the diagnosis of AOSD. Again, leukocytosis (26.8×10/l) with predominantly neutrophils (90%) and 8% lymphocytes was seen. A skin biopsy revealed aspecific dermatitis compatible with AOSD. Because of high fever causing headaches, treatment with naproxen and paracetamol was initiated without benefit. Bone marrow biopsy confirmed the earlier diagnosed B-CLL showing small foci of lymphocytic B cells with expression of CD5 and CD23 (Fig. 1a,b). CT now revealed generalized lymphadenopathy Ann Hematol (2009) 88:81–84 DOI 10.1007/s00277-008-0526-4

Infection of human primary renal epithelial cells with HIV-1 from children with HIV-associated nephropathy

Children affected with human immunodefficiency virus (HIV)-associated nephropathy (HIVAN) usually develop significant renal glomerular and tubular epithelial cell injury. The pathogenesis of these changes is not clearly understood. Human renal tubular epithelial cells (RTEc) do not express CD4 surface receptors, and it is not clear whether these cells can be infected by HIV-1. Certain strains of HIV-1, however, have been shown capable of infecting CD4-negative epithelial cell lines. We hypothesized that the inability of laboratory strains of HIV-1 to infect renal epithelial cells may be due to a limited tropism, as opposed to wild-type viruses derived from children with HIVAN, and that viruses derived from these children are capable of infecting RTEc from the same patient. Here, we have demonstrated that HIV-1 isolates from children with HIVAN can productively infect RTEc through a CD4 independent pathway, and that infected mononuclear cells can transfer the virus to human RTEc. Human RTEc sustained low levels of viral replication and HIV-1 inhibited the growth and survival of cultured human RTEc. Thus, HIV-1 may directly induce degenerative changes in RTEc of children with HIVAN. Infected macrophages may play a relevant role in this process by transferring viruses to RTEc.

Quality control of nucleic acid amplification methods for detection of Hepatitis B virus, Hepatitis C virus and human immunodefficiency virus

Quality control of nucleic acid amplification methods for detection of Hepatitis B virus, Hepatitis C virus and human immunodefficiency virus

Papillomavirus in cervicovaginal smears of women infected with human immunodeficiency virus.

It has been described that women infected with the human immunodeficiency virus (HIV) present more frequent cytological abnormalities in cervicovaginal smears, generally related to infection by human papillomavirus (HPV). The present work is a study of cervicovaginal smears of 147 HIV-seropositive women submitted to routine gynecological examinations. The smears were stained by the Papanicolaou method. Cytopathic effects of HPV were found in 38 (25.8%) cases. Nuclear atypias of cervical intraepithelial neoplasia (CIN) were evident in 36 (24.5%) of these cases: 27 (18.4%), CIN I; 6 (4.0%), CIN II and 3 (2.0%) CIN III. Also 2 (1.4%) invasive carcinomas and one (0.7%) endocervical dysplasia were found. Other agents observed were: Candida sp, 19 (12.9%) cases, Gardnerella vaginalis, 19 (12.9%), Trichomonas vaginalis, 13 (8.4%), Chlamydia trachomatis 5 (3.4%), Mobiluncus sp 2 (1.4%) and Herpes simplex virus 1 (0.7%). This study emphasizes the high frequency of HPV/CIN cervicovaginal abnormalities in HIV-seropositive in our population. It is possible that immunological factors and sexual promiscuity are involved in this phenomenon.

Molecular Cloning and Developmental Regulation of Dictyostelium discoideum Homologues of the Human and Yeast HIV1 Tat-Binding Protein

TBP1 and 7, two human cDNA clones, are members of a large, highly conserved family that encode proteins that bind to type 1 human immunodefficiency virus Tat protein, and may be transcription factors. Two Dictyostelium discoideum homologues, denoted DdTBP 2 and 10, were isolated and characterized, and these have striking sequence similarity with both the human and yeast counterparts of the family. RNA blot analysis indicates that both DdTBP2 and 10 are developmentally regulated. Transcripts representing these cDNAs are highest in vegetatively growing cells, and their levels fall steadily throughout multicellular development and are not found in dormant or germinating spores. If indeed these proteins in Dictyostelium are also transcription factors, then this finding might indicate that only certain developmentally regulated genes require them.

Inhibition of human immunodeficiency virus type 1 reverse transcriptase by 3′-blocked oligonucleotide primers

Human immunodefficiency virus type 1 (HIV-1) reverse transcriptase (RT) (EC 2.7.7.49) with a high specific activity has been purified from the overexpressing Escherichia coli strain DH5α[pJS3.7]. Steady-state kinetics of DNA synthesis catalysed by RT were analysed on polyribo-adenylate 20-mer of (3′-5′)deoxythymidylate [poly(rA)-(dT) 20] and polyribouridylate 20-mer of (3′-5′)-deoxyadenylate [poly(rU).(dA) 20] homopolymeric template-primers. K m values of 40 and 140 nM (3′-OH ends) and k cat values of 4 and 0.14sec −1 were determined for the two different substrates. Oligonucleotide primers (dA) 20 and (dT) 20 were elongated in a terminal transferase-catalysed reaction (EC 2.7.7.31) with ddATP, 3′-dATP (cordycepin), 2′,3′-epoxy-ATP and arabino-ATP; and ddTTP, 3′-azido-TTP, 3′-dUTP, 3′-F-dTTP and rUTP, respectively. The resulting oligonucleotides were hybridized to their complementary templates and the inhibitory potential of these compounds towards DNA synthesis started from unchanged primers was measured. Oligonucleotides with unextendable 3′-groups were shown to act as strong inhibitors of DNA synthesis catalysed by HIV-1 RT. In particular, poly(rA).(dT) 20-[ddTMP] and poly(rU).(dA) 20-[3′-dAMP] were potent competitive inhibitors, displaying k i values of about 6 and 12 nM, respectively. Also 3′-azido-, and 3′-fluoro-terminated oligonucleotides showed competitive inhibition with inhibition constants in the range of 20–35 nM. In contrast, 2′,3′-epoxy-terminated (dA) 21 displayed a mixed-type inhibition with a if K ivalue of 67 nM. Arabino-terminated (dA) 21 was found to be an uncompetitive inhibitor of HIV-1 RT with an inhibition constant of 318 nM. Arabino-terminated primers did not act as strict chain terminators because they could be elongated by HIV-1 RT. This study provides information on the structure-activity relationship of modified 3′-termini of primer molecules which might be exploited as inhibitors of HIV in the future.