A hyper-glycosylation of HBV surface major hydrophilic region correlates with immunosuppression-driven HBV reactivation and hampers HBsAg recognition in vitro

2015 ◽  
Vol 47 ◽  
pp. e11-e12
Author(s):  
L. Colagrossi ◽  
R. Salpini ◽  
M. Surdo ◽  
A. Battisti ◽  
M. Pollicita ◽  
...  
Keyword(s):  
Hbv Reactivation ◽  
Major Hydrophilic Region ◽  
Hydrophilic Region

scholarly journals A Hyper-Glycosylation of HBV Surface Antigen Correlates with HBsAg-Negativity at Immunosuppression-Driven HBV Reactivation in Vivo and Hinders HBsAg Recognition In Vitro

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 251 ◽  
Author(s):  
Romina Salpini ◽  
Lorenzo Piermatteo ◽  
Arianna Battisti ◽  
Luna Colagrossi ◽  
Marianna Aragri ◽  
...  
Keyword(s):  
Surface Antigen ◽  
Immune Escape ◽  
Hbv Dna ◽  
Hbv Reactivation ◽  
Single Mutation ◽  
Triple Mutant ◽  
Major Hydrophilic Region ◽  
Hbv Replication ◽  
Antigenic Properties

Immune-suppression driven Hepatitis B Virus (HBV)-reactivation poses serious concerns since it occurs in several clinical settings and can result in severe forms of hepatitis. Previous studies showed that HBV strains, circulating in patients with HBV-reactivation, are characterized by an enrichment of immune-escape mutations in HBV surface antigen (HBsAg). Here, we focused on specific immune-escape mutations associated with the acquisition of N-linked glycosylation sites in HBsAg (NLGSs). In particular, we investigated profiles of NLGSs in 47 patients with immunosuppression-driven HBV-reactivation and we evaluated their impact on HBsAg-antigenicity and HBV-replication in vitro. At HBV-reactivation, despite a median serum HBV-DNA of 6.7 [5.3–8.0] logIU/mL, 23.4% of patients remained HBsAg-negative. HBsAg-negativity at HBV-reactivation correlated with the presence of >1 additional NLGSs (p < 0.001). These NLGSs are located in the major hydrophilic region of HBsAg (known to be the target of antibodies) and resulted from the single mutation T115N, T117N, T123N, N114ins, and from the triple mutant S113N+T131N+M133T. In vitro, NLGSs strongly alter HBsAg antigenic properties and recognition by antibodies used in assays for HBsAg-quantification without affecting HBsAg-secretion and other parameters of HBV-replication. In conclusion, additional NLGSs correlate with HBsAg-negativity despite HBV-reactivation, and hamper HBsAg-antigenicity in vitro, supporting the role of NGSs in immune-escape and the importance of HBV-DNA for a proper diagnosis of HBV-reactivation.

N-glycosylation mutations within hepatitis B virus surface major hydrophilic region contribute mostly to immune escape

2014 ◽  
Vol 60 (3) ◽  
pp. 515-522 ◽  
Author(s):  
De-Min Yu ◽  
Xin-Hua Li ◽  
Vannary Mom ◽  
Zhong-Hua Lu ◽  
Xiang-Wei Liao ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Immune Escape ◽  
Major Hydrophilic Region ◽  
Virus Surface ◽  
B Virus ◽  
Hydrophilic Region

scholarly journals Polo-Like Kinase 1 as a Target for Human Cytomegalovirus pp65 Lower Matrix Protein

1999 ◽  
Vol 73 (2) ◽  
pp. 1468-1478 ◽  
Author(s):  
A. Gallina ◽  
L. Simoncini ◽  
S. Garbelli ◽  
E. Percivalle ◽  
G. Pedrali-Noy ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Matrix Protein ◽  
Kinase Activity ◽  
Major Constituent ◽  
Early Protein ◽  
Vitro Binding ◽  
A Cell ◽  
Bona Fide ◽  
Hydrophilic Region

ABSTRACT Human cytomegalovirus (HCMV) pp65 protein is the major constituent of viral dense bodies but is dispensable for viral growth in vitro. pp65 copurifies with a S/T kinase activity and has been implicated in phosphorylation of HCMV IE1 immediate-early protein and its escape from major histocompatibility complex 1 presentation. Furthermore, the presence of pp65 correlates with a virion-associated kinase activity. To clarify the role of pp65, yeast two-hybrid system (THS) screening was performed to identify pp65 cellular partners. A total of 18 out of 48 yeast clones harboring cDNAs for putative pp65 binding proteins encoded the Polo-like kinase 1 (Plk1) C-terminal domain. Plk1 behaved as a bona fide pp65 partner in THS control crosses, and the interaction was confirmed by in vitro binding experiments. Endogenous Plk1 was coimmunoprecipitated with pp65 from transiently transfected COS7 cells. In infected fibroblasts, Plk1 was coimmunoprecipitated with pp65 at late infection stages. Furthermore, Plk1 was detected within wild-type HCMV particles but not within the particles of a pp65-negative mutant (RVAd65). The hydrophilic region of pp65 was phosphorylated in vitro by Plk1. These results suggest that one function of pp65 may be to capture a cell kinase, perhaps in order to alter its activity, nucleotide preference, substrate specificity, or subcellular localization to the advantage of HCMV.

Prevalence of S gene mutations within the major hydrophilic region of hepatitis B virus in patients in Dongguan, southern China

2017 ◽  
Vol 162 (10) ◽  
pp. 2949-2957 ◽  
Author(s):  
Siping Li ◽  
Mingyu Xie ◽  
Wenrui Li ◽  
Qi Peng ◽  
Baimao Zhong ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Southern China ◽  
Gene Mutations ◽  
Major Hydrophilic Region ◽  
S Gene ◽  
B Virus ◽  
Hydrophilic Region

Identification of a gene cluster for cell-surface genes of the SRS superfamily inNeospora caninumand characterization of the novelSRS9gene

Parasitology ◽  
2011 ◽  
Vol 138 (14) ◽  
pp. 1832-1842 ◽  
Author(s):  
V. RISCO-CASTILLO ◽  
V. MARUGÁN-HERNÁNDEZ ◽  
A. FERNÁNDEZ-GARCÍA ◽  
A. AGUADO-MARTÍNEZ ◽  
E. JIMÉNEZ-RUIZ ◽  
...  
Keyword(s):  
Western Blot ◽  
Gene Cluster ◽  
Neospora Caninum ◽  
Pcr Analysis ◽  
Rt Pcr ◽  
Specific Expression ◽  
Initial Characterization ◽  
Hydrophilic Region

SUMMARYHere we present the detection of a gene cluster forNeospora caninumsurface genes, similar to theToxoplasma gondiiSRS9 locus, and the cloning and characterization of the NcSRS9gene. PCR genome walking, using NcBSR4gene as a framework, allows the identification, upstream NcBSR4, of 2 sequences homologous to theSRS5and the Ubiquinol-cytochrome C reductase genes and, downstream NcBSR4, of an ORF of 1191 bp coding for a 396-amino acid polypeptide with 59% similarity to the TgSRS9 antigen. A putative 39-residue signal peptide was found at the NH2-terminus followed by a hydrophilic region, and a potential site for a glycosylphosphatidylinositol anchor at the COOH-terminus. A recombinant NcSRS9 protein was produced and was recognized on a Western blot by a low proportion of sera from a panel of naturally infected cows and calves. In addition, Western blot analysis using polyclonal anti-rNcSRS9 revealed stage-specific expression of NcSRS9 in bradyzoites but not in tachyzoites, and immunohistochemistry on brain from a congenitally infected calf showed NcSRS9 recognition in bradyzoites contained in tissue cysts. However, bradyzoite-specific expression of NcSRS9 could not be proven by immunofluorescence on bradyzoites obtainedin vitroand RT-PCR analysis showed no significant variations of NcSRS9transcripts duringin vitrotachyzoite-bradyzoite switch, probably due to incomplete maturity ofin vitrobradyzoites. Initial characterization of NcSRS9 in this study may lead to further studies for a better understanding ofN. caninumpersistence.

scholarly journals Transmembrane topology of the mammalian KDEL receptor.

1993 ◽  
Vol 13 (10) ◽  
pp. 6435-6441 ◽  
Author(s):  
P Singh ◽  
B L Tang ◽  
S H Wong ◽  
W Hong
Keyword(s):  
Membrane Protein ◽  
Fusion Proteins ◽  
Integral Membrane Protein ◽  
In Vitro Translation ◽  
Translation System ◽  
Transmembrane Topology ◽  
Amino Terminal ◽  
Hydrophilic Region ◽  
Kdel Receptor

The mammalian KDEL receptor is an integral membrane protein with seven hydrophobic regions. Fusion proteins comprising a 37-kDa N-glycosylation reporter fused downstream of amino-terminal fragments of the KDEL receptor with varying numbers of hydrophobic regions were synthesized in an in vitro translation system containing canine pancreatic microsomes. The luminal or cytosolic orientation of the reporter, and hence of the hydrophilic region to which it is fused, was inferred from the presence or absence of glycosylation, which occurs only in the lumen of the microsomes. The cytosolic orientation of the N and C termini was also confirmed immunocytochemically. Our results suggest that the KDEL receptor is inserted into the membrane with only six transmembrane domains and that both the amino and carboxy termini are located in the cytoplasm.

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