SARS-CoV-2 IgG response in symptomatic and asymptomatic COVID-19-infected healthcare workers.

BACKGROUND: Healthcare workers (HCWs) accounted for a significant proportion of COVID-19 infections worldwide. Retrospective seroprevalence surveys are often used to screen for unidentified previous infection with SARS-CoV-2. However, the rate of humoral response in HCWs affected by COVID-19 is not well-defined. AIMS: To assess the specific IgG humoral response in symptomatic and asymptomatic SARS-CoV-2-infected HCWs and identify potential factors associated with humoral response. METHODS: We prospectively recruited 204 HCWs with RT-PCR-confirmed COVID-19 infection to evaluate SARS-CoV-2 humoral response. Serum-IgG antibodies against SARS-CoV-2 were analysed using two commercially available serological assays. A logistic regression was performed to identify independent factors associated with positive IgG serology test. RESULTS: Overall, the SARS-CoV-2 IgG seropositivity rate was 77%. This seropositivity rate was higher in symptomatic than in asymptomatic COVID-19 infection (83% versus 57%; P < 0.001) and in older HCWs.. The seropositivity rate did not diminish with time. In logistic regression, only a history of COVID-19 symptoms and age were identified as independent factors associated with the detection of anti-SARS-CoV-2 IgG antibodies. CONCLUSIONS: SARS-CoV-2 IgG antibodies are found significantly more frequently in symptomatic and in older HCWs. The fact that not all COVID-19 HCWs develop detectable IgG is vital for the interpretation of COVID-19 seroprevalence surveys.

Hepatitis B vaccination in haemodialysis patients: an underestimated problem. Factors influencing immune responses in ten years of observation in an Italian haemodialysis centre and literature review.

OBJECTIVES: Despite universal infection control precautions, the risk of hepatitis B virus (HBV) infection in patients on chronic haemodialysis (HD) remains high. For this reason anti-HBV vaccination is recommended in these subjects. In hemodialyzed patients vaccinal response is often suboptimal and it's not clear what factors may influence it. STUDY DESIGN: The aim of our study is to assess the influence of some clinical and laboratory factors on seroconversion rate after anti HBV vaccination in a cohort of patients on maintenance HD. METHODS: We analysed 60 patients on regular HD, 40 men and 20 women (age 64±12 years, range 40-88 years), immunized with Engerix B ® vaccine, followed for an average time of 62 month (12-120 months). For each patient the following data were collected: age, serum albumin (sAlb), Blood urea nitrogen before HD session (BUN), age at vaccination, dialysis vintage, presence of systemic disease, type of vascular access, dialysis modality. Correlation between these factors and anti Hbs titer was estimated with multiple regression analysis. RESULTS: Anti-Hbs seroconversion rate ( Anti Hbs > 10 IU/l) was 77%. Better rate of seroconversion (86%) was observed in patients with arteriovenous fistula (AVF) and serum albumin > 3,5 g/dL (93%), while higher rate of not responders (50%) in patients with systemic diseases. The only parameter correlated to anti Hbs titer was sAlb (p =0,0012). sAlb was correlated to age in all patients (p=0,01) and age was correlated to higher anti Hbs titer in the responder group (p=0,018). DISCUSSION: In our experience an early vaccination, when patients on chronic HD are younger and in better nutritional conditions, improves anti-HBV response.

Pigmentary mosaicism as a recurrent clinical manifestation in three new patients with mosaic trisomy 12 diagnosed postnatally: cases report and literature review.

BACKGROUND: To date, only twenty-one cases diagnosed postnatally with mosaic trisomy 12 have been reported. The most frequent phenotypic manifestations are developmental delay, dysmorphic facial features, congenital heart defects, digital alterations, and pigmentary disorders. In the present report, detailed clinical and genetic profiles of three unrelated new patients with mosaic trisomy 12 are described and compared with previously reported cases. CASE PRESENTATION: In the present report, we include the clinical, cytogenetic, and molecular description of three Mexican patients diagnosed postnatally with mosaic trisomy 12. At phenotypic level, the three patients present with developmental delay, dysmorphic facial features, congenital heart defects and skin pigmentary anomalies. Particularly, patient 1 showed unique eye alterations as bilateral distichiasis, triple rows of upper lashes, and digital abnormalities. In patient 2 redundant skin, severe hearing loss, and hypotonia were observed, and patient 3 presented with hypertelorism and telecanthus. Hyperpigmentation with disseminated pigmentary anomalies is a common trait in all of them. The cytogenetic study was carried out under the strict criteria of analysis, screening 50-100 metaphases from three different tissues, showing trisomy 12 mosaicism in at least one of the three different tissues analyzed. With SNParray, the presence of low-level mosaic copy number variants not previously detected by cytogenetics, and uniparental disomy of chromosome 12, was excluded. STR markers allowed to confirm the absence of uniparental disomy as well as to know the parental origin of supernumerary chromosome 12. CONCLUSIONS: The detailed clinical, cytogenetic, and molecular description of these three new patients, contributes with relevant information to delineate more accurately a group of patients that show a heterogeneous phenotype, although sharing the same chromosomal alteration. The possibility of detecting mosaic trisomy 12 is directly associated with the sensitivity of the methodology applied to reveal the low-level chromosomal mosaicism, as well as with the possibility to perform the analysis in a suitable tissue.

The NRF2 gene variant, -653G/A, is associated with nephritis in childhood-onset systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease associated with oxidative stress and characterized by chronic inflammation. Kidney malfunction, an aggressive characteristic of this disease, is not present in all affected individuals. The Nrf2-Keap1 pathway is important in protecting against oxidative stress and inflammation. Mouse models and genome-wide scans have suggested NRF2 (Nuclear factor (erythroid-derived 2)-like 2) as a candidate gene for susceptibility to SLE. We therefore investigated whether NRF2 polymorphisms are associated with childhood-onset SLE in a Mexican Mestizo population. Two single nucleotide polymorphisms (SNPs) were genotyped by TaqMan((R)) assays in 362 patients with childhood-onset SLE and 379 controls. We found no significant association between susceptibility to SLE and NRF2 polymorphisms. However, after population stratification by gender, the heterozygous genotype of the -653G/A SNP was significantly associated with nephritis in females only [OR = 1.81, CI (1.04-3.12), p = 0.032]. This association was stronger in females affected with severe nephritis [classes IV-VI; OR = 2.16, CI (1.12-4.15), p = 0.019]. Our results suggest that NRF2 is not associated with susceptibility to childhood-onset SLE, but it could confer a risk for developing kidney malfunction in SLE-affected individuals.

Curcumin induces p53-independent inactivation of Nrf2 during oxidative stress-induced apoptosis.

The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2) is a master regulator of a battery of antioxidant and detoxificant genes with cytoprotective function. Since Nrf2 inactivation is necessary for the complete execution of apoptosis in the presence of extensive cellular damage caused by oxidative stress, constant activation of Nrf2 may protect tumoral cells from apoptosis. The tumor suppressor gene p53 has been suggested to participate in apoptosis-related repression of Nrf2. Thus, we studied the inactivation of Nrf2 during oxidant-induced apoptosis in a p53 dysfunctional cellular model. Using curcumin dose-response assay and time-response assay in an immortalized lymphoblastoid cell line (control line 45), we observed a time-dependent increase in apoptotic markers such as deoxyribonucleic acid (DNA) fragmentation, phosphatidylserine exposure, and caspase-3, caspase-9 and poly (ADP-ribose) polymerases (PARP) cleavage. Interestingly, at early times of exposure to a proapoptotic dose of curcumin (15 µM), we observed nuclear accumulation of Nrf2 and the expression of Nrf2 target genes, whereas at late exposure times we found a reduction of total and nuclear protein levels of Nrf2 as well as downregulation of Nrf2 target genes in the absence of p53 activation. These data suggest that apoptosis-related inactivation of Nrf2 could occur in a p53 dysfunctional background, opening the possible occurrence of p53-independent mechanism to explain Nrf2 inactivation during apoptosis.

Características clínicas, virológicas, inmunológicas y psicosociales de los adolescentescon infección por HIV: 15 años después de la implementación del programa de transición / Clinical, virological, immunological, and psychosocial characteristics of adolescents with HIV infection: 15 years after the implementation of the transition program

Desde 2007, el Servicio de Epidemiología e Infectología, ha implementado un programa de transición que busca optimizar la atención de los adolescentes con infección por el HIV durante el paso de la atención pediátrica a la de adultos. Objetivo: Describir las características clínicas, epidemiológicas, virológicas y psicosociales de los adolescentes con infección HIV atendidos en el Programa y analizar el proceso de transición. Materiales y Métodos: Estudio de cohorte retrospectivo. Se incluyeron a los adolescentes, atendidos en el Programa de Transición entre enero de 2019 y diciembre de 2023, en el Hospital Garrahan, con al menos un resultado de CV y CD4+ en ese período. Se obtuvo la información de la historia clínica electrónica y se analizaron variables clínicas, epidemiológicas, virológicas, terapéuticas y psicosociales. Resultados: Se incluyeron 124 pacientes. La vía de transmisión fue vertical en el 92,74% y el estadio clínico e inmunológico era avanzado. En el momento de la transición 77,4% se encontraban con supresión virológica y con recuperación inmunológica. El 55,6% ya realizó la transición a un centro de adultos, 31,4% continúan en el programa, 11,3% se perdieron en el seguimiento y 1,7% fallecieron. Se recopilaron los datos de 31 pacientes transferidos. La mediana de seguimiento fue de 2 años; 25 pacientes (80,6%) continúan en seguimiento. Conclusiones: A pesar de la pandemia de COVID-19, el programa logró la retención de los adolescentes con infección por HIV y una transferencia sostenida en el tiempo. Además de un programa de transición estructurado para garantizar una atención continua y de calidad, es necesario continuar evaluando la evolución postransición (AU)

Since 2007, the Epidemiology and Infectious Diseases Department has implemented a transition program to optimize the care of adolescents with HIV infection during their transition from pediatric to adult care. Objective: To describe the clinical, epidemiological, virological, and psychosocial characteristics of adolescents with HIV infection treated in the program and to analyze the transition process. Materials and Methods: A retrospective cohort study was conducted. Adolescents followed in the Transition Program at Garrahan Hospital between January 2019 and December 2023, with at least one viral load and CD4+ result during that period, were included. Information was obtained from electronic medical records, and clinical, epidemiological, virological, therapeutic, and psychosocial variables were analyzed. Results: A total of 124 patients were included. The route of transmission was vertical in 92.74%, and the clinical and immunologic stage was advanced. At the time of transition, 77.4% were virologically suppressed and had achieved immunologic recovery. Of the patients, 55.6% had already transitioned to an adult center, 31.4% were still in the program, 11.3% were lost to follow-up, and 1.7% died. Data were collected from 31 transferred patients, with a median follow-up of 2 years; 25 patients (80.6%) remain in follow-up. Conclusions: Despite the COVID-19 pandemic, the program successfully retained HIVinfected adolescents and ensured sustained transition over time. In addition to a structured transition program to ensure continuous and quality care, it is necessary to continue evaluating post-transition outcomes (AU)

[Bacteremia caused by Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae. A retrospective study of 7 years]. / Bacteriemia por Klebsiella pneumoniae productora de carbapenemasa tipo KPC. Estudio comparativo y evolución en 7 años.

OBJECTIVE: Bacteremia caused by Klebsiella pneumoniae carbapenemase-producing strains (Kp-KPC) is associated with high mortality. The hypothesis of our work is that there was an increase in the levels of resistance to different antimicrobials in Kp-KPC isolated from bacteremia. METHODS: Retrospective and descriptive study in two periods: Period 1 (P1) 2010-2014 and period 2 (P2) 2015-2016. We included patients ≥18 years old with bacteremia caused by Kp-KPC in a General Hospital. We defined active drug (AD) if it was in vitro susceptible and in the case of meropenem if it had a MIC ≤ 8 mg/L in combination treatment. RESULTS: Fifty episodes of bacteremia caused by Kp-KPC were analyzed in 45 patients. (P1: 21 and P2: 29). The following variables were similar in both periods: median age (53 vs. 52 years); male sex (45 vs. 62%); site of infection: primary bacteremia (52 vs.45%), bacteremia associated with catheter (24 vs.17%), and other (24 vs. 38%). During P2 there was a significant increase in colistin resistance (28 vs. 69%) (p <0.01), an increase in MIC to meropenem ≥ 16 mg/L (74 and 97%) (p = 0.02), and decrease in tigecycline resistance (29 vs. 4%) (p = 0.02). The overall mortality was 40 in P1 and 32% in P2 (p=0.7). There was not difference in mortality when the definitive treatment was with an active antimicrobial vs. two active antimicrobials, as well as between the different antimicrobials used. CONCLUSIONS: There was a significant increase in bacteremia caused by Kp-KPC and the level of colistin resistance and MIC to meropenem. Overall mortality was high in both periods.

[Antimicrobial susceptibility of Gram-negative bacilli of community acquired intra-abdominal infections in a hospital at Buenos Aires, Argentina]. / Sensiblidad antimicrobiana de bacilos gramnegativos de infecciones intraabdominales de la comunidad en un hospital de la ciudad de Buenos Aires, Argentina.

OBJECTIVE: Community acquired complicated intra-abdominal infections (cIAI) are a common condition. Few data are available about the level of antimicrobial resistance of Gram-negative bacteria isolated from community acquired cIAIs in Argentina. METHODS: Retrospective-prospective observational study (March 2010 to February 2012). Gram-negative bacteria antimicrobial susceptibility of isolates from community acquired cIAIs were evaluated. RESULTS: During this period, a total of 85 patients were included and 138 pathogens were collected. Male sex: 58%. Median age: 33. Monomicrobial cultures were obtained in 49% of the cases. Ninety (65%) corresponded to Gram-negative organisms, and 48 (38%) to Gram-positive cocci. Gram-negative organisms most frequently observed were: Escherichia coli 76%, Klebsiella pneumoniae 8%, Pseudomonas aeruginosa 7% and Enterobacter spp. 6%. E. coli and K. pneumoniae showed a high percentage of strains resistance to ciprofloxacin of 37% and 29%, respectively. Similarly, resistance to ampicillin/sulbactam was observed in a 16% of the E. coli isolates. The prevalence of multiresistant Gram-negative organisms was 38%. CONCLUSIONS: A high level of resistance to antimicrobials was observed in community acquired cIAIs, mainly to ciprofloxacin and ampicillin/sulbactam two of the most used antimicrobial for empirically treatment of cIAIs in our country. In addition a significant proportion of multiresistant Gram-negative organisms were identified.

Harvey-ras mediated neoplastic development in the mouse mammary gland.

The role of a Harvey-ras oncogene in mammary epithelial neoplasia was examined by infecting primary cultures of normal mouse mammary epithelial cells with either the Harvey murine sarcoma virus (psi 2HaMSV) alone or with HaMSV plus a helper virus. The biological effects of expression of the Ha-ras oncogene were determined by transplanting the infected cells into gland-cleared mammary fat pads of virgin Balb/c mice. Expression of the Ha-ras oncogene was correlated with the development of mammary epithelial neoplasms. Cells infected with replication-defective HaMSV alone formed dysplastic, non-invasive mammary outgrowths. Cells infected with HaMSV plus a helper virus developed poorly-differentiated, invasive mammary epithelial tumors. Uninfected cells and cells infected with only the helper virus formed normal mammary trees. Expression of the mutant viral Ha-ras p21 was detected in dysplastic outgrowths and tumors but not in normal mammary outgrowths. Use of this transgenic organ system to genetically alter epithelium of the mouse mammary gland has permitted correlation of expression of a Ha-ras oncogene with development of mouse mammary neoplasia.

Viral Ha-ras mediated mammary tumor progression.

An immortal mammary epithelial cell line, Comma 1D, and primary cultures of mammary epithelial cells were used to examine the effects of vHa-ras on mammary tumor development. In culture, Comma 1D and primary cells were morphologically indistinguishable. Infection with a replication defective vHa-ras retroviral vector (psi ras) did not alter their in vitro phenotype. Uninfected Comma 1D cells implanted into gland-cleared mammary fat pads gave rise to dysplastic outgrowths, while implants of primary cells gave rise to normal gland structures. After psi ras infection, implants of Comma 1D cells progressed to adenocarcinomas and those of primary cells resulted in initiated dysplastic outgrowths. High level infection of either cell type with replication competent HaMSV (psi ras plus helper virus) resulted in in vitro transformation and undifferentiated in vivo tumors. Thus, in vivo analysis was necessary to detect the observed correlation between tumorigenic stage and level of infection. In this system, expression of vHa-ras was vital but not sufficient for mammary tumor initiation and progression, which resulted from an accumulation of events that did not need to occur in a specific order.

Effects of arsenite on cell cycle progression in a human bladder cancer cell line.

Bladder cancer is one of the most important diseases associated with arsenic (As) exposure in view of its high prevalence and mortality rate. Experimental studies have shown that As exposure induces cell proliferation in the bladder of sodium arsenite (iAsIII) subchronically treated mice. However, there is little available information on its effects on the cell cycle of bladder cells. Thus, our purpose was to evaluate the effects of iAsIII on cell cycle progression and the response of p53 and p21 on the human-derived epithelial bladder cell line HT1197. iAsIII treatment (1-10 microM) for 24 h induced a dose-dependent increase in the proportion of cells in S-phase, which reached 65% at the highest dose. A progressive reduction in cell proliferation was also observed. BrdU was incorporated to cellular DNA in an interrupted form, suggesting an incomplete DNA synthesis. The time-course of iAsIII effects (10 microM) showed an increase in p53 protein content and a transient increase in p21 protein levels accompanying the changes in S-phase. These effects were correlated with iAs concentrations inside the cells, which were not able to metabolize inorganic arsenic. Our findings suggest that p21 was not able to block CDK2-cyclin E complex activity and was therefore unable to arrest cells in G1 allowing their progression into the S-phase. Further studies are needed to ascertain the mechanisms underlying the effects of iAsIII on the G1 to S phase transition in bladder cells.

A new family of murine retroviral vectors with extended multiple cloning sites for gene insertion.

Murine retroviral vectors with multiple unique cloning sites in the body and 3' long terminal repeat (LTR) are described. The various alterations to the vectors include changing the gag+ start codon (AUG) to a stop codon (UAA), a deletion of 468 bp from the envelope region, and an additional 387-bp deletion of the promoter and enhancer sequences from the 3' LTR. Multiple cloning sites in the body and 3' LTR facilitate double-copy vector construction. The hygromycin resistance and luciferase genes were subcloned into the body and 3' LTR to evaluate effects of vector modifications and effects of insert location (body vs. LTR and same orientation vs. reverse orientation with respect to the vector LTRs) on virus titer. The results indicate the modifications or insert position do not negatively influence potential vector titer and expression capacity. The described vectors have potentially useful characteristics for gene therapy studies.

Protection of primary human T cells from HIV infection by Trev: a transdominant fusion gene.

Gene therapy is one of several approaches that are being tested in the search for an effective anti-human immunodeficiency virus (HIV) treatment. In this strategy, a "protective" gene would be introduced into target cells, rendering them relatively resistance to the virus-induced cytopathicity. Tat and Rev are viral proteins essential for HIV gene expression. Tat increases viral gene transcription and Rev is responsible for the nuclear export of mRNA encoding structural viral proteins. A fusion protein (Trev) was constructed, joining Tat and Rev transdominant mutant gene sequences. Previously, we showed that Trev inhibits both Tat and Rev activities in Jurkat T cells. To determine whether Trev could inhibit HIV replication in primary cells, we transferred the trev gene to peripheral blood lymphocytes and challenged them with different HIV strains. Levels of HIV p24 antigen (Ag) were reduced 4- to 15-fold in cultures of Trev-CD4+ T cells infected with two HIV primary clinical isolates and were not detectable in cultures infected with HIV strains NL4-3 and SF2. In contrast, cultures of nontransduced CD4+ T cells infected with the same viruses had levels of HIV p24 Ag up to 10 ng/ml. Trev-transduced CD4+ T cells demonstrated increased survival following HIV challenge for the length of the experiments (30 days). We did not observe rapid emergence of Trev-resistant HIV in our cultures. Following HIV challenge, cell-associated Trev protein was increased, supporting the hypothesis that cells surviving Trev expression provided a cell survival advantage. This work showed that Trev was able to inhibit HIV replication in primary CD4+ T cells, and, therefore the trev gene could be a candidate for gene therapy against HIV.

Toxicological comparison of E2a-deleted and first-generation adenoviral vectors expressing alpha1-antitrypsin after systemic delivery.

Second-generation adenoviral vectors, mutated in E2a, have been proposed to decrease host immune responses against transduced cells, reduce toxicity, and increase duration of expression as compared with first-generation vectors deleted only in E1. To test these hypotheses further, we have developed an E2a-deleted adenoviral vector expressing human alpha1-antitrypsin (hAAT). Toxicity of first-generation and E2a-deleted vectors, as determined by hematological indices, liver function tests, and histological analyses, was evaluated in C3H mice for 21 days after vector administration at increasing doses starting at 1 x 10(12) particles/kg. Both vectors induced dose-dependent abnormalities including transient thrombocytopenia, elevated ALT levels in serum, and increased hepatocyte proliferation followed by inflammation and then hypertrophy. Differences in the ratio of particles to plaque-forming units among vector preparations led to differences in hAAT expression at similar particle doses. There were no differences in toxicity between the two vectors when measured at matching levels of hAAT expression. However, the E2a-deleted vector was demonstrated to have slightly reduced hepatocyte toxicity at an intermediate particle dose. This suggests that hepatocyte toxicity is related primarily to viral entry and expression, rather than to the presence of noninfectious particles, and implies that vectors with complete elimination of viral gene expression, such as vectors with all viral coding sequences deleted, are likely to have substantial advantages in terms of safety and toxicity.

In situ gene therapy for adenocarcinoma of the prostate: a phase I clinical trial.

For patients with local recurrence of prostate cancer after definitive irradiation therapy there is no treatment widely considered safe and effective. After extensive preclinical testing of prodrug gene therapy in vitro and in vivo, we conducted a phase I dose escalation clinical trial of intraprostatic injection of a replication-deficient adenovirus (ADV) containing the herpes simplex virus thymidine kinase gene (HSV-tk) injected directly into the prostate, followed by intravenous administration of the prodrug ganciclovir (GCV). Our goal was to determine safe dose levels of the vector for future trials of efficacy. Patients with a rising serum prostate-specific antigen (PSA) level and biopsy confirmation of local recurrence of prostate cancer without evidence of metastases one or more years after definitive irradiation therapy were eligible for the trial. After giving informed consent, patients received injections of increasing concentrations of ADV/HSA-tk in 1 ml into the prostate under ultrasound guidance. Ganciclovir was then given intravenously for 14 days (5 mg/kg every 12 hr). Patients were monitored closely for evidence of toxicity and for response to therapy. Eighteen patients were treated at 4 escalating doses: group 1 (n = 4) received 1 x 10(8) infectious units (IU); group 2 (n = 5) received 1 x 10(9) IU; group 3 (n = 4) received 1 x 10(10) IU; group 4 (n = 5) received 1 x 10(11) IU. Vector was detected by PCR of urine samples after treatment, increasing in frequency and duration (up to 32 days) as the dose increased. All cultures of blood and urine specimens were negative for growth of adenovirus. Minimal toxicity (grade 1-2) was encountered in four patients. One patient at the highest dose level developed spontaneously reversible grade 4 thrombocytopenia and grade 3 hepatotoxicity. Three patients achieved an objective response, one each at the three highest dose levels, documented by a fall in serum PSA levels by 50% or more, sustained for 6 weeks to 1 year. This study is the first to demonstrate the safety of ADV/HSV-tk plus GCV gene therapy in human prostate cancer and the first to demonstrate anticancer activity of gene therapy in patients with prostate cancer. Further trials are underway to identify the optimal distribution of vector within the prostate and to explore the safety of repeat courses of gene therapy.

Suicide gene therapy for treatment of retinoblastoma in a murine model.

Children presenting with large retinoblastomas are currently treated by enucleation. As most patients are young children, the long-term repercussions of such surgery are often devastating. Subsequent radiation or chemotherapy, although effective in managing residual tumor, greatly increase the probability of the development of second malignancies later in life. Smaller tumors can sometimes be managed with local cryo- or laser surgery, thus saving the eye. The hypothesis that gene therapy could be used to reduce the tumor size sufficiently to allow local control was tested using a murine model of retinoblastoma. Y79Rb human retinoblastoma cells can be killed in vitro when transduced with an adenoviral vector containing the herpes simplex thymidine kinase gene (AdV-TK) followed by treatment with the prodrug ganciclovir. Intravitreal injections of Y79Rb cells in immunodeficient mice produce an aggressive, metastatic murine model of retinoblastoma. When these murine retinoblastomas were transduced in vivo with AdV-TK and the animals treated with intraocular injections of ganciclovir, 70% showed a complete ablation of detectable tumor. Treated animals had a significant prolongation of progression-free survival as compared with untreated controls. Gene therapy effectively reduced the tumor burden in this murine model of retinoblastoma. Thus gene therapy, in conjunction with local surgical control, may provide an effective alternative to enucleation, systemic chemotherapy, or radiotherapy for treatment of large, nonmetastatic retinoblastomas in children.

Adenoviral-mediated thymidine kinase gene transfer into the primate brain followed by systemic ganciclovir: pathologic, radiologic, and molecular studies.

Transduction of experimental gliomas with the herpes simplex virus thymidine kinase gene (HSV-tk) using a replication-defective adenoviral vector (ADV/RSV-tk) confers sensitivity to ganciclovir (GCV) leading to tumor destruction and prolonged host survival in rodents. To determine treatment tolerance prior to clinical trials, we conducted toxicity studies in 6 adult baboons (Papio sp.). The animals received intracerebral injections of either a high dose of ADV/RSV-tk [1.5 x 10(9) plaque-forming units (pfu)] with or without GCV, or a low dose of ADV/RSV-tk (7.5 x 10(7) pfu) with GCV. The low dose corresponded to the anticipated therapeutic dose; the high dose was expected to be toxic. Magnetic resonance imaging (MRI) of the brain was obtained before treatment and at 3 and 6 weeks after treatment. Animals receiving the high-dose vector and GCV either died or became moribund and required euthanasia during the first 8 days of treatment. Necropsies revealed cavities of coagulative necrosis at the injection sites. Animals receiving only the high-dose vector were clinically normal; however, lesions were detected with MRI at the injection sites corresponding to cystic cavities at necropsy. Animals receiving the low-dose vector and GCV were clinically normal, exhibited small MRI abnormalities, and, although no gross lesions were present at necropsy, microscopic foci of necrosis were present. The vector sequence was detected by polymerase chain reaction (PCR) at the injection sites and in non-adjacent central nervous system tissue in all animals. Recombinant DNA sequence was detected outside of the nervous system in some animals, and persisted up to 6 weeks. The viral vector injections stimulated the production of neutralizing antibodies in the animals. No shedding of the vector was found in urine, feces, or serum 7 days after intracerebral injection. This study suggests that further investigations including clinical toxicity trials of this form of brain tumor therapy are warranted.

Prostate-specific antigen response and systemic T cell activation after in situ gene therapy in prostate cancer patients failing radiotherapy.

In an extended phase I/II study we evaluated 36 prostate cancer patients with local recurrence after radiotherapy who received single or repeated cycles of replication-deficient adenoviral vector (ADV)-mediated herpes simplex virus-thymidine kinase (HSV-tk) plus ganciclovir (GCV) in situ gene therapy with respect to serum PSA levels, alterations in immune cells, and numbers of apoptotic cells in needle biopsies. An initial cycle of HSV-tk plus GCV gene therapy caused a significant prolongation of the mean serum PSA-doubling time (PSADT) from 15.9 to 42.5 months (p = 0.0271) and in 28 of the injected patients (77.8%) there was a mean PSA reduction (PSAR) of 28%. It took a mean of 8.5 months for the PSA to return to the initial PSA (TR-PSA) value. A repeated cycle of gene therapy failed to significantly extend PSADT but did result in significant increases in PSAR (29.4%) and TR-PSA (10.5 months). Moderately increased serum adenovirus antibody titers were generally observed 2 weeks after initial vector injection. Also at this time there was a statistically significant increase in the mean percent of CD8(+) T cells positive for the HLA-DR marker of activation in peripheral blood (p = 0.0088). Studies using prostate biopsies obtained at the same time point demonstrated that vector DNA was detectable by PCR in most samples yet all patients remained positive for prostate cancer in at least one biopsy core. Further analysis demonstrated a correlation between the level of CD8(+) cells and the number of apoptotic cells in biopsies containing cancer cells (p = 0.042). We conclude that repeated cycles of in situ HSV-tk plus GCV gene therapy can be administered to prostate cancer patients who failed radiotherapy and have a localized recurrence. Biological responses to this experimental therapy including increases in PSADT, PSAR, and TR-PSA, and activated CD8(+) T cells present in the peripheral blood, were demonstrated. Interestingly, the density of CD8(+) cells in posttreatment biopsies correlated with the number of apoptotic cells.