scholarly journals THE ADAPTATION OF UNMODIFIED STRAINS OF YELLOW FEVER VIRUS TO CULTIVATION IN VITRO

1937 ◽  
Vol 65 (6) ◽  
pp. 801-808 ◽  
Author(s):  
Hugh H. Smith ◽  
Max Theiler

1. In a search for suitable tissues for the cultivation of yellow fever virus in vitro, mouse embryos were inoculated with this virus in utero. A titration for virus content of the various organs of the embryos indicated that the virus was present in the brain in greatest concentration. 2. Unmodified strains of yellow fever virus were readily adapted to cultivation in vitro in a medium consisting of minced mouse embryo brain tissue and Tyrode solution containing 10 per cent normal monkey serum. 3. After a continued cultivation in mouse embryo brain tissue cultures for twenty to twenty-five subcultures, these strains were readily adapted to cultivation in whole mouse embryo tissue medium. 4. There is evidence to indicate that a prolonged cultivation of the virus in mouse embryo brain medium increases its neurotropic properties. 5. Attempts to employ monkey tissues for in vitro cultivation of yellow fever virus gave entirely negative results.

1937 ◽  
Vol 65 (6) ◽  
pp. 787-800 ◽  
Author(s):  
Max Theiler ◽  
Hugh H. Smith

The response of rhesus monkeys to a subcutaneous inoculation with varying amounts of virus modified by prolonged cultivation in vitro has been studied. The tissue components of the medium consisted of chick embryo tissue containing minimal amounts of nervous tissue. The immunity produced in monkeys, as measured by the antibody titer developed, has no relation to the amount of virus inoculated. Monkeys inoculated subcutaneously with the tissue culture virus are rendered immune to a subsequent injection of a highly virulent yellow fever virus. This resistance is already present 7 days after vaccination. The subcutaneous inoculation of the culture virus into immune persons leads to a substantial increase of the serum antibody titer. The results of vaccinating eight normal persons with culture virus are presented. The reactions were minimal. The highest temperature recorded following vaccination was 37.4°C. The sera taken from the eight vaccinated persons 2 to 4 weeks after inoculation with the tissue culture virus showed the presence of yellow fever antibodies.


1937 ◽  
Vol 65 (6) ◽  
pp. 767-786 ◽  
Author(s):  
Max Theiler ◽  
Hugh H. Smith

1. Experimental evidence is presented to show that prolonged cultivation of yellow fever virus in vitro results in a change in its pathogenicity, and that this change varies with the type of tissues used for the cultivation. 2. In the tissue cultures used for the propagation of the virus, three different types of tissues were used. They included whole mouse embryo, chick embryo from which the head and spinal cord had been removed, and testicular tissues of mice and guinea pigs. 3. The changes in the pathogenicity of the virus cultivated for a period of over 3 years in a medium containing the tissues of whole mouse embryo were not striking. The viscerotropic virulence of the virus appeared somewhat diminished, in that when injected subcutaneously into rhesus monkeys or hedgehogs it failed to produce a fatal infection, although there is evidence to indicate that a generalized infection takes place as demonstrated by the appearance of virus in the circulating blood in relatively high concentration during infection. The neurotropic virulence of the virus remained unaltered during the cultivation in this medium. 4. The changes in the pathogenicity of the virus cultivated in medium containing tissues of chick embryo from which the head and spinal cord had been removed were very pronounced. The viscerotropic virulence of the virus was lost to a large extent. When injected subcutaneously into monkeys there was as a rule a very mild generalized infection, as demonstrated by the minimal quantities of virus found in the circulating blood. Its neurotropism was also much diminished. When injected into monkeys intracerebrally, it no longer produced a fatal encephalitis but only a moderate febrile reaction, followed by recovery and solid immunity to reinoculation with a highly virulent strain of virus. When injected intracerebrally into mice, the mortality ratio was not diminished but the incubation period was markedly prolonged. 5. The changes in the pathogenicity of the virus cultivated in medium containing testicular tissues were somewhat similar to those observed after cultivation in chick embryo medium which contained only a minimal amount of nervous tissue. Its viscerotropic affinity had been largely lost and only very small amounts of virus were found in the circulating blood of monkeys inoculated subcutaneously. Given intracerebrally, it produced death from encephalitis in monkeys. The incubation period in mice inoculated intracerebrally with this virus was also prolonged but somewhat less so than with the virus grown in chick embryo tissues without the central nervous system.


Viruses ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 802
Author(s):  
Michael B. Yakass ◽  
David Franco ◽  
Osbourne Quaye

Flaviviruses are constantly evolving diverse immune evasion strategies, and the exploitation of the functions of suppressors of cytokine signalling (SOCS) and protein inhibitors of activated STATs (PIAS) to favour virus replication has been described for Dengue and Japanese encephalitis viruses but not for yellow fever virus (YFV), which is still of global importance despite the existence of an effective vaccine. Some mechanisms that YFV employs to evade host immune defence has been reported, but the expression patterns of SOCS and PIAS in infected cells is yet to be determined. Here, we show that SOCS1 is down-regulated early in YFV-infected HeLa and HEK 293T cells, while SOCS3 and SOCS5 are not significantly altered, and PIAS mRNA expression appears to follow a rise-dip pattern akin to circadian-controlled genes. We also demonstrate that YFV evades interferon-β application to produce comparable viral titres. This report provides initial insight into the in vitro expression dynamics of SOCS and PIAS upon YFV infection and a basis for further investigation into SOCS/PIAS expression and how these modulate the immune response in animal models.


2019 ◽  
Vol 13 (1) ◽  
pp. e0007072 ◽  
Author(s):  
Caroline S. de Freitas ◽  
Luiza M. Higa ◽  
Carolina Q. Sacramento ◽  
André C. Ferreira ◽  
Patrícia A. Reis ◽  
...  

2009 ◽  
Vol 8 (1) ◽  
pp. 8 ◽  
Author(s):  
Rocio Meneses Lopez ◽  
Raquel E Ocazionez ◽  
Jairo R Martinez ◽  
Elena E Stashenko

The Lancet ◽  
1940 ◽  
Vol 236 (6102) ◽  
pp. 163-164 ◽  
Author(s):  
G.M. Findlay ◽  
F.O. Maccallum

2004 ◽  
Vol 78 (2) ◽  
pp. 1032-1038 ◽  
Author(s):  
Konstantin V. Pugachev ◽  
Farshad Guirakhoo ◽  
Simeon W. Ocran ◽  
Fred Mitchell ◽  
Megan Parsons ◽  
...  

ABSTRACT Three consecutive plaque purifications of four chimeric yellow fever virus-dengue virus (ChimeriVax-DEN) vaccine candidates against dengue virus types 1 to 4 were performed. The genome of each candidate was sequenced by the consensus approach after plaque purification and additional passages in cell culture. Our data suggest that the nucleotide sequence error rate for SP6 RNA polymerase used in the in vitro transcription step to initiate virus replication was as high as 1.34 × 10−4 per copied nucleotide and that the error rate of the yellow fever virus RNA polymerase employed by the chimeras for genome replication in infected cells was as low as 1.9 × 10−7 to 2.3 × 10−7. Clustering of beneficial mutations that accumulated after multiple virus passages suggests that the N-terminal part of the prM protein, a specific site in the middle of the E protein, and the NS4B protein may be essential for nucleocapsid-envelope interaction during flavivirus assembly.


2021 ◽  
Author(s):  
Kai Lin ◽  
Steven S Good ◽  
Justin G. Julander ◽  
Abbie Weight ◽  
Adel Moussa

Yellow fever virus (YFV) is a zoonotic pathogen re-emerging in parts of the world, causing a viral hemorrhagic fever associated with high mortality rates. While an effective vaccine is available, having an effective antiviral against YFV is critical against unexpected outbreaks, or when vaccination is not recommended. We have previously identified AT-281, the free base of AT-752, an orally available double prodrug of a guanosine nucleotide analog, as a potent inhibitor of YFV in vitro , with a 50% effective concentration (EC 50 ) of 0.31 µM. In hamsters infected with YFV (Jimenez strain), viremia rose about 4 log 10 -fold and serum alanine aminotransferase (ALT) 2-fold compared to sham-infected animals. Treatment with 1000 mg/kg AT-752 for 7 days, initiated 4 h prior to viral challenge, reduced viremia to below the limit of detection by day 4 post infection (pi) and returned ALT to normal levels by day 6 pi. When treatment with AT-752 was initiated 2 days pi, the virus titer and ALT dropped >2 log 10 and 53% by day 4 and 6 pi, respectively. In addition, at 21 days pi, 70 – 100% of the infected animals in the treatment groups survived compared to 0% of the untreated group (p<0.001). Moreover, in vivo formation of the active triphosphate metabolite AT-9010 was measured in the animal tissues, with the highest concentrations in liver and kidney, organs that are vulnerable to the virus. The demonstrated in vivo activity of AT-752 suggests that it is a promising compound for clinical development in the treatment of YFV infection.


2010 ◽  
Vol 84 (21) ◽  
pp. 11395-11406 ◽  
Author(s):  
Patrícia A. G. C. Silva ◽  
Carina F. Pereira ◽  
Tim J. Dalebout ◽  
Willy J. M. Spaan ◽  
Peter J. Bredenbeek

ABSTRACT Cells and mice infected with arthropod-borne flaviviruses produce a small subgenomic RNA that is colinear with the distal part of the viral 3′-untranslated region (UTR). This small subgenomic flavivirus RNA (sfRNA) results from the incomplete degradation of the viral genome by the host 5′-3′ exonuclease XRN1. Production of the sfRNA is important for the pathogenicity of the virus. This study not only presents a detailed description of the yellow fever virus (YFV) sfRNA but, more importantly, describes for the first time the molecular characteristics of the stalling site for XRN1 in the flavivirus genome. Similar to the case for West Nile virus, the YFV sfRNA was produced by XRN1. However, in contrast to the case for other arthropod-borne flaviviruses, not one but two sfRNAs were detected in YFV-infected mammalian cells. The smaller of these two sfRNAs was not observed in infected mosquito cells. The larger sfRNA could also be produced in vitro by incubation with purified XRN1. These two YFV sfRNAs formed a 5′-nested set. The 5′ ends of the YFV sfRNAs were found to be just upstream of the previously predicted RNA pseudoknot PSK3. RNA structure probing and mutagenesis studies provided strong evidence that this pseudoknot structure was formed and served as the molecular signal to stall XRN1. The sequence involved in PSK3 formation was cloned into the Sinrep5 expression vector and shown to direct the production of an sfRNA-like RNA. These results underscore the importance of the RNA pseudoknot in stalling XRN1 and also demonstrate that it is the sole viral requirement for sfRNA production.


Virus Genes ◽  
2009 ◽  
Vol 38 (2) ◽  
pp. 224-231 ◽  
Author(s):  
Carolina C. Pacca ◽  
Adriana A. Severino ◽  
Adriano Mondini ◽  
Paula Rahal ◽  
Solange G. P. D’avila ◽  
...  

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