Comparative analysis of SARS-CoV-2 variants Alpha (B.1.1.7), Gamma (P.1), Zeta (P.2) and Delta (B.1.617.2) in Vero-E6 cells: ultrastructural characterization of cytopathology and replication kinetics

Abstract This study compares the effects of virus-cell interactions among SARS-CoV-2 variants of concern (VOCs) isolated in Brazil in 2021, hypothesizing a correlation between cellular alterations and mortality and between viral load and transmissibility. For this purpose, reference isolates of Alpha, Gamma, Zeta, and Delta variants were inoculated into monolayers of Vero-E6 cells. Viral RNA was quantified in cell supernatants by RT‒PCR, and infected cells were analyzed by Transmission Electron Microscopy (TEM) for qualitative and quantitative evaluation of cellular changes 24, 48, and 72 hours postinfection (hpi). Ultrastructural analyses showed that all variants of SARS-CoV-2 altered the structure and function of mitochondria, nucleus, and rough endoplasmic reticulum of cells. Monolayers infected with the Delta variant showed the highest number of modified cells and the greatest statistically significant differences compared to those of other variants. Viral particles were observed in the cytosol and the cell membrane in 100 % of the cells at 48 hpi. Alpha showed the highest mean particle diameter (79 nm), and Gamma and Delta were the smallest (75 nm). Alpha and Gamma had the highest particle frequency per field at 48 hpi, while the same was observed for Zeta and Delta at 72 hpi and 24 hpi, respectively. The cycle threshold of viral RNA varied among the target protein, VOC, and time of infection. The findings presented here demonstrate that all four VOCs evaluated caused ultrastructural changes in Vero-E6 cells, which were more prominent when infection occured with the Delta variant.

Primer aislamiento y caracterización de la cepa prototipo del virus SARS-CoV-2 a inicios de la pandemia de la COVID-19 en el Perú

Introducción: Actualmente los contagios por el virus del SARS-CoV-2 supera los 600 millones de casos en el mundo. Objetivo: Aislar y caracterizar el virus SARS-CoV-2 causante de la COVID-19 a inicios de la pandemia en el Perú. Materiales y métodos: Se realizó el aislamiento viral a partir de 20 muestras de hisopado nasal y faríngeo positivas a SARS-CoV-2 por RT-PCR. El aislamiento se realizó en las líneas celulares Vero ATCC CCL-81 y Vero E6, evaluando el efecto citopático, la presencia del virus por RT-PCR, inmunofluorescencia indirecta (IFI) y posterior identificación por secuenciación genómica. Posteriormente, uno de los aislamientos de mayor circulación fue seleccionado y denominado cepa prototipo (PE/B.1.1/28549/2020), realizándose 10 pasajes sucesivos en células Vero ATCC CCL-81 para evaluar la dinámica de mutaciones. Resultados: Se observaron 11 aislamientos de virus por efecto citopático confirmándose por RT-PCR e IFI, de los cuales 6 fueron secuenciados identificándose los linajes B.1, B.1.1, B.1.1.1 y B.1.205, según el comité Pango de los genomas. La cepa prototipo corresponde a la variante B.1.1 y el análisis de las secuencias de los pasajes sucesivos mostró mutaciones a nivel de la proteína de la espiga (S) del virus, sin variación en la identidad del linaje. Conclusiones: Se aislaron 4 linajes en la línea celular Vero ATCC CCL-81. Los subcultivos en la misma línea celular muestran mutaciones en la proteína de la espiga, lo que indica mayor adaptabilidad a la célula hospedera y variación de la patogenicidad in vitro, comportamiento que le permite tener más éxito de supervivencia.

Introduction: Currently, infections caused by the SARS-CoV-2 virus exceed 600 million cases in the world. Objective: Isolation and characterization of the SARS-CoV-2 virus causing COVID-19 at the beginning of the pandemic in Peru. Materials and methods: Twenty nasal and pharyngeal swab samples were isolated from SARS-CoV-2 using two cell lines, Vero ATCC CCL-81 and Vero E-6; virus identification was performed by RT-PCR and the onset of cytopathic effect (CPE) was evaluated by indirect immunofluorescence and subsequent identification by genomic sequencing. One of the most widely circulating isolates were selected and named the prototype strain (PE/B.1.1/28549/2020). Then 10 successive passages were performed on Vero ATCC CCL-81 cells to assess mutation dynamics. Results: We detected 11 virus isolates by cytopathic effect, and subsequently confirmed by RT-PCR and indirect immunofluorescence. Of these, six were sequenced and identified as the lineages B.1, B.1.1, B.1.1.1, and B.1.205 according to the Pango lineage nomenclature. The prototype strain corresponded to lineage B.1.1. The analysis of the strains from the successive passages showed mutations mainly at in the spike (S) protein of the virus without variation in the identity of the lineage. Conclusions: Four lineages were isolated in the Vero ATCC CCL-81 cell line. Subcultures in the same cell line show mutations in the spike protein indicating greater adaptability to the host cell and variation in pathogenicity in vitro, a behavior that allows it to have more survival success.

Safety and immunogenicity of pre-exposure prophylaxis of approved freeze-dried rabies vaccine(Vero cell) for human use in adults ≥18 years of age / 中国生物制品学杂志

@#Objective To evaluate the safety and immunogenicity of pre-exposure prophylaxis of the approved freeze-dried rabies vaccine(Vero cell)(rabies vaccine in brief)for human use in adults ≥18 years of age.Methods Participants aged ≥18 years in Guizhou and Shanxi provinces from June 2022 to September 2022 were enrolled,vaccinated with 1 dose of rabies vaccine at 0,7,28 d respectively,and collected for 5. 0 mL of venous blood before the first dose and 14 d after the third dose. Immunofluorescence foci assay was used to detect rabies virus neutralizing antibodies,and adverse events were collected 0～7 d after each dose of vaccine.Results A total of 120 participants were enrolled,120 participants received the first dose of rabies vaccine,119 participants received the second dose and 118 participants received the third dose.Before the first dose of rabies vaccine,the seropositive rate of antibody was 2. 54% and the geometric mean concentration(GMC)was 0. 40 IU/mL. After the third dose of rabies vaccine,the seropositive rate and seroconversion rate were 100%,the GMC was 9. 68 IU/mL,and the geometric mean increase(GMI)was 23. 99. The incidence of adverse events 0～7 d after the first,second and third doses of rabies vaccine were 22. 50%,13. 45% and 4. 24%,respectively. The local adverse events were mainly pain,and the systemic adverse events were mainly fever,fatigue/weakness,dizziness,joint pain,and diarrhea.Conclusion Approved rabies vaccine showed good safety and immunogenicity in pre-exposure prophylaxis of people ≥ 18 years old.

Development and verification of a quantitative real-time PCR method for determination of host cell DNA residues in inactivated SARS-CoV-2 vaccine(Vero cells) / 中国生物制品学杂志

@#Objective To develop and verify a quantitative real-time PCR method for determination of the content of host cell DNA residues in severe acute respiratory symptom coronavirus 2(SARS-CoV-2) inactivated vaccine(Vero cells),in order to better control the safety of products.Methods DNA was extracted from inactivated SARS-CoV-2 vaccine(Vero cells) bulk by magnetic bead separation method,and the DNA residues of host cells were quantitatively analyzed by probetype PCR.The linear range,repeatability,intermediate precision,quantitative limit,specificity,durability and accuracy of the developed method were verified,and the host cell DNA re sidues of 5 batches of inactivated SARS-CoV-2 vaccine(Vero cells)were determined by this method.Results DNA standard curve showed good linearity in the range of 300～0.003 pg/μL(each R~2> 0.99);Relative standard deviations(RSD) of repeatability and intermediate precision verification were less than 20%;The quantitative limit was 0.001 pg/μL;Sample dilution and purified liquid dilution had no interference to detection;The results of 60 min incubation at 53,55,57 ℃ and 56,60,64 min incubation at 55 ℃ showed no significant difference;The recoveries of accuracy verification were 79%～83%,RSD <5%.This method had good adaptability in detecting DNA residues in the bulk of inactivated SARS-CoV-2 vaccine(Vero cells).Conclusion The quantitative realtime PCR method for determination of host cell DNA residues in inactivated SARS-CoV-2 vaccine(Vero cells) has been successfully developed,of which the linearity and range,repeatability,intermediate precision,quantitative limit,specificity,durability and accuracy meet the acceptable standards,and are suitable for the detection and quality control of host cell DNA residues in inactivated SARS-CoV-2 vaccine(Vero cells).

Development and verification of qPCR method for detection of residual host DNA in human rabies vaccine(Vero cells) / 中国生物制品学杂志

@#Objective To develop and verify a qPCR method for the qualitative and quantitative analysis of residual host DNA in human rabies vaccine(Vero cells) stock solution.Methods The qPCR standard curve was established by using the Vero cell DNA quantitative national standard,and the residual host DNA was extracted using magnetic beads.The specificity,repeatability,intermediate precision,accuracy and durability of the method were verified,and the linear range and limit of quantification were determined.The residual DNA of three batches of human rabies vaccine(Vero cells) stock solution was quantitatively analyzed and the fragment size was qualitatively analyzed by using this method.Results The correlation coefficients(R~2) of Vero cell DNA quantitative national standard amplification standard curve were all more than 0.99 by qPCR,and the quantitative range was 0.3 pg/mL～30 ng/mL.The method showed good specificity and repeatability.In the verification of intermediate precision,accuracy and durability,the relative standard deviations(RSD)of detection results of the samples were all less than 10%.The residual DNA content of Vero cells in three batches of stock solution was 0.20～0.77 ng/dose,which met the relevant standard of Chinese Pharmacopoeia(Volume Ⅲ,2020edition).The residual DNA fragments greater than 154 bp accounted for 52%～63%.Conclusion The developed qPCR method for the detection of residual DNA in human rabies vaccine(Vero cells) stock solution had good specificity,repeatability,intermediate precision and durability,and qualitatively and quantitatively analyzed the residual DNA rapidly and accurately,which was of great significance for improving the detection and control of residual DNA content in the production process and final product of human rabies vaccine(Vero cells).

Optimization of culture conditions of SARS-CoV-2 four Omicron variants in Vero cells / 中国生物制品学杂志

@#Objective To optimize the culture conditions of four vaccine candidates of severe acute respiratory symptom coronavirus 2(SARS-CoV-2) Omicron variants BA.1,BA.1.1,BA.2 and BA.5 in Vero cells.Methods The harvest time(24,48,72 and 96 h) and MOI(0.01,0.001,0.0001 and 0.000 01) of four Omicron variants cultured in Vero cells were optimized by using cytopathic effect(CPE),viral nucleic acid copy number and viral titer as evaluation indexes.Results The optimum harvest time of the four Omicron variants BA.1,BA.1.1,BA.2 and BA.5 in Vero cells was 72 h,and the optimum MOI was 0.001～0.000 01,0.001～0.000 01,0.01～0.000 01 and 0.01～0.000 01,respectively.Conclusion The culture conditions of four Omicron variants in Vero cells were optimized,which laid a foundation of the development of SARS-CoV-2 Omicron variant inactivated vaccine based on Vero cells.

Long-term infection passaging of Human Adenovirus 36 in monkey kidney cells

ABSTRACT Human Adenovirus 36 (HAdV-36) has been related to diverse effects on metabolism and may attenuate the lipid accumulation in kidneys with increased adiposity. Some of these effects would be related to viral persistence. However, until now, a model of persistent in vitro infection by HAdV-36 is unknown. In this study, we examined the cells of the Vero lineage to explore their permissiveness to long-term HAdV-36 infection. HAdV-36 was productively replicated in Vero cells and maintained long-term infection for up to 35 cell passages. A subculture was obtained from the cells that survived the primary infection at a low MOI (0.5). The production of the extracellular infectious virus with titers ranging from 104 to 106 TCID50/mL and DNA-bearing cells was detected. In long-term infected cells, the intracellular distribution of viral antigen was demonstrated by performing immunolocalization (IFI) and expression of cell-viral antigen in 50% of cells by flow cytometry, using anti-HAdV-36 hyperimmune rabbit serum. Furthermore, E1a and E4orf1 genes in long-term infected passages showed a decreasing trend. Our preliminary results reveal that renal epithelial monkey cells are permissive for the productive infection of HAdV-36. Vero cell culture long-term infection might be a promising model for addressing the fundamental aspects of the HAdV-36 biology that cannot reveal broadly-used cultures, which do not maintain long-term infection in primary or transformed cells.

Isolation and identification of a severe acute respiratory syndrome coronavirus 2 strain in feces from COVID-19 patients in Shanghai / 上海预防医学

ObjectiveTo isolate and study the biological characteristics of severe acute respiratory syndrome coronavirus 2 （SARS-CoV-2） from feces of coronavirus disease 2019 （COVID-19） patients. MethodsVero E6 cells were used for virus isolation and the isolated strains were tested by nucleic acid test， immunofluorescence test， virulence test and whole genome sequencing. 50% tissue culture infective dose （TCID50） was calculated after the cell cultures of each generation were collected ResultsEight fecal specimens were inoculated with Vero E6 cells after treatment and cultured for 48 h. One specimen showed obvious cytopathic effect on Vero E6 cells. One SARS-CoV-2 out of 8 fecal samples from COVID-19 patients were isolated， and separation rate was 12.5%. The TCID50 of P1， P2 and P3 were 104.0/0.2 mL， 104.5/0.2 mL and 104.75/0.2 mL， respectively. Only one of the 8 stool samples had SARS-CoV-2 virus replication and amplification， and the Ct value of the nucleic acid detection was about 10. The sequence of the isolation was more than 99.99% homologous with that of Wuhan-Hu-1（GenBank MN908947）. ConclusionThe SARS-CoV-2 strain is isolated from the fecal samples of COVID-19 cases and is confirmed by genomic sequencing and immunofluorescence test， which indicates the presence of live virus in feces of COVID-19 cases.

Establishment and evaluation of a fluorescent antibody assay against varicella-zoster virus membrane antigen based on Vero E6 cells / 中国输血杂志

【Objective】 To establish and evaluate a fluorescent antibody to membrane antigen (FAMA) method for detecting antibodies against varicella-zoster virus (VZV) based on Vero E6 cells. 【Methods】 Based on the adapted VZV-Oka-E6 strain that VZV-Oka live attenuated varicella vaccine strain grew in Vero E6 cells, Vero E6 cells were infected with VZV-Oka-E6 of three different doses (104.65, 104.95 and 105.25 TCID50), and the cytopathic effect was observed under a microscope to determine the optimal infection dose of VZV-Oka-E6 strain. Then the detectable sensitivity of the infected cell antigen slides prepared after fixing the infected cells with different fixatives was compared to determine the optimal fixative. As a result, the FAMA method based on Vero E6 cells for the determination of neutralizing anti-VZV has been developed. The established FAMA assay was used to detect the international standard for varicella zoster immunoglobulin with different titers to determine the sensitivity of the assay. The specificity of the assay was evaluated by detecting specific antibodies against human herpes simplex virus (HSV) type 1 and type 2. The neutralizing anti-VZV antibodies of the international standard for varicella zoster immunoglobulin were detected using VZV-infected cell antigen slides prepared in the same batch and four different batches, respectively, to determine the intra-assay repeatability and inter-assay repeatability. The international standard for varicella zoster immunoglobulin with three known titers was detected to evaluate the relative accuracy of this assay. The anti-VZV titers in 20 apheresis plasma samples were determined with the newly established FAMA test and ELISA test, respectively, and the detection results of the two methods were compared using Spearman’s correlation test. 【Results】 The optimal infection dose of the VZV-Oka-E6 strain in FAMA assay was determined to be 105.25 TCID50, and acetone precooled at -20℃ was used as the fixative. The FAMA test has a high sensitivity with a detecting limit of 31.25 mIU/mL for neutralizing anti-VZV titers. The negative result was observed when detecting herpes simplex virus (HSV) type 1 and 2 specific antibodies. The international standard for varicella zoster immunoglobulin was detected by VZV infected cell antigen slides prepared in the same batch and 4 different batches, with the coefficient of variation being 29.95% and 26.71%, respectively. The detection value of the international standard for varicella zoster immunoglobulin with three different titer levels was consistent with their theoretical value. The correlation coefficient of the detection results of 20 apheresis plasma samples by the FAMA test and ELISA test was 0.268. 【Conclusion】 The VZV FAMA assay has good sensitivity, specificity, repeatability, and relative accuracy in detecting neutralizing anti-VZV titers. It can be applied for detecting neutralizing anti-VZV titers in apheresis plasma samples as well as the varicella-zoster immunoglobulin (VZIG) preparations.

Morphology and morphogenesis of SARS-CoV-2 in Vero-E6 cells

BACKGROUND The coronaviruses (CoVs) called the attention of the world for causing outbreaks of severe acute respiratory syndrome (SARS-CoV), in Asia in 2002-03, and respiratory disease in the Middle East (MERS-CoV), in 2012. In December 2019, yet again a new coronavirus (SARS-CoV-2) first identified in Wuhan, China, was associated with a severe respiratory infection, known today as COVID-19. This new virus quickly spread throughout China and 30 additional countries. As result, the World Health Organization (WHO) elevated the status of the COVID-19 outbreak from emergency of international concern to pandemic on March 11, 2020. The impact of COVID-19 on public health and economy fueled a worldwide race to approve therapeutic and prophylactic agents, but so far, there are no specific antiviral drugs or vaccines available. In current scenario, the development of in vitro systems for viral mass production and for testing antiviral and vaccine candidates proves to be an urgent matter. OBJECTIVE The objective of this paper is study the biology of SARS-CoV-2 in Vero-E6 cells at the ultrastructural level. METHODS In this study, we documented, by transmission electron microscopy and real-time reverse transcription polymerase chain reaction (RT-PCR), the infection of Vero-E6 cells with SARS-CoV-2 samples isolated from Brazilian patients. FINDINGS The infected cells presented cytopathic effects and SARS-CoV-2 particles were observed attached to the cell surface and inside cytoplasmic vesicles. The entry of the virus into cells occurred through the endocytic pathway or by fusion of the viral envelope with the cell membrane. Assembled nucleocapsids were verified inside rough endoplasmic reticulum cisterns (RER). Viral maturation seemed to occur by budding of viral particles from the RER into smooth membrane vesicles. MAIN CONCLUSIONS Therefore, the susceptibility of Vero-E6 cells to SARS-CoV-2 infection and the viral pathway inside the cells were demonstrated by ultrastructural analysis.

Freeze-dried rabies vaccine followed by death due to septic shock： a case report / 上海预防医学

ObjectiveTo analyze a case of death after inoculation of a freeze-dried rabies vaccine for human use so as to provide reference for the vaccination of the rabies vaccine and the process of investigation and diagnosis involving adverse events following immunization （AEFI） in the future. MethodsData on vaccination， clinical symptoms， treatments， investigation and diagnosis were collected and analyzed. ResultsRabies post-exposure prophylaxis and vaccination were in line with the protocols. On the 3rd day after the inoculation of the rabies vaccine， the patient developed fever， weakness， headache， dizziness， diarrhea and other symptoms. The white blood cell count and neutrophil count increased progressively. At about 17：00 on the same day， the patient suffered a sudden cardiac arrest and died clinically. Autopsy was not carried out. ConclusionThe cause of sepsis /septic shock of the patient is unknown. It is necessary to formulate detailed rabies immunization procedures as well as norms and expert consensus in the field of investigation and diagnosis of AEFI.

Freeze-dried rabies vaccine followed by death due to septic shock： a case report / 上海预防医学

ObjectiveTo analyze a case of death after inoculation of a freeze-dried rabies vaccine for human use so as to provide reference for the vaccination of the rabies vaccine and the process of investigation and diagnosis involving adverse events following immunization （AEFI） in the future. MethodsData on vaccination， clinical symptoms， treatments， investigation and diagnosis were collected and analyzed. ResultsRabies post-exposure prophylaxis and vaccination were in line with the protocols. On the 3rd day after the inoculation of the rabies vaccine， the patient developed fever， weakness， headache， dizziness， diarrhea and other symptoms. The white blood cell count and neutrophil count increased progressively. At about 17：00 on the same day， the patient suffered a sudden cardiac arrest and died clinically. Autopsy was not carried out. ConclusionThe cause of sepsis /septic shock of the patient is unknown. It is necessary to formulate detailed rabies immunization procedures as well as norms and expert consensus in the field of investigation and diagnosis of AEFI.

Suspension culture of Vero cells for the production of adenovirus type 5

Human platelet lysate efficiency, stability, and optimal heparin concentration required in culture of mammalian cells

BACKGROUND: Fetal bovine serum (FBS) has been used to support the growth and proliferation of mammalian cells for decades. Owing to several risk factors associated with FBS, several trials have been conducted to evaluate substitutes to FBS with the same efficiency and the lower risk issues.METHODS: In this study, human platelet lysate (HPL) derived from activated human platelets was evaluated as an alternative to FBS due to the associated risk factors. To evaluate the efficiency of the preparation process, platelet count was performed before and after activation. The concentrations of several growth factors and proteins were measured to investigate HPL efficiency. HPL stability was studied at regular intervals, and optimal heparin concentration required to prevent gel formation in various media was determined. The biological activity of HPL and FBS was compared by evaluating the growth performance of Vero and Hep-2 cell lines.RESULTS: Result of platelet count assay revealed the efficiency of HPL preparation process. Growth factor concentrations in HPL were significantly higher than those in FBS, while the protein content of HPL was lower than that of FBS. Stability study data showed that the prepared HPL was stable for up to 15 months at −20℃. Ideal heparin concentration to be used in different media was dependent on calcium concentration. Results of cell viability assay showed that HPL was superior to FBS in supporting the growth and proliferation of Vero and Hep-2 cells.CONCLUSION: The HPL prepared by the mechanical activation of platelets may serve as an efficient alternative to FBS in cell culture process.

High-density culture of Vero cells in novel perfusion bioreactor system

Viruses are the obligatory intracellular parasites infecting microbes, plants, animals, and humans. They aredead outside host cell but can take-over the host’s cell machinery as soon as they are into it. Several studies oninhibitor compounds have been done for animal viruses including those that are affecting humans, but thereis inadequacy in terms of research and literature for plant viruses that are responsible for losses in crop yieldand quality loss all across the globe. This could be focal point to study plant viruses, their transmission andpathogenicity, and to establish widely used, effective, and advanced approaches for their control. The purposeof this review is to discuss various approaches to control plant viruses that have been developed and applied tocombat plant viral infections. We have divided these approaches into two categories conventional (meristemtip culture, cryotherapy, thermotherapy, and chemotherapy) and advanced (nucleic acid-based approacheslike RNA Silencing, cross-protection, transgenic plants, gene pyramiding, and protein-protein interaction).Moreover, we have discussed and compared the principles, methodologies, advantages, and disadvantages ofeach technique. The approaches have been explored to promote their application in best suited way on variousplants to control viral diseases and to improve food crops quality with increase in production.

Comparative assessment of the replication efficiency of dengue, yellow fever, and chikungunya arboviruses in some insect and mammalian cell lines

Abstract INTRODUCTION: Insect cell cultures play an essential role in understanding arboviral replication. However, the replicative efficiency of some of these viruses such as dengue (DENV), yellow fever (YFV), and chikungunya (CHIKV) in a new cellular substrate (Lulo) and in the other two recognized cell lines has not been comparatively assessed. METHODS: Vero, C6/36, and Lulo cell lines were infected with DENV, YFV, and CHIKV. The viral progeny was quantified through plaque assays and quantitative reverse transcription-polymerase chain reaction, while for DENV2, the findings were confirmed by immunofluorescence antibody assay. RESULTS: The higher DENV2 titer (from multiplicity of infection 0.001) was obtained on day four post-infection in C6/36 and on day six in Vero cells, while the Lulo cell line was almost impossible to infect under the same conditions. However, C6/36 showed the highest values of viral RNA production compared to Vero cells, while the quantification of the viral RNA in Lulo cells showed high levels of viral genomes, which had no correlation to the infectious viral particles. CONCLUSIONS: C6/36 was the most efficient cell line in the alpha and flavivirus production, followed by Vero cells. Thus, Lulo cells may be a useful substrate to study the mechanisms by which cells evade viral replication.

Construction of influenza B virus vero cell adapted strain by genetic reassortment / 中华实验和临床病毒学杂志

Objective@#To construct influenza B virus Vero cell adapted strain by genetic recombination technology by using the influenza B virus Vero cell adapted strain as the parent strain.@*Methods@#The chick embryo and Vero cell were co-infected with influenza virus Vero cell adapted strain B/Malaysia/2506/2004 Va (Bv) and the vaccine strain B/massachusetts/2/2012 (BX-51B) recommended by WHO. The reassortants were screened with the anti-Bv serum. Plaque-purified reassortants were used to screen for Vero cell-adapted influenza B virus strains containing the surface antigen of the epidemic strain.@*Results@#A Vero cell-adapted influenza B virus strain was obtained with successive passage in Vero cells. The hemagglutination inhibition test and the one-way immunogold agar diffusion test both showed that the reassortant virus was homologous to NYMC BX-51B, and sequence analysis result showed that the reassortment virus has the same HA and NA gene with the vaccine strain.@*Conclusion@#B/Malaysia/2506/2004Va (Bv) can be used as a parent strain to prepare Vero cell vaccine against influenza B virus.

Virulência e multiplicação de isolados de Toxoplasma gondii da região central do Rio Grande do Sul / Virulence and multiplication of Toxoplasma gondii isolates from the central region of Rio Grande do Sul, Brazil

O protozoário Toxoplasma gondii possui a capacidade de infectar diversas espécies animais, geralmente causando distúrbios reprodutivos. Quatro diferentes isolados de T. gondii - Pains #1 (P1), Pains #2 (P2), Santa Flora #1 (SF1) e Santa Flora #306 (SF306) - foram avaliados, após prévia genotipagem. A capacidade de multiplicação e virulência destes isolados foi analisada in vitro (células Vero) e in vivo (camundongos), sendo realizadas 3 passagens para cada isolado em cada modo avaliado, sendo sempre inoculada a dose de 1x104 taquizoítos em todas as passagens. Os camundongos eram observados diariamente, quanto à presença de sinais clínicos e ocorrência de mortalidade após inoculação dos taquizoítos. Os isolados SF1 e SF306, foram os que apresentaram maior multiplicação média do número total de taquizoítos em cada uma das 3 diferentes passagens realizadas para cada um dos isolados tanto in vitro quanto in vivo. Os primeiros sinais clínicos observados nos camundongos ocorreram entre os dias 5 a 11, após inoculação, com mortalidade acontecendo entre os dias 6 a 15, após inoculação. Assim, a multiplicação parasitária in vitro é semelhante à multiplicação in vivo destes isolados de T. gondii; diferentes isolados com o mesmo genótipo apresentam comportamento de virulência semelhante, caracterizando o isolado SF1 como mais virulento para camundongos.(AU)

The protozoan Toxoplasma gondii has the ability to infect several animal species, usually causing reproductive disorders. Four different isolates of T. gondii - Pains #1 (P1), Pains #2 (P2), Santa Flora #1 (SF1) and Santa Flora #306 (SF306) were evaluated with prior genotyping. Their virulence and multiplication capacity were analyzed in vitro (Vero cells) and in vivo (mice). For each isolate, three passages were performed with dose inoculation 1x104 tachyzoites at each passage. The mice were daily observed to verify of clinical signs and occurrence of mortality after tachyzoites inoculation. The SF1 isolate and SF306 isolate, presented the highest multiplication of the total tachyzoites number in each of the 3 different passages performed in vitro and in vivo. The initial clinical signs in mice were observed between 5 and 11 days, and occurring mortality between 6 and 15 days, after inoculation. Thus, the parasitic multiplication of theses isolates is similar in vitro and in vivo; different isolates within the same genotype have a similar virulence and the SF1 isolate is the most virulent for mice.(AU)

Antifungal and cytotoxic activities of extracts obtained from underutilised edible tropical fruits

Objective: To evaluate antifungal and cytotoxic activities of four underutilised fruit species, i.e. Artocarpus altilis (breadfruit), Cynometra cauliflora (nam-nam), Mangifera pajang (M. pajang) (Bambangan) and Physalis minima (wild gooseberry). Methods: Extracts from the fresh flesh of Artocarpus altilis and Cynometra cauliflora, the flesh and kernel of M. pajang, and the whole fruit of Physalis minima were obtained by sequential extraction using hexane, chloroform, ethyl acetate, ethanol, methanol and distilled water. Each extract was assessed against six species of human fungal pathogens using a colourimetric broth microdilution method. The cytotoxicity was evaluated using African monkey kidney epithelial (Vero) cells. Results: All 30 extracts showed inhibitory activity against Cryptococcus neoformans. However, none of the extracts were active against Aspergillus fumigatus. The ethanol, methanol and water extracts from the kernel of M. pajang fruit showed the strongest activity against three species of Candida and Trichophyton interdigitale, with a minimum inhibitory concentration range of 0.001 - 0.630 mg/mL. The corresponding mean 50% cytotoxic concentrations for these three extracts were 358.7, 158.4 and 261.3 μg/mL, respectively against Vero cells. In contrast, the flesh of M. pajang fruit (hexane, chloroform and ethyl acetate extracts) showed statistically significant (P<0.001; ANOVA) strong toxicity against the cells, with 30.6, 13.5 and 22.2 μg/mL of mean values of 50% cytotoxic concentrations, respectively. Conclusions: The results suggest that the bioactivity of the kernel of M. pajang fruit is more selective towards fungi and thus is a potential source of new antifungal agents.

Antifungal and cytotoxic activities of extracts obtained from underutilised edible tropical fruits

Objective: To evaluate antifungal and cytotoxic activities of four underutilised fruit species,i.e. Artocarpus altilis (breadfruit), Cynometra cauliflora (nam-nam), Mangifera pajang (M.pajang) (Bambangan) and Physalis minima (wild gooseberry). Methods: Extracts from the fresh flesh of Artocarpus altilis and Cynometra cauliflora, the flesh and kernel of M. pajang,and the whole fruit of Physalis minima were obtained by sequential extraction using hexane, chloroform, ethyl acetate, ethanol, methanol and distilled water. Each extract was assessed against six species of human fungal pathogens using a colourimetric broth microdilution method. The cytotoxicity was evaluated using African monkey kidney epithelial (Vero) cells.Results: All 30 extracts showed inhibitory activity against Cryptococcus neoformans. However,none of the extracts were active against Aspergillus fumigatus. The ethanol, methanol and water extracts from the kernel of M. pajang fruit showed the strongest activity against three species of Candida and Trichophyton interdigitale, with a minimum inhibitory concentration range of 0.001 – 0.630 mg/mL. The corresponding mean 50％ cytotoxic concentrations for these three extracts were 358.7, 158.4 and 261.3 μg/mL, respectively against Vero cells. In contrast, the flesh of M. pajang fruit (hexane, chloroform and ethyl acetate extracts) showed statistically significant (P<0.001; ANOVA) strong toxicity against the cells, with 30.6, 13.5 and 22.2 μg/mL of mean values of 50％ cytotoxic concentrations, respectively. Conclusions: The results suggest that the bioactivity of the kernel of M. pajang fruit is more selective towards fungi and thus is a potential source of new antifungal agents.