Papers by Ferdinando Liprandi
Revista Científica de la Facultad de Ciencias Veterinarias de la Universidad del Zulia, 2000
Se evaluo la respuesta inmunitaria serotipo especifica contra rotavirus porcinos, en sueros de le... more Se evaluo la respuesta inmunitaria serotipo especifica contra rotavirus porcinos, en sueros de lechones y sueros hiperinmunes producidos en conejo, mediante un ELISA de competencia. El uso de una bateria de 6 anticuerpos monoclonales (AcM) producidos contra la proteina VP7 de los serotipos G3, G5 o G11 y un AcM contra el segmento VP8* de la proteina VP4 del serotipo P9, permitio la identificacion de tres grupos de reactividad. El primer grupo, representado por los AcM dirigidos a los serotipos G3 y G5, definido por el reconocimiento reciproco de los AcM 1C10 y 7D2 y, otro no reciproco por el AcM 1C3. El segundo grupo de reactividad formado por los AcM de serotipo porcino G11, definido por el reconocimiento reciproco de los AcM 6E10 y 8D10 y el no reciproco del AcM 5E6. El AcM 4B2, dirigido contra VP8*, represento el tercer grupo de reactividad. La respuesta inmunitaria en sueros hiperinmunes fue serotipo especifica y apoyo la presencia de un epitope comun sobre las VP7 G3 y G5 porcinas y de un dominio exclusivo sobre el serotipo G11 porcino. En lechones de 1 a 8 semanas de edad, se encontraron niveles considerables de anticuerpos que compitieron con el panel de AcM, sugiriendo que pudieran estar representados en el repertorio de anticuerpos que se producen por infeccion natural.
Journal of Clinical Microbiology, 1994
Two porcine rotavirus strains, C60 and C95, which had been previously shown to be reactive in an ... more Two porcine rotavirus strains, C60 and C95, which had been previously shown to be reactive in an enzyme-linked immunosorbent assay with serotype Gl-specific monoclonal antibodies, were classified as Gl by cross-neutralization tests and on the basis of the homology of the sequenced VP7 gene. This report confirms that porcine rotavirus strains with a Gl serotype occur in nature. Group A rotaviruses constitute the viral agent most commonly associated with acute diarrheal illness in piglets (8). Two surface proteins of group A rotaviruses, VP4 and VP7, associated with P and G serotype specificity, respectively, have been shown to independently elicit neutralizing antibodies and induce protective immunity (8). Among group A rotaviruses, 14 G serotypes have been identified in different species (4, 5, 8, 20). Rotavirus strains isolated from pigs have been assigned to G serotypes 3, 4, 5, and 11 (8); additional porcine strains with unique antigenic characteristics have been described but not fully characterized (2, 16, 18). Among these, a group of fecal samples and the respective cell-adapted strains, obtained from diarrheic piglets in Argentina, were shown to be reactive in a serotyping immunoassay with monoclonal antibodies specific for human serotype Gl or G2 (2). When studied in neutralization tests, one of these strains, C60, exhibited a reciprocal cross-reactivity with the human serotype 1 Wa strain and a one-way reactivity with the OSU strain (G5). Rotavirus strains of Gl specificity have been isolated worldwide from humans but not from other species, with the exception of one bovine isolate, strain T449, from Argentina (3). To establish in a definitive way that serotype Gl strains circulate among pigs, we retested two porcine strains, C60 and C95, by cross-neutralization and sequenced their respective genes coding for the serotype-specific glycoprotein (VP7). Both serology and sequence homology data show that the two strains have a Gl serotype specificity. Strains C60, C91, C95, and CN117 (kindly provided by R. Bellinzoni and N. Mattion, Centro de Virologia Animal, Capital Federal, Argentina) were propagated in MA104 cells in the presence of 1 ,ug of trypsin per ml and were further plaque purified three times before characterization. The electropherotypes of the four plaque-purified strains are shown in Fig. 1. The electropherotypes of strains C95 and C91 were identical, and strain CN117 differed from these strains in the mobility of at least gene 7, while strain C60
Revista Cientifica, Facultad de Ciencias Veterinarias, Universidad del Zulia, 2000
PubMed, 1986
Resumo: Se obtuvo por la técnica de hibridomas, un anticuerpo monoclonal (4B2D2) reactivo con el ... more Resumo: Se obtuvo por la técnica de hibridomas, un anticuerpo monoclonal (4B2D2) reactivo con el antígeno grupo común de la proteína más abundante de la cápside interna (45K) de rotavirus procino, cepa OSU. La eficiencia de este anticuerpo en la detección de ...
PubMed, Dec 1, 1993
Eight IgM monoclonal antibodies (mAbs) obtained from a Schistosoma mansoni chronically infected m... more Eight IgM monoclonal antibodies (mAbs) obtained from a Schistosoma mansoni chronically infected mouse immunized twice with adult worms butanolic extract (BE) and soluble egg antigen (SEA) were characterized by immunochemical methods. An intense cross-reactivity between different developmental stages was observed by indirect immunofluorescence assay (IIFA) with five anti-SEA mAbs. These mAbs appeared to recognize glycosidic residues, as suggested by 1) the inhibition of their reactivity by periodate oxidation of SEA, 2) the multiple polypeptide recognition in radioimmunoprecipitation and immunoblot assays and 3) reactivity with KLH. Anti-SEA mAbs were able to mediate in vitro killing of schistosomula but they were not consistently able to mediate passive transfer immunity in vivo. Three of anti-SEA mAbs were suitable for the performance of a sandwich ELISA for antibody detection in S. mansoni infected patients, allowing an increase in the signal to noise ratio as compared to the direct ELISA SEA method. Three anti-BE mAbs showed a more stage restricted pattern of antigen recognition by IIFA. Only one out of three seemed to be directed against glycan residues, but the other mAbs showed a plural pattern of polypeptide recognition on BE immunoblot, suggesting that repeated epitopic motifs are also present in different proteins within the same parasite developmental stage.
Journal of Virological Methods, Sep 1, 2006
The Ridascreen® Norwalk-like virus enzyme immunoassay was compared with (RT)-PCR on 92 stool samp... more The Ridascreen® Norwalk-like virus enzyme immunoassay was compared with (RT)-PCR on 92 stool samples collected from children with sporadic acute gastroenteritis. Homogenization and pre-dilution of the whole stool sample resulted in high specificity (97.5%) and moderate sensitivity (60%). This assay may be useful to screen outbreaks for norovirus, but limited to detect the virus in sporadic cases of diarrhea.
Tropical Medicine and Infectious Disease, Dec 21, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of General Virology, Oct 1, 1981
Two preparations of yellow fever vaccine (17D) were studied by clonal analysis. From one (17D-Eng... more Two preparations of yellow fever vaccine (17D) were studied by clonal analysis. From one (17D-England) three types of clones were isolated, each differentiated by plaque size in Vero cells and virulence for intracerebrally inoculated mice: small plaque (SP) and large plaque (LP) clones were lethal, whereas medium plaque (MP) clones failed to kill at doses up to 10 6 p.f.u. Analysis of 24 randomly selected clones showed the original vaccine to be a mixture of predominantly MP and SP variants; 58% and 42% respectively. A single passage in suckling mice modified this composition to 90% SP and 10% LP variants. The response of six inbred strains of mice to intracerebral inoculation of the MP variant varied from complete resistance to complete susceptibility. From another 17D substrain (17D-South Africa) two types of variants were isolated (a SP avirulent type and a LP type of intermediate virulence), both different from the previously described variant.
Journal of General Virology, Oct 14, 2009
Dengue virus (DENV) is the causative agent of dengue fever and the more severe forms of the infec... more Dengue virus (DENV) is the causative agent of dengue fever and the more severe forms of the infection known as dengue haemorrhagic fever and dengue shock syndrome (DHF/DSS). Secondary infections with a serotype different from the primary infection are considered a risk factor for the development of DHF/DSS. One explanation for the increased risk of DHF/DSS development after heterologous secondary infections is the antibody-dependent enhancement (ADE) hypothesis. This hypothesis postulates that pre-existing non-neutralizing antibodies will form immune complexes with the new serotype-infecting virus that in turn will have enhanced capacity to infect macrophages and other Fcc receptor (FccR)-bearing cells. Despite the evidence supporting the ADE hypothesis, the molecular mechanisms of ADE are not fully understood. In this work, we present evidence which indicates that intact lipid rafts are required for the ADE infection of U937 cells with DENV. Flow cytometry analysis to measure the percentage of infected cells showed that treatment of differentiated U937 cells with nystatin (30 mg ml "1), filipin (10 mg ml "1) or b-methyl cyclodextrin (30 mM) significantly reduces (P,0.05) the ADE of DENV-4 infection in vitro without any effect on viability or the number of FccR-bearing cells. Later cholesterol replenishment by supplementing treated cell cultures with bovine fetal serum for 24 h re-established lipid raft integrity and reversed the alteration of the ADE in vitro (P,0.05). Our results suggest that ADE of U937 infection by DENV requires the presence of cholesterol and cholesterol-rich membrane microdomains.
The humoral immune response against rotavirus in three gnotobiotic piglet sera and in 89 pig sera... more The humoral immune response against rotavirus in three gnotobiotic piglet sera and in 89 pig sera from different ages collected from different farms were studied by focus fluorescent neutralization assay (FFNA). The gnotobiotic piglets, infected with porcine rotavirus strain OSU (P9, G5) or Gottfried (P2B, G4), showed that humoral response is serotype-specific to the immunizing strain, besides being directed to both neutralization antigens, VP4 and VP7. On the other hand, the humoral response in piglets from any given farm was heterotypic (to porcine and no porcine strains) during the first 2 weeks of life. In animals, ranging from 3-8 weeks, prevalence of antibodies was lower to all porcine strains and was due to active infection.
Acta cientifica venezolana, 1986
Resumo: Se obtuvo por la técnica de hibridomas, un anticuerpo monoclonal (4B2D2) reactivo con el ... more Resumo: Se obtuvo por la técnica de hibridomas, un anticuerpo monoclonal (4B2D2) reactivo con el antígeno grupo común de la proteína más abundante de la cápside interna (45K) de rotavirus procino, cepa OSU. La eficiencia de este anticuerpo en la detección de ...
PubMed, 1992
Hepatitis B virus surface antigen (HBsAg) found in a commercial vaccine was use as immunogen and ... more Hepatitis B virus surface antigen (HBsAg) found in a commercial vaccine was use as immunogen and antigen for the production and selection of murine monoclonal antibodies against this viral antigen. Antibody relative avidity was determined based on their capture capacity. Competition studies, and the differential recognition pattern of vaccine preparations showed that high avidity IgG1 antibodies were directed against two distinct antigenic regions. Among them, 6F4 was most suitable for the detection of HBsAg in a sandwich ELISA system, using an IgM antibody, 5E8, as capture. However, the combined use of 6F4 with another which does not recognize the same epitope did not improve the sensitivity of the assay. On the other hand, the combination of 6F4 with a lower avidity IgG1 antibody, 6G10, increased the universe of antigenic diversities recognized by this system. An enzyme immunoassay for detection of HBsAg is proposed, using 3 monoclonal antibodies: one IgM as capture and two IgG1 for detection.
Investigación Clínica
By the end of 2021, the Omicron variant of SARS-CoV-2, the coronavirus responsible for COVID-19, ... more By the end of 2021, the Omicron variant of SARS-CoV-2, the coronavirus responsible for COVID-19, emerges, causing immediate concern, due to the explosive increase in cases in South Africa and a large number of mutations. This study describes the characteristic mutations of the Omicron variant in the Spike protein, and the behavior of the successive epidemic waves associated to the sub-lineages throughout the world. The mutations in the Spike protein described are related to the virus ability to evade the protec-tion elicited by current vaccines, as well as with possible reduced susceptibil-ity to host proteases for priming of the fusion process, and how this might be related to changes in tropism, a replication enhanced in nasal epithelial cells, and reduced in pulmonary tissue; traits probably associated with the apparent reduced severity of Omicron compared to other variants.
Salus, 2022
Introducción: El agente etiológico responsable de COVID-19, SARSCoV-2, es un virus ARN pertenecie... more Introducción: El agente etiológico responsable de COVID-19, SARSCoV-2, es un virus ARN perteneciente a la familia Coronaviridae. Durante la replicación, los componentes virales interactúan con la maquinaria celular induciendo alteraciones en la fisiología celular, lo que contribuye a la patogénesis del virus. Método: Revisión bibliográfica en NCBI/Pubmed sobre estrés celular y SARS-CoV-2 Hallazgos de interpretación: Como respuesta a la infección, en la célula hospedadora se activan vías de señalización, cuyo principal objetivo es recuperar la homeostasis y de no lograrlo, inducir a la activación de la muerte celular. Entre las vías de señalización mejor caracterizadas, destacan las rutas de estrés celular como el estrés oxidativo, la UPR (Respuesta a proteínas no plegadas), y la autofagia, las cuales son evolutivamente bien conservadas y además están interconectadas entre sí. Hay fuerte evidencia teórica y experimental de diversas interacciones de algunos componentes de estas rutas ...
Intervirology, 2020
Background: The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its... more Background: The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its disease COVID-19 has strongly encouraged the search for antiviral compounds. Most of the evaluated drugs against SARS-CoV-2 derive from drug repurposing of Food and Drug Administration-approved molecules. These drugs have as target three major processes: (1) early stages of virus-cell interaction, (2) viral proteases, and (3) the viral RNA-dependent RNA polymerase. Summary: This review focused on the basic principles of virology and pharmacology to understand the importance of early stages of virus-cell interaction as therapeutic targets and other main processes vital for SARS-CoV-2 replication. Furthermore, we focused on describing the main targets associated with SARS-CoV-2 antiviral therapy and the rationale of drug combinations for efficiently suppressing viral replication. Key Messages: We hypothesized that blocking of both entry mechanisms could allow a more effective antiviral e...
Journal of Virology, 1996
It has been previously shown that rotavirus maturation and stability of the outer capsid are calc... more It has been previously shown that rotavirus maturation and stability of the outer capsid are calcium-dependent processes. More recently, it has been hypothesized that penetration of the cell membrane is also affected by conformational changes of the capsid induced by Ca2+. In this study, we determined quantitatively the critical concentration of calcium ion that leads to solubilization of the outer capsid proteins VP4 and VP7. Since this critical concentration is below or close to trace levels of Ca2+, we have used buffered solutions based on ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and Ca-EGTA. This method allowed us to show a very high variability of the free [Ca2+] needed to stabilize, at room temperature, the outer capsid of several rotavirus strains. This concentration is about 600 nM for the two bovine strains tested (RF and UK), 100 nM for the porcine strain OSU, and only 10 to 20 nM for the simian strain SA11. Titration of viral in...
Travel Medicine and Infectious Disease, Jul 1, 2022
Background By the end of 2021, the SARS-CoV-2 Variant of Concern (VOC) Delta was predominant in m... more Background By the end of 2021, the SARS-CoV-2 Variant of Concern (VOC) Delta was predominant in most of the world. At the end of November, the Omicron variant was first detected in South Africa. This variant was immediately classified as VOC, due to the explosive increase of cases in South Africa, and the great number of mutations exhibited by this new lineage. Since then, Omicron VOC displaced Delta one in almost every country. Venezuela implemented in May 2021 molecular testing of all the passengers arriving at Venezuelan airports. Methods In this study, we analyzed the presence of variants of SARS-CoV-2 in those positive samples, by sequencing a small fragment of the Spike genomic region. Results The Omicron variant was found in passengers arriving to Venezuela from the beginning of December. Complete genome analysis confirmed the presence of the Omicron VOC. The detection of this VOC coincided with an unprecedented increase in the frequency of passengers with positive nucleic acid testing. Conclusions Genomic surveillance of samples for international travelers returning to Venezuela allowed us to rapidly detect the introduction of the Omicron variant in the country.
Archives of Virology, Dec 1, 1976
Research in Virology, Jul 1, 1997
Identification of bovine rotaviruses in Venezuela : antigenic and molecular characterization of a... more Identification of bovine rotaviruses in Venezuela : antigenic and molecular characterization of a bovine rotavirus strain M. Ciarlet (I) (*), C.I. Pifia (I), 0. Garcia (I* ') and F. Liprandi (')
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Papers by Ferdinando Liprandi