scholarly journals The UL47 gene of avian infectious laryngotracheitis virus is not essential for in vitro replication but is relevant for virulence in chickens

2007 ◽  
Vol 88 (3) ◽  
pp. 732-742 ◽  
Author(s):  
Dorothee Helferich ◽  
Jutta Veits ◽  
Jens P. Teifke ◽  
Thomas C. Mettenleiter ◽  
Walter Fuchs
Keyword(s):  
Deletion Mutant ◽  
Cultured Cells ◽  
Functional Characterization ◽  
Wild Type Virus ◽  
Wild Type ◽  
Infectious Laryngotracheitis Virus ◽  
Live Virus ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus

The genome of infectious laryngotracheitis virus (ILTV) exhibits several differences from those of other avian and mammalian alphaherpesviruses. One of them is the translocation of the conserved UL47 gene from the unique long (UL) to the unique short (US) genome region, where UL47 is inserted upstream of the US4 gene homologue. As in other alphaherpesviruses, UL47 encodes a major tegument protein of ILTV particles, whereas the US4 gene product is a non-structural glycoprotein, gG, which is secreted from infected cells. For functional characterization, an ILTV recombinant was isolated in which US4 together with the 3′-terminal part of UL47 was replaced by a reporter gene cassette encoding green fluorescent protein. From this virus, UL47 and US4 single-gene deletion mutants without foreign sequences were derived and virus revertants were also generated. In vitro studies revealed that both genes were non-essential for ILTV replication in cultured cells. Whereas US4-negative ILTV exhibited no detectable growth defects, maximum virus titres of the double deletion mutant and of UL47-negative ILTV were reduced about 10-fold compared with those of wild-type virus and rescued virus. Experimental infection of chickens demonstrated that UL47-negative ILTV was significantly attenuated in vivo and was shed in reduced amounts, whereas wild-type and rescued viruses caused severe disease and high mortality rates. As all immunized animals were protected against subsequent challenge infection with virulent ILTV, the UL47 deletion mutant might be suitable as a live-virus vaccine.

scholarly journals In Vitro and In Vivo Relevance of Infectious Laryngotracheitis Virus gJ Proteins That Are Expressed from Spliced and Nonspliced mRNAs

2005 ◽  
Vol 79 (2) ◽  
pp. 705-716 ◽  
Author(s):  
Walter Fuchs ◽  
Dorothee Wiesner ◽  
Jutta Veits ◽  
Jens P. Teifke ◽  
Thomas C. Mettenleiter
Keyword(s):  
Severe Disease ◽  
Progeny Virus ◽  
Wild Type ◽  
Infectious Laryngotracheitis Virus ◽  
Live Virus ◽  
Specific Antibodies ◽  
Field Virus ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus

ABSTRACT The positional homologue in the infectious laryngotracheitis virus (ILTV) genome of the glycoprotein gJ gene of herpes simplex virus and the gp2 gene of equine herpesvirus 1 is expressed into four proteins of 85, 115, 160, and 200 kDa (J. Veits, B. Köllner, J. P. Teifke, H. Granzow, T. C. Mettenleiter, and W. Fuchs, Avian Dis. 47:330-342, 2003). RNA analyses revealed that these proteins are expressed from two different late (γ2) transcripts, an unspliced 5.5-kb and a spliced 4.3-kb mRNA that are translated into proteins of 985 and 611 amino acids, respectively. ILTV gJ is incorporated into virions and is modified by N- and O-linked glycosylation. After cotransfection of chicken cells with genomic DNA of a pathogenic ILTV strain and transfer plasmids, gJ-negative ILTV mutants could be isolated. In vitro growth studies demonstrated that deletion of the gJ gene has only minor effects on direct cell-to-cell spread as measured by plaque size. However, progeny virus titers of ILTV-ΔgJ were significantly reduced in comparison to those of the parental virus and a gJ rescue mutant. After experimental infection of chickens the gJ rescue mutant, like wild-type ILTV, caused severe disease and considerable mortality, whereas ILTV-ΔgJ was significantly attenuated. All immunized animals were protected against subsequent challenge infection with virulent ILTV. In sera collected after immunization with the gJ-rescue mutant or with wild-type ILTV, gJ-specific antibodies were detectable by immunofluorescence on cells that had been transfected with a gJ expression plasmid. As expected, no gJ-specific antibodies were found in sera obtained from chickens immunized with ILTV-ΔgJ. Thus, gJ deletion mutants of ILTV might be usable as attenuated live-virus vaccines. Furthermore, the gJ gene might constitute a reliable marker for serological discrimination between vaccinated and field virus-infected chickens.

scholarly journals Infectious Laryngotracheitis Virus Viral Chemokine-Binding Protein Glycoprotein G Alters Transcription of Key Inflammatory Mediators In Vitro and In Vivo

2017 ◽  
Vol 92 (1) ◽  
Author(s):  
Mauricio J. C. Coppo ◽  
Joanne M. Devlin ◽  
Alistair R. Legione ◽  
Paola K. Vaz ◽  
Sang-Won Lee ◽  
...  
Keyword(s):  
Immune Responses ◽  
Binding Protein ◽  
Upper Respiratory Tract ◽  
Infectious Laryngotracheitis Virus ◽  
Glycoprotein G ◽  
Infectious Laryngotracheitis ◽  
Upper Respiratory ◽  
Laryngotracheitis Virus

ABSTRACTInfectious laryngotracheitis virus (ILTV) is an alphaherpesvirus that infects chickens, causing upper respiratory tract disease and significant losses to poultry industries worldwide. Glycoprotein G (gG) is a broad-range viral chemokine-binding protein conserved among most alphaherpesviruses, including ILTV. A number of studies comparing the immunological parameters between infection with gG-expressing and gG-deficient ILTV strains have demonstrated that expression of gG is associated with increased virulence, modification of the amount and the composition of the inflammatory response, and modulation of the immune responses toward antibody production and away from cell-mediated immune responses. The aims of the current study were to examine the establishment of infection and inflammation by ILTV and determine how gG influences that response to infection.In vitroinfection studies using tracheal organ tissue specimen cultures and blood-derived monocytes andin vivoinfection studies in specific-pathogen-free chickens showed that leukocyte recruitment to the site of infection is an important component of the induced pathology and that this is influenced by the expression of ILTV gG and changes in the transcription of the chicken orthologues of mammalian CXC chemokine ligand 8 (CXCL8), chicken CXCLi1 and chicken CXCLi2, among other cytokines and chemokines. The results from this study demonstrate that ILTV gG interferes with chemokine and cytokine transcription at different steps of the inflammatory cascade, thus altering inflammation, virulence, and the balance of the immune response to infection.IMPORTANCEInfectious laryngotracheitis virus is an alphaherpesvirus that expresses gG, a conserved broad-range viral chemokine-binding protein known to interfere with host immune responses. However, little is known about how gG modifies virulence and influences the inflammatory signaling cascade associated with infection. Here, data fromin vitroandin vivoinfection studies are presented. These data show that gG has a direct impact on the transcription of cytokines and chemokine ligandsin vitro(such as chicken CXCL8 orthologues, among others), which explains the altered balance of the inflammatory response that is associated with gG during ILTV infection of the upper respiratory tract of chickens. This is the first report to associate gG with the dysregulation of cytokine transcription at different stages of the inflammatory cascade triggered by ILTV infection of the natural host.

In vitro Infection Studies with Infectious Laryngotracheitis Virus

1986 ◽  
Vol 30 (2) ◽  
pp. 327 ◽  
Author(s):  
B. W. Calnek ◽  
K. J. Fahey ◽  
T. J. Bagust
Keyword(s):  
Infectious Laryngotracheitis Virus ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus

scholarly journals In vitro and in vivo characterization of glycoprotein C-deleted infectious laryngotracheitis virus

2009 ◽  
Vol 91 (4) ◽  
pp. 847-857 ◽  
Author(s):  
S. P. Pavlova ◽  
J. Veits ◽  
U. Blohm ◽  
C. Maresch ◽  
T. C. Mettenleiter ◽  
...  
Keyword(s):  
Infectious Laryngotracheitis Virus ◽  
Glycoprotein C ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus ◽  
In Vivo Characterization

scholarly journals Tradeoffs for a viral mutant with enhanced replication speed

2021 ◽  
Vol 118 (30) ◽  
pp. e2105288118
Author(s):  
Matthew R. Lanahan ◽  
Robert W. Maples ◽  
Julie K. Pfeiffer
Keyword(s):  
Cultured Cells ◽  
Wild Type Virus ◽  
Single Mutation ◽  
Wild Type ◽  
Viral Mutant ◽  
Viral Progeny ◽  
Capsid Protein Vp1 ◽  
Capsid Stability

RNA viruses exist as genetically heterogeneous populations due to high mutation rates, and many of these mutations reduce fitness and/or replication speed. However, it is unknown whether mutations can increase replication speed of a virus already well adapted to replication in cultured cells. By sequentially passaging coxsackievirus B3 in cultured cells and collecting the very earliest progeny, we selected for increased replication speed. We found that a single mutation in a viral capsid protein, VP1-F106L, was sufficient for the fast-replication phenotype. Characterization of this mutant revealed quicker genome release during entry compared to wild-type virus, highlighting a previously unappreciated infection barrier. However, this mutation also reduced capsid stability in vitro and reduced replication and pathogenesis in mice. These results reveal a tradeoff between overall replication speed and fitness. Importantly, this approach—selecting for the earliest viral progeny—could be applied to a variety of viral systems and has the potential to reveal unanticipated inefficiencies in viral replication cycles.

scholarly journals Genotyping of Infectious Laryngotracheitis Virus (ILTV) Isolates from Western Canadian Provinces of Alberta and British Columbia Based on Partial Open Reading Frame (ORF) a and b

Animals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1634
Author(s):  
Catalina Barboza-Solis ◽  
Ana Perez Contreras ◽  
Victor A. Palomino-Tapia ◽  
Tomy Joseph ◽  
Robin King ◽  
...  
Keyword(s):  
British Columbia ◽  
Open Reading Frame ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Infectious Laryngotracheitis Virus ◽  
Group V ◽  
Reading Frame ◽  
Transmission Potential ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus

Infectious laryngotracheitis virus (ILTV) causes an acute upper respiratory disease in chickens called infectious laryngotracheitis (ILT). Live attenuated vaccines are effective in disease control; however, they have residual virulence, which makes them able to replicate, cause disease and revert to the original virulent form. Information is scarce on the molecular nature of ILTV that is linked to ILT in Canada. This study aims to determine whether isolates originating from ILT cases in Western Canada are a wild type or vaccine origin. Samples submitted for the diagnosis of ILT between 2009–2018 were obtained from Alberta (AB, n = 46) and British Columbia (BC, n = 9). For genotyping, a Sanger sequencing of open reading frame (ORF) a and b was used. A total of 27 from AB, and 5 from BC samples yielded a fragment of 1751 base pairs (bp). Three of the BC samples classified as group IV (CEO vaccine strains) and 2 as group V (CEO revertant). Of the AB samples, 22 samples clustered with group V, 3 with group VI (wild type), and 2 with group VII, VIII, and IX (wild type). Overall, 17 non-synonymous single nucleotide polymorphisms (SNPs) were detected. Further studies are underway to ascertain the virulence and transmission potential of these isolates.

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