Fundamentos moleculares de la exclusión competitiva durante la coinfección de virus respiratorios: a propósito del COVID-19 / Molecular foundations of competitive exclusion during coinfection of respiratory viruses: about COVID-19

Introducción: La idea de exclusión competitiva es indiscutible cuando se trata de animales y bacterias que intentan ocupar el mismo nicho ecológico, pero su aplicación a la coinfección viral no es tan sencilla de interpretar. La interferencia viral es un fenómeno en el que un virus suprime competitivamente la replicación de otros virus coinfectantes y es el resultado más común de las coinfecciones virales. Objetivo: Comprender mejor el comportamiento de las infecciones respiratorias concomitantes en escenarios de brotes comunitarios y de forma individual en entornos hospitalarios e individuos con comorbilidades. Métodos: Se realizó una búsqueda de información en las bases de datos MEDLINE / PubMed, SciELO y LILACS. También se consideraron artículos publicados en el repositorio de preimpresión medRxiv y los informes de los Centros para el Control y Prevención de enfermedades de los Estados Unidos de América. Mediante el gestor de referencias Mendeley, se eliminaron los duplicados y aquellos que no se ajustaban al objetivo del estudio, seleccionando 48 artículos para la revisión. Análisis y síntesis de la in formación: En la literatura científica se encontró evidencia que sustenta la exclusión competitiva viral entre virus relacionados que comparten células susceptibles y permisivas. Conclusión: La exclusión competitiva impide que dos virus que comparten rutas de transmisión similares y el mismo órgano diana, infecten no sólo al mismo tiempo, sino que también se propaguen con éxito. Por lo tanto, la sindemia producida por virus que comparten estas características podría ser un evento improbable(AU)

Introduction: The idea of competitive exclusion is undisputed when it comes to animals and bacteria trying to occupy the same ecological niche, but its application to viral coinfection is not so simple to interpret. Viral interference is a phenomenon in which one virus competitively suppresses the replication of other co-infecting viruses and is the most common outcome of viral co-infections. Objective: To better understand the behavior of concomitant respiratory infections in community outbreak settings and individually in hospital settings and individuals with comorbidities. Methods: A search for information was performed in the MEDLINE / PubMed, SciELO and LILACS databases. Articles published in the preprint repository medRxiv and reports from the US Centers for Disease Control and Prevention were also considered. Using the Mendeley reference manager, duplicates and those that did not fit the study objective were eliminated, selecting 48 articles for the review. Analysis and synthesis of information: Evidence supporting viral competitive exclusion between related viruses sharing susceptible and permissive cells was found in the scientific literature. Conclusion: Competitive exclusion prevents two viruses that share similar transmission routes and the same target organ from infecting not only at the same time, but also from spreading successfully. Therefore, syndemia produced by viruses sharing these characteristics could be an unlikely event(AU)

Commentory on “LIVE, ORALLY GIVEN POLIOVIRUS VACCINE - EFFECTS OF RAPID MASS IMMUNIZATION IN POPULATION UNDER CONDITIONS OF MASSIVE ENTERIC INFECTION WITH OTHER VIRUSES.

The following is a commentary on the article “Sabin AB, Ramos-Alvarez M, Alvarez-Amezquita J, Pelon W, Michaels RH, Spigland I, et al. Live, orally given poliovirus vaccine: effects of rapid mass immunization on population under conditions of massive enteric infection with other viruses. Jama. 1960;173(14):1521-6.” Abstract (of the original article): The phenomenon of viral interference must be taken into account in planning the use of live poliovirus vaccine in areas where conditions favor the extensive dissemination of naturally occurring polioviruses. Experience with feeding a trivalent vaccine to 26,033 children in a tropical city of 100, 000 population led to the conclusion that interference was overcome by mass feeding of vaccine to 86% of all children under 11 years within a period of about four days, and that, because dissemination of the poliovirus was self-limited, a second feeding of trivalent vaccine was necessary to achieve immunization of almost all children. Recom-mendations are here formulated for the eradication of poliomyelitis, but they apply only to subtropical and tropical regions with extensive dissemination of various enteric viruses and not to temperate zones with good sanitation and hygiene during certain periods of the year and under conditions of low or absent dis-semination of enteric viruses.

Interacción entre el virus de la inmunodeficiencia humana y el virus GB tipo-C durante el estado de co-infección / Interaction between HIV-1 and GB virus type-C during coinfection status

The human immunodeficiency virus (HIV) infection is one of the most important problems in public health. It is estimated that 3 3 million people are infected around the world. HIV and GBV-C share the same transmission route, being frequent the co-infection. Since both viruses replicate in CD4+ lymphocytes, recent studies have described an interaction. Decreasing of HIV viral load and higher CD4 counts have been observed in co-infected patients, leading a better clinical outcome. Nevertheless, some epidemiological studies have shown contradictory results. Additionally, in vitro models report inhibition of HIV by E1, E2, NS3 and NS5A GBV-C proteins, resulting in a decreasing of p24 antigen. This review summarizes the principal findings about co-infection and mechanisms that have been proposed for HIV-1 inhibition.

La infección por el virus de la inmunodeficiencia humana (VIH) continúa siendo uno de los principales problemas en salud pública; se estima que existen actualmente más de 33 millones de personas infectadas en el mundo. El VIH y el virus GB tipo C (GBV-C) comparten la misma vía de transmisión, por lo que es frecuente encontrar individuos co-infectados. Estudios recientes han descrito un efecto inhibitorio asociado a disminución en la carga viral de VIH, altos recuentos de CD4 y mayor tiempo de sobrevida en pacientes co-infectados, resultando en un mejor pronóstico y menor progreso a SIDA; adicionalmente, estudios in vitro indican que las proteínas virales E1, E2, NS3 y NS5A del GBV-C estarían implicadas en la inhibición del VIH-1. En el presente artículo se revisan los principales aspectos de la co-infección, y se describen los mecanismos propuestos para la inhibición de la replicación del VIH-1 mediada por las proteínas virales del GBV-C.

A practical approach to the understanding and teaching of RNA silencing in plants

Gene silencing, also called RNA interference (RNAi) is a specific mechanism of RNA degradation involved in gene regulation, development and defense in eukaryotic organisms. It became an important subject in the teaching programs of molecular biology, genetics and biotechnology courses in the last years. The aim of this work is to provide simple and inexpensive assays to understand and teach gene silencing using plants as model systems. The use of transient and permanent transgenic plants for expressing reporter genes, like those derived from jellyfish green fluorescent protein (gfp) encoding gene, provides a nice, colorful and conclusive image of gene silencing. Three experimental approaches to evidence RNA silencing are depicted. In the first approach gene silencing is demonstrated after transient expression of reporter genes in non-transgenic plants. In the second, silencing is triggered against a reporter gene stably integrated into a transgenic plant. The third approach involves the triggering of RNA silencing against endogenous genes using viral vectors. In addition we illustrate systemic gene silencing showing how the silencing signal is spread over a plant and finally it is also demonstrated the suppression of gene silencing. The first group of experiments is recommended to be tough on undergraduate courses, the following two sections are recommended for graduate courses. Hopefully, it will help students to understand this important phenomenon and to unravel the importance of gene silencing as a key gene regulation mechanism and as a molecular and biotechnological tool.

Is the anti-sarcoma and anti-viral cytokine "plasma factor" a novel chicken Y-box protein?

A line of research beginning in the early 1960s with the observation that West Nile virus and, later, several strains of rabies virus could inhibit the development of the Rous sarcoma virus-induced tumor in the wing-web of chicken (a "sarcoma-blockade") eventually culminated in the characterization of a 14-kDa circulating anti-sarcoma and anti-viral activity christened "plasma factor" (PF) which, unlike the interferons, inhibited the replication of diverse RNA-containing viruses, but not of any DNA-containing viruses. The possibility that this 14 kDa protein represented a novel antiviral cytokine has been strengthened by analysis of partial amino acid sequencing data which suggest that this 14-kDa cytokine may correspond to the 127-amino acid-long chicken YB2-like protein (Locus: XP_423576) deduced very recently from the genomic sequencing of chicken. Biologically, proteins of the Y-box family (such as chicken YB1 and YB2) not only bind DNA and thus regulate transcription but also bind single-stranded RNA in a sequence-specific and reversible manner, repress viral RNA translation, inhibit retroviral transformation of chicken fibroblasts, and are known to regulate transcription of human immunodeficiency virus and hepatitis B virus. Taken together, the available data point to a novel anti-viral cytokine with a novel mechanism of action.

Níveis de anticorpos contra a doença de Newcastle mediante a imunização com vacinas associadas com os vírus da bronquite infecciosa e da infecção da bursa de Fabrícius / Levels of antibodies against Newcastle disease by immunization wuith associated vaccines with infectious bronchitis virus and infectiuos bursal disease

Um artifício atualmente bastante difundido para a imunização de aves em apenas uma única administração, seria a utilização de vacinas associadas; mas segundo alguns pesquisadores, frangos de corte vacinados com vacinas associadas contendo vírus vivos atenuados da doença de Newcastle (DNC) e da bronquite infecciosa das galinhas (BIG), podem sofrer um fenômeno denominado interferência viral, incapacitando o sistema imunológico de estimular a produção de anticorpos (AC) protetores, produzindo uma competição por epítopos, ou dirigindo a resposta imune em outros sentidos. Estes animais foram divididos em nove tratamentos e imunizados com vacinas contendo as cepas HB1 (HB1 e Clone 30) do vírus da DNC e da cepa Massachusetts (H120 e Ma5) para o vírus da BIG, em diversas combinações, administradas pela via ocular. Um tratamento (T11) deixado sem imunização foi utilizado como controle. Os tratamentos T2, T4 e T10 sofreram imunização apenas contra a DNC em separado ou associada no momento da vacinação ou em laboratório à BIG, sendo que nos tratamentos T5, T6, T7, T8 e T9 foi incluída a vacinação contra a infecção da bursa de fabrícius (IBF). Os resultados mostram haver uma redução na produção de AC contra a DNC quando esta foi associada à BIG (tratamento 4), ambas doluídas no mesmo frasco no momento da vacinação. Porém observou-se menor interferência, a partir da utilização de uma vacina já associada em laboratório (tratamento 10). Quanto à presença do vírus da IBF presente nos grupos G5 a G8, este parece favorecer o sistema imune através de um estímulo precoce deste, reduzindo a diferença na qualidade de AC quando estas são posteriormente associadas.

Circulación silenciosa de poliovirus demostrada por interferencia a los enterovirus no polio / Silent circulation of poliovirus demonstrated by interference against non-polio enterovirus

Se obtuvieron muestras de heces semanalmente, en niños menores de 3 años para aislar los poliovirus y enterovirus no polio, con el objetivo de incrementar el conocimiento de las circulaciones de los derivados de la vacuna durante las campañas masivas. Los esquemas de vacunación continua permiten la circulación de esos virus durante grandes períodos de tiempo. En los niños se demostró una interferencia de los enterovirus no polio por los poliovirus vacunales. Sin embargo, mientras los bajos porcentajes de enterovirus no polio no mostraron diferencias significativas, sí se encontró en los altos porcentajes de poliovirus vacunales aislados en niños menores de 1 año en relación con los de 1 y 2 años. Basados en esa contradicción, se estimó la circulación silenciosa de los poliovirus por cálculos matemáticos. Con los poliovirus estimados se permitió obtener las curvas simuladas. Posteriormente, en otra investigación se confirmaron los resultados por métodos inmunológicos

Occurrence and cross infectivity of granulovirus of field bean pod borer Adisura atkinsoni Moore.

A granulovirus (GV) was isolated from the field-bean pod borer, Adisura atkinsoni. Electron microscopic observation showed capsule or granular shaped occlusion bodies. The virus was highly virulent against second instar larvae when tested at 1 x 10(6) occlusions/larva through food surface (pod/seed) contamination technique. The incubation period ranged from 6-10 days in the case of second instar larvae. In contrast to green coloured healthy larvae. GV infected A. atkinsoni became brownish/pale white in colour mostly due to accumulation of large number of occlusion bodies. Study on the cross infectivity of A. atkinsoni GV to gram caterpillar, Helicoverpa armigera revealed the high susceptibility of H. armigera to A. atkinsoni GV, thereby widening the scope of controlling both the species on the same cropping system. This is the first record of GV from A. atkinsoni from India.

In vivo down regulation of HIV replication after hepatitis C superinfection

There are increasing molecular and clinical evidences that the effects of human immunodeficiency virus (HIV) infection can be modified by coinfection with other viruses. The objective was to investigate the viral interaction between HIV and hepatitis C virus (HCV) after HCV superinfection. A 16 year-old pregnant woman was evaluated because of icteric acute hepatitis. Admission laboratory tests showed the following results: ALT 877 IU/L; AST 1822 1822 IU/L; bilirubin 6.79 mg/dl. Diagnosis of acute HCV was based on detection of serum HCV RNA by PCR and anti-HCV seroconversion. ELISA for anti HIV testing was positive and confirmed by western blot. Serum markers for other viruses were negative. The patient was followed during 19 months; serum samples were taken monthly during this period for detection of plasma HIV and HCV RNA. Levels of plasma HIV-RNA were positive in all samples ttested before and after the onset of acute hepatitis C. Six months later and a for two month period, and 13 months later for a period of one month HIV viremia was undetectable; then HIV-RNA in plasma was detectable again. In conclusion, HCV superinfection may have temporarily interfered with HIV replication in our patient. The following observations support our hypothesis: it has been demonstrated that HIV-1 replication is suppressed by HCV core protein which has transcriptional regulation properties of several viral and cellular promoters. Clinical implications of this event are not generally known and the interaction between these two viruses in dual infections is worth considering.

Interferência entre as vacinas anti-sarampo e antipoliomielite / Interference between measles and polio vaccines

O objetivo da presente pesquisa foi avaliar se a administraçäo prévia de vacina oral antipoliomielite, tipo Sabin (VOP-Sabin), interfere na eficácia sorológica da vacina do sarampo. Com essa finalidade estudaram-se 117 crianças, de nove meses de idade, que receberam vacina de vírus vivo atenuado do sarampo (cep BIKEN CAM 70) no período de quatro semanas, ou menos, após terem recebido vacina oral antipoliomielite (VOP-Sabin), e 88 crianças, da mesma faixa etária mas sem vacinaçäo recente com a VOP-Sabin, como controle. Os anticorpos IgG para o sarampo foram pesquisados mediante a reaçäo de imunofluorescência indireta. A proporçäo de soroconversäo para a vacina do sarampo foi de 19/23 (82,6%) nas crianças que tinham recebido a VOP-Sabin 2 a 6 dias antes; 29/37 (78,4%), nas que receberam VOP-Sabin 9 a 13 dias antes; 32/42 (76,2%), nas vacinadas com a VOP-Sabin 16 a 20 dias antes; e 12/15 (80,0%), nas vacinadas com intervalos de 23 a 26 dias. A proporçäo de soroconversäo no grupo controle (vacinadas quatro semanas ou mais após a VOP-Sabin) foi de 68/88 (77,8%) e a comparaçäo destas proporçöes näo mostrou diferenças estatisticamente significativas. Os resultados obtidos näo demonstraram, portanto, uma menor eficácia sorológica para a vacina do sarampo em crianças previamente vacinadas contra a pólio que recebram a vacina Sabin durante as quatro semanas anteriores

Dengue virus vaccina studies in Puerto Rico: a review

Esta publicación resume los trabajos de investigación efectuados con vacunas de virus de dengue por los Laboratorios de Virología de la Escuela de Medicina de la Universidad de Puerto Rico. La inmunogenicidad y la atenuación de estas vacunas, enviadas por el Instituto de Investigación Walter Reed, fueron respectivamente estudiadas en monos rhesus (Maccaca mulatta) en mosquitos (Toxorynchites amboinensis). Este modelo experimental demostró que de seis vacunas, sólo dos (DEN-2/S-1 y la cepa 341750 de dengue 4) ameritan nuevos estudios evaluativos. Estos y otros estudios serán necesarios para la obtención de vacunas efectivas para prevenir el dengue y sus manifestaciones hemorrágicas