Persistent, triple-virus co-infections in mosquito cells

<p>Abstract</p> <p>Background</p> <p>It is known that insects and crustaceans can carry simultaneous, active infections of two or more viruses without showing signs of disease, but it was not clear whether co-infecting viruses occupied the same cells or different cells in common target tissues. Our previous work showed that successive challenge of mosquito cell cultures followed by serial, split-passage resulted in stabilized cultures with 100% of the cells co-infected with Dengue virus (DEN) and an insect parvovirus (densovirus) (DNV). By addition of Japanese encephalitis virus (JE), we tested our hypothesis that stable, persistent, triple-virus co-infections could be obtained by the same process.</p> <p>Results</p> <p>Using immunocytochemistry by confocal microscopy, we found that JE super-challenge of cells dually infected with DEN and DNV resulted in stable cultures without signs of cytopathology, and with 99% of the cells producing antigens of the 3 viruses. Location of antigens for all 3 viruses in the triple co-infections was dominant in the cell nuclei. Except for DNV, this differed from the distribution in cells persistently infected with the individual viruses or co-infected with DNV and DEN. The dependence of viral antigen distribution on single infection or co-infection status suggested that host cells underwent an adaptive process to accommodate 2 or more viruses.</p> <p>Conclusions</p> <p>Individual mosquito cells can accommodate at least 3 viruses simultaneously in an adaptive manner. The phenomenon provides an opportunity for genetic exchange between diverse viruses and it may have important medical and veterinary implications for arboviruses.</p

Description of novel capsule biosynthesis loci of Campylobacter jejuni clinical isolates from South and South-East Asia.

Campylobacter jejuni is a major cause of bacterial diarrhea worldwide and associated with numerous sequela, including Guillain-Barré Syndrome, inflammatory bowel disease, reactive arthritis, and irritable bowel syndrome. C. jejuni is unusual for an intestinal pathogen in its ability to coat its surface with a polysaccharide capsule (CPS). The genes responsible for the biosynthesis of the phase variable CPS is located in the hypervariable region of C. jejuni genome which has been used to develop multiplex PCR to classify CPS types based on the Penner serotypes. However, there still are non-typable CPS C. jejuni by the current multiplex PCR scheme. The application of the next generation sequencing and whole genome analysis software were used for the identification of novel capsule biosynthesis of C. jejuni isolates. Unique PCR primers were designed to identify these new capsule biosynthesis loci. The designed primers sets were combined in a new multiplex mix called epsilon. The unique sequences provide an additional information of the biosynthesis loci responsible for some of the common CPS sugars/residues such as heptose, deoxtyheptose and MeOPN among C. jejuni in this new group of CPS multiplex assay. This new primer complements the current C. jejuni multiplex capsule typing system and will help in identifying previously untypeable capsule locus of C. jejuni isolates

Summary of CPS loci from sequenced <i>C</i>. <i>jejuni</i>.

Summary of CPS loci from sequenced C. jejuni.</p

Capsule biosynthesis loci of 20 <i>Campylobacter jejuni</i> clinical isolates from South and South-East Asia and closet relationship to known Penner type.

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Evaluation of in vitro cross-reactivity to avian H5N1 and pandemic H1N1 2009 influenza following prime boost regimens of seasonal influenza vaccination in healthy human subjects: a randomised trial.

Recent studies have demonstrated that inactivated seasonal influenza vaccines (IIV) may elicit production of heterosubtypic antibodies, which can neutralize avian H5N1 virus in a small proportion of subjects. We hypothesized that prime boost regimens of live and inactivated trivalent seasonal influenza vaccines (LAIV and IIV) would enhance production of heterosubtypic immunity and provide evidence of cross-protection against other influenza viruses.In an open-label study, 26 adult volunteers were randomized to receive one of four vaccine regimens containing two doses of 2009-10 seasonal influenza vaccines administered 8 (±1) weeks apart: 2 doses of LAIV; 2 doses of IIV; LAIV then IIV; IIV then LAIV. Humoral immunity assays for avian H5N1, 2009 pandemic H1N1 (pH1N1), and seasonal vaccine strains were performed on blood collected pre-vaccine and 2 and 4 weeks later. The percentage of cytokine-producing T-cells was compared with baseline 14 days after each dose.Subjects receiving IIV had prompt serological responses to vaccine strains. Two subjects receiving heterologous prime boost regimens had enhanced haemagglutination inhibition (HI) and neutralization (NT) titres against pH1N1, and one subject against avian H5N1; all three had pre-existing cross-reactive antibodies detected at baseline. Significantly elevated titres to H5N1 and pH1N1 by neuraminidase inhibition (NI) assay were observed following LAIV-IIV administration. Both vaccines elicited cross-reactive CD4+ T-cell responses to nucleoprotein of avian H5N1 and pH1N1. All regimens were safe and well tolerated.Neither homologous nor heterologous prime boost immunization enhanced serum HI and NT titres to 2009 pH1N1 or avian H5N1 compared to single dose vaccine. However heterologous prime-boost vaccination did lead to in vitro evidence of cross-reactivity by NI; the significance of this finding is unclear. These data support the strategy of administering single dose trivalent seasonal influenza vaccine at the outset of an influenza pandemic while a specific vaccine is being developed.ClinicalTrials.gov NCT01044095

Individual and geometric mean serum haemagglutination inhibition assay, microneutralization assay and serum neuraminidase inhibition assay results against pandemic H1N1 2009 virus in 26 healthy human volunteers measured at baseline and two weeks following each dose of prime boost seasonal influenza vaccination (2 doses administered 8 weeks apart).

<p>Individual and geometric mean serum haemagglutination inhibition assay, microneutralization assay and serum neuraminidase inhibition assay results against pandemic H1N1 2009 virus in 26 healthy human volunteers measured at baseline and two weeks following each dose of prime boost seasonal influenza vaccination (2 doses administered 8 weeks apart).</p

Individual and geometric mean serum haemagglutination inhibition assay, H5pp assay and serum neuraminidase inhibition assay results against avian H5N1 virus in 26 healthy human volunteers measured at baseline and two weeks following each dose of prime boost seasonal influenza vaccination (2 doses administered 8 weeks apart).

<p>Individual and geometric mean serum haemagglutination inhibition assay, H5pp assay and serum neuraminidase inhibition assay results against avian H5N1 virus in 26 healthy human volunteers measured at baseline and two weeks following each dose of prime boost seasonal influenza vaccination (2 doses administered 8 weeks apart).</p

Baseline characteristics in 26 healthy subjects, n (%).

<p>LAIV = live attenuated influenza vaccine; IIV = inactivated influenza vaccination; * as assessed by haemagglutination inhibition, neutralization and neuraminidase inhibition assays.</p