Ramón Alberto de Torres

Enterocin CRL35 inhibits late stages of HSV-1 and HSV-2 replication in vitro

The replication of herpes simplex virus (HSV) type 1 and 2 in Vero cells is inhibited in the presence of enterocin CRL35 (ECRL), a bacteriocin produced by Enterococcus faecium CRL35. Attempts to resolve the mode of action of ECRL indicate that virus adsorption and penetration are not affected. Instead, a late step of virus multiplication is hindered since the addition of 100 microg/ml of ECRL at 8h post infection still causes a 90% inhibition of virus release. The effect of ECRL on HSV antigen expression was studied by immunofluorescence using a polyclonal serum and a monoclonal antibody against glycoprotein D (gamma protein). These studies indicated that ECRL impeded the second round of infection, apparently as a consequence of the inhibition of glycoprotein D expression. The replication of syncytial mutants of HSV-1 was significantly inhibited at a ECRL concentration of 25 microg/ml. Both the percentage of fused cells and the polykaryocyte size were affected. Studies on the effect of ECRL on viral protein synthesis showed that in the presence of ECRL, HSV late gamma proteins were not synthesized. From these findings, it is concluded that inhibition of HSV spreading by ECRL is due to the prevention of mainly late glycoprotein synthesis.

Antiviral activity of enterocin CRL35 against herpesviruses

Enterocin CRL35 is an antibacterial polypeptide of 3.5 x 10(3) Da produced by Enterococcus faecium CRL35. A series of experiments are described that show the enterocin also had antiviral activity against thymidine-kinase positive (tk+) and deficient (tk-) strains of herpes simplex (HSV) type 1 and 2 in Vero and BHK-21 cells. This activity was observed at 100 microg/ml, 15-fold lower than the cytotoxic concentration. In both cell lines there was a 2 log inhibition of infectivity. The compound inhibited viral multiplication in a dose-dependent manner and had no virucidal effect. Enterocin CRL35 also inhibited the virion-associated host shutoff in infected Vero cells showing that intracellular viral multiplication was affected.

Incidence of Chlamydia trachomatis and other potential pathogens in neonatal conjunctivitis

OBJECTIVE Ocular infection in neonatology is a permanent and important health problem. To improve primary attention, prevention, and control, the study of the potential bacterial etiology of all consecutive cases of conjunctivitis was incorporated as a regular procedure in primary care from July 1995 to December 1998. MATERIALS AND METHODS Prof. A. Posadas Hospital (Great Buenos Aires) has an average of 4294 births per year. This report analyzes the results obtained in 332 infants (age range, 0-30 d) with conjunctivitis. Clinical conjunctivitis was diagnosed in inpatients and outpatients by the same specialized staff. Isolation and characterization of bacteria were done by conventional microbiologic methods, including specific search for Neisseria gonorrhoeae and Chlamydia trachomatis. Chlamydia trachomatis was studied by antigen immunodetection and polymerase chain reaction, and genotyped by restriction fragment length polymorphism. RESULTS Conjunctivitis had an incidence (cases per 1000 live births) of 39.6 in 1995, 25.3 in 1996, 15.4 in 1997, and 15.2 in 1998. Microbial growth was detected in 167 (50.3%) of 332 cases. Ocular C. trachomatis infection was detected in 26 cases (7.83%). Five of seven isolates in tissue cultures belonged to type E and two to type G. Bacteria from respiratory ecology were the main isolates: Haemophilus influenzae (16.9%), Streptococcus pneumoniae (12.3%), and Staphylococcus aureus (8.7%). Haemophilus influenzae isolates were not serotyped and 17.2% of them were b-lactamase producers. In 15 cases both H. influenzae and S. pneumoniae were isolated together. Of S. pneumoniae, 4.9% were oxacillin resistant. CONCLUSIONS There has been a decline in the total number of cases of neonatal conjunctivitis, but the disease is still an important health problem. Chlamydia trachomatis also shows a decreasing profile with an incidence of (cases per 1000 live births) 4.39 in 1995, 1.85 in 1996, 1.01 in 1997, and 0.78 in 1998, and a tendency to show more incidence in spring-summer and significant accumulation of cases in babies between 7 and 9 days of age. Haemophilus influenzae alone (12.3%) or associated with S. pneumoniae (4.5%) appears as a prevalent potential bacterial pathogen. A significant accumulation of H. influenzae and S. pneumoniae cases occurs in winter. In 47.6% of cases, there was no bacterial growth. No significant seasonal differences in percentage of negative cultures or among the three-day age groups were detected. Neisseria gonorrhoeae was not found associated with ophthalmia neonatorum in this series.

Antiviral effects of Melia azedarach L. leaves extracts on Sindbis virus-infected cells

Partially purified extracts from leaves of Melia azedarach L. (MA) exert a broad range of antiviral effects on DNA and RNA viruses. The effect of MA on different stages of Sindbis virus replicative cycle in BHK cells was investigated. Under one-step growth conditions MA afforded a greater than 90% inhibition in virus yield if added to the cell cultures 2 h before or after infection, and when added 4 h after infection MA still caused a greater than 80% inhibition. Analysis of early events following Sindbis virus infection showed that MA did not affect viral adsorption to or penetration in BHK cell. In contrast, viral RNA and protein synthesis was almost totally inhibited in cells pretreated with MA 2 h before infection, while cellular macromolecular synthesis was similar in MA-treated and untreated cell cultures.

Isolation of yeast with killer activity and its breeding with an industrial baking strain by protoplast fusion

Summary“Wild” strains of Saccharomyces cerevisiae were isolated from dairy products, bakery goods, fresh fruit and vegetables, and tested for killer activity. Four isolates out of 238 strains possessed killer activity. The best of these was converted to the petite form and hybridized with an industrial strain of Saccharomyces cerevisiae by protoplast fusion. Thirty-eight out of 104 isolates had killer activity, and some of these had good dough-raising activity as well.

Prevalencia de microorganismos asociados a secreción genital femenina, Argentina

OBJECTIVE There was a significant increase in the number of women demanding gynecological care in public hospital of the Great Buenos Aires, Argentina, between 1997 and 1998. It was necessary to update the prevalence of associated microorganisms in order to review the laboratory support and adjust prevention and control guidelines. METHODS Samples from vaginal and endocervical discharge, from total cases: 84 adolescents (15 to 19 years) and 784 adults (20-60 years) attended in 1997-1998, were studied. Neisseria gonorrhoeae, Streptococcus agalactiae, Trichomonas vaginalis, Candida spp, and bacterial vaginosis, were diagnosed applying direct detection methods and specific culture isolation. Chlamydia trachomatis (antigen detection), Ureaplasma urealyticum and Mycoplasma hominis (culture) were also studied in part of the population. RESULTS Patient care increased steadily from 1997 and there was an increase of 2.1 times from the first semester to the last one in 1998. Bacterial vaginosis was the most prevalent disease in the adult group, with 23.8%; followed by Candida spp 17.8%; S. agalactiae 5.6%; T.vaginalis 2.4%. In 50.3% of total adult cases neither bacterial vaginosis or presence of any sought microorganisms, was detected. In the adolescents group the most frequent detection was Candida spp with a 29.7%; bacterial vaginosis in 17.8%; followed by S. agalactiae 3.6%, T.vaginalis 2.4%. Also in this group on an important number of cases, 46.4%, none bacterial vaginosis or the presence of the sought microorganism were found. In some of the adult group, C. trachomatis (7/400) 1.76%, U. urealyticum (209/340) 61.4% and M. hominis (45/272) 16.5% were detected. CONCLUSIONS Bacterial vaginosis and Candida spp prevalence is important in both groups. The absence of N. gonorrhoeae and lower prevalence of T. vaginalis and C. trachomatis is remarkable. A high prevalence of U. urealyticum and M. hominis were also detected, but the actual pathogenic role in adult women is still under discussion. The significant increase of attendance in the public system is due to social changes in the population and not due to changes in any particular pathology. Laboratory support has to be adjusted to the most cost-effective procedures to solve the most prevalent problems.

Induction of a refractory state to viral infection in mammalian cells by a plant inhibitor isolated from leaves of Melia azedarach L

A partially purified plant inhibitor (Meliacin) isolated from Melia azedarach L induced in cells a refractory state to virus infection. Meliacin was active in a large variety of continuous and/or primary cell cultures. A state of maximum virus resistance was achieved after 2 h of incubation and was maintained for at least 15 h; later on it declined but it was fully regained after a second pulse of Meliacin. Interferon was not detected in the supernatant of cells treated with Meliacin and a measurable increase in ds-RNA dependent protein kinase activity was not observed in extracts of Meliacin-treated cells. The antiviral state was not transferred by either extracellular fluid or direct cell-to-cell contact. An active cell metabolism was required for Meliacin action, which was partially reversed in the presence of actinomycin D. It appears that Meliacin is not an interferon-like substance, which induces an antiviral state based on a still unexplained mechanism.

Perfil microbiológico en secreciones genitales de embarazadas sintomáticas, en el Gran Buenos Aires, Argentina

Fundamentos Conocer la prevalencia de microoorganismos asociados a secrecion genital en embarazadas sintomaticas. Actualizar su evolucion y reajustar protocolos de laboratorio, en un Hospital Publico del Gran Buenos Aires (Argentina). MEtodos. Deteccion en secrecion vaginal y endocervical, de Chlamydia trachomatis, Neisseria gonorrhoeae, Streptococcus agalactie,Trichomonas vaginalis, Candida spp., Mycoplasma hominis, Ureaplasma urealyticum y vaginosis bacteriana (VB). Se utilizan metodos directos, cultivo, inmunodeteccion y reaccion en cadena de la polimerasa. En 1999; se estudiaron consecutivamente 198 embarazadas sintomaticas con edades entre 16 y 42 anos (mediana 27 anos). Resultados En 51 casos (25,7%) no se detecto ninguno de los microorganismos ni VB. En 30 casos (15,1%) se evidencio VB. Las frecuencias de deteccion fueron: Ureaplasma urealyticum, 49,5%; Candida spp. 34,3%; Mycoplasma hominis, 14,1%; Streptococcus agalactie, 4,5%; Trichomonas vaginalis, 3,5%; Chlamydia trachomatis, 2,5%. No se detecto ningun caso de Neisseria gonorrhoeae. Conclusiones Se detecta una relevante prevalencia de Vaginosis bacteriana. LLama la atencion la baja circulacion de Trichomonas vaginalis, Chlamydia trachomatis y la ausencia de N. gonorrhoeae. La busqueda de Streptococcus agalactie (intraparto) y Chlamydia trachomatis (prenatal) debe extenderse a todas las embarazadas. El aislamiento, tipificacion y perfil de resistencia a farmacos de Candida spp. y la busqueda de Neisseria gonorrhoeae,Ureaplasma urealyticum y Mycoplasma hominis se debe acotar al expreso requerimiento clinico.

Partial Characterization of Temperature-Sensitive Mutants of Foot-and-Mouth Disease Virus, O1 Caseros Strain

The preliminary characterization of four temperature-sensitive (ts) mutants of the O1 Caseros strain of foot-and-mouth disease virus is described. Two mutants, ts 6 and ts 40, showed a very low RNA synthesis rate at nonpermissive temperature and were classified phenotypically as RNA(-). Shift-up experiments demonstrated an incapacity to organize the RNA replicative process at nonpermissive temperature. Another mutant (ts 139) behaved phenotypically as RNA(+) and its virions were more thermolabile than the wild type virus, so the defect in this mutant is likely to be in one of its structural proteins. Finally, mutant ts 5 was phenotypically RNA(+); its leak production at nonpermissive temperature was high, and the shift-up experiment showed a defect that was expressed either late in the replicative cycle or continuously.

Trends of syphilis in Posadas city (Misiones State, Argentina), 1997-2000

Objetivos: O estado de Misiones esta situado no noroeste argentino, nas fronteiras oeste e norte com o Brasil e a leste do Paraguai. Este foi o interesse para estabelecer a evolucao da sifilis na cidade de Posadas (300.000 habitantes), capital do estado de Misiones, desde 1997 ate 2000. Metodos: A sifilis foi analisada por meio da avaliacao epidemiologica, clinica e confirmacao laboratorial (VDRL e FTA- ABS). Todas as mulheres gravidas no momento da evolucao foram consultadas no hospital Madariaga, durante o periodo de abril a junho, de 1997 ate 2000 (n = 4700), as quais foram incluidas nas analises. Resultados: A frequencia da sifilis em mulheres gravidas atendidas em hospital publico foi de 2,1% (1997), 2,6% (1998), 4,6% (1999) e 3,7% (2000). A faixa etaria de maior vulnerabilidade foi de 15 a 19 anos. A distribuicao geografica de casos originados de quatro grupos isolados em 1997 expandiu-se para uma grande ocorrencia em todas as regioes de baixo nivel de vida socioeconomico (30% do total da populacao). A sifilis congenita chegou a uma media de 10,8 casos por 1.000 criancas nascidas vivas nos ultimos anos. Conclusao: A cidade de Posadas teve um aumento de sifilis em mulheres gravidas de 1997 ate 1999. Esta situacao endemica indica que o programa convencional STD-Aids teve um efeito minimo ou nulo sobre a pratica do sexo, principalmente em grupos de adolescentes. Um programa de intervencao do alvo geografico (visita casa por casa) direcionado para prover controle pre-natal como prioridade teve inicio em 1999. Uma estabilizacao da sifilis em mulheres gravidas foi demonstrada em 2000, mas a incidencia e ainda demasiadamente alta. Torna-se necessaria a discussao de um programa de extensao regional que inclua a populacao binacional das grandes areas povoadas.