Antigenic protein modifications in Ehrlichia

To develop effective vaccination strategies againstEhrlichia, we have previously reported developing an animal model of cross-protection in which C57BL/6 mice primed withE. muris were resistant to lethal infection withIxodes ovatus ehrlichia (IOE). Polyclonal antibody produced in mice after priming withE. muris and later injected with IOE-detected antigenic proteins inE. muris and IOE cell lysates. Cross-reaction of antigenic proteins was observed when we probed both theE. muris and IOE cell lysates with IOE andE. muris-specific polyclonal antibody. Analysis of the total proteins ofE. muris and IOE by two dimensional electrophoresis showed that bothE. muris and IOE have the same antigenic proteins. Finally, studies on post-translational protein modifications using a novel technique, Eastern blotting, showed thatE. muris proteins are more lipoylated and glycosylated than those of IOE

The NSP3 protein of SARS-CoV-2 binds fragile X mental retardation proteins to disrupt UBAP2L interactions

Viruses interact with numerous host factors to facilitate viral replication and to dampen antiviral defense mechanisms. We currently have a limited mechanistic understanding of how SARS-CoV-2 binds host factors and the functional role of these interactions. Here, we uncover a novel interaction between the viral NSP3 protein and the fragile X mental retardation proteins (FMRPs: FMR1, FXR1-2). SARS-CoV-2 NSP3 mutant viruses preventing FMRP binding have attenuated replication in vitro and reduced levels of viral antigen in lungs during the early stages of infection. We show that a unique peptide motif in NSP3 binds directly to the two central KH domains of FMRPs and that this interaction is disrupted by the I304N mutation found in a patient with fragile X syndrome. NSP3 binding to FMRPs disrupts their interaction with the stress granule component UBAP2L through direct competition with a peptide motif in UBAP2L to prevent FMRP incorporation into stress granules. Collectively, our results provide novel insight into how SARS-CoV-2 hijacks host cell proteins and provides molecular insight into the possible underlying molecular defects in fragile X syndrome

Structure-Based Vaccines Provide Protection in a Mouse Model of Ehrlichiosis

infection. were protected against the pathogen.Our results demonstrate the power of structural vaccines and could be a new strategy in the development of vaccines to provide protection against pathogenic microorganisms

Phylogenetic analysis of the rompB genes of Rickettsia felis and Rickettsia prowazekii European-human and North American flying-squirrel strains

The rickettsial outer membrane protein B (rompB) gene encodes the major surface antigens of Rickettsia species. We undertook sequencing and molecular analysis of the rompB gene of Rickettsia felis and a comparison with its homologs in spotted fever group (SFG) and typhus group (TG) rickettsiae, including the complete sequences of two North American flying squirrel strains and two European human strains of Rickettsia prowazekii. We sequenced 5,226 base pairs (bp) of the R. felis rompB, encoding a protein of 1,654 amino acids. We also sequenced 5,015 bp of rompB of the flying squirrel strains, encoding a protein of 1,643 amino acids. Analysis of the R. felis rompB gene sequence showed 10-13% divergence from SFG rickettsiae and 18% divergence from the TG rickettsiae. The rompB of all sequenced strains of R. prowazekii showed an overall similarity of 99.7-99.9%

Protection induced by <i>Ehrlichia</i> Hsp60 _43–63 and P28-19 _55–75 peptides was associated with induction of <i>Ehrlichia</i>- specific IgG antibody.

<p>(A) <i>Ehrlichia</i> Hsp60 _43–63 vaccinated mice induced higher IgG antibody levels after challenge with <i>E.</i> muris compared to unvaccinated <i>E. muris</i>-infected mice (***<i>p</i><0.001 as determined by t test). (B) P28-19 _55–75 peptide vaccinated mice induced higher IgG antibody levels after <i>E. muris</i> challenge compared to unvaccinated <i>E. muris-</i>infected mice (***<i>p</i><0.001 as determined by Student <i>t</i> test).</p

P28-19 _55-75 peptide reacted with <i>E. muris</i> antibody.

<p>The peptide corresponding to the predicted hydrophilic sequence of amino acids 55–75 of P28-19 reacted with <i>Ehrlichia</i> antibody. The peptide was found to be more sensitive in reacting with the <i>Ehrlichia</i> antibody than the recombinant P28-19 protein (***<i>p</i><0.001 as determined by Student <i>t</i> test).</p

Antibody isotypes in mice immunized with <i>Ehrlichia</i> Hsp60 _43–63 and P28-19 _55–75 peptides.

<p>(A) Mice vaccinated with <i>Ehrlichia</i> Hsp60 _43–63 peptide had higher levels of IgG1, IgG2c, IgG2b, and IgG3 compared to unvaccinated mice after bacterial challenge. (B) Mice vaccinated with P28-19 _55–75 peptide had higher levels of IgG1, IgG2b, IgG2c, and IgG3 compared to unvaccinated mice after bacterial challenge. The data were expressed as mean plus standard deviation and three mice per group were included for analysis.</p