Summary
Infections with influenza A viruses result in the activation of a variety of intracellular signalling pathways. Recent findings suggest that in response to double‐stranded RNA (dsRNA), which ...is commonly used as a mimic for accumulating viral RNA, the phosphatidylinositol‐3‐kinase (PI3K) is activated and mediates activation of the transcription factor interferon regulatory factor 3 (IRF‐3). Thus, we investigated the function of PI3K during influenza virus infection. The pathway was activated upon infection and consistent with earlier findings using dsRNA, inhibition of PI3K itself or block of signalling by the PI3K product, the second messenger phosphatidylinositol‐3,4,5‐trisphosphate (PIP3), results in misphosphorylation and impaired dimerization of IRF‐3 as well as reduced IRF‐3‐dependent promoter activity. This would imply an antiviral function of the kinase in influenza virus‐infected cells. However, upon inhibition of PI3K, titers of progeny virus were reduced rather than enhanced. This was coincident with a strong decrease of viral protein accumulation that was not due to a block of protein synthesis or inhibition of the viral polymerase complex. Immunofluorescence studies revealed that PI3K rather appears to regulate a very early step during viral entry. Thus PI3K is a perfect example of a seemingly antiviral signalling component that is misused by the virus to support effective replication.
During January 28-May 5, 2019, a meningitis outbreak caused by Neisseria meningitidis serogroup C (NmC) occurred in Burkina Faso. Demographic and laboratory data for meningitis cases were collected ...through national case-based surveillance. Cerebrospinal fluid was collected and tested by culture and real-time PCR. Among 301 suspected cases reported in 6 districts, N. meningitidis was the primary pathogen detected; 103 cases were serogroup C and 13 were serogroup X. Whole-genome sequencing revealed that 18 cerebrospinal fluid specimens tested positive for NmC sequence type (ST) 10217 within clonal complex 10217, an ST responsible for large epidemics in Niger and Nigeria. Expansion of NmC ST10217 into Burkina Faso, continued NmC outbreaks in the meningitis belt of Africa since 2019, and ongoing circulation of N. meningitidis serogroup X in the region underscore the urgent need to use multivalent conjugate vaccines in regional mass vaccination campaigns to reduce further spread of those serogroups.
The human pathogens
and
share high genome identity. Retrospective analysis of surveillance data from New Zealand indicates the potential cross-protective effect of outer membrane vesicle (OMV) ...meningococcal serogroup B vaccine (MeNZB) against
A licensed OMV-based MenB vaccine, MenB-4C, consists of a recombinant FHbp, NhbA, NadA, and the MeNZB OMV. Previous work has identified several abundantly expressed outer membrane proteins (OMPs) as major components of the MenB-4C OMV with high sequence similarity between
and
, suggesting a mechanism for cross-protection. To build off these findings, we performed comparative genomic analysis on 970 recent
isolates collected through a U.S surveillance system against
serogroup B (NmB) reference sequences. We identified 1,525 proteins that were common to both
species, of which 57 proteins were predicted to be OMPs using
methods. Among the MenB-4C antigens, NhbA showed moderate sequence identity (73%) to the respective gonococcal homolog, was highly conserved within
, and was predicted to be surface expressed. In contrast, the gonococcal FHbp was predicted not to be surface expressed, while NadA was absent in all
isolates. Our work confirmed recent observations (E. A. Semchenko, A. Tan, R. Borrow, and K. L. Seib, Clin Infect Dis, 2018, https://doi.org/10.1093/cid/ciy1061) and describes homologous OMPs from a large panel of epidemiologically relevant
strains in the United States against NmB reference strains. Based on our results, we report a set of OMPs that may contribute to the previously observed cross-protection and provide potential antigen targets to guide the next steps in gonorrhea vaccine development.
Gonorrhea, a sexually transmitted disease, causes substantial global morbidity and economic burden. New prevention and control measures for this disease are urgently needed, as strains resistant to almost all classes of antibiotics available for treatment have emerged. Previous reports demonstrate that cross-protection from gonococcal infections may be conferred by meningococcal serogroup B (MenB) outer membrane vesicle (OMV)-based vaccines. Among 1,525 common proteins shared across the genomes of both
and
, 57 proteins were predicted to be surface expressed (outer membrane proteins OMPs) and thus preferred targets for vaccine development. The majority of these OMPs showed high sequence identity between the 2 bacterial species. Our results provide valuable insight into the meningococcal antigens present in the current OMV-containing MenB-4C vaccine that may contribute to cross-protection against gonorrhea and may inform next steps in gonorrhea vaccine development.
Human infections by avian influenza A(H7N9) virus entail substantial morbidity and mortality. Treatment of infected patients with the neuraminidase (NA) inhibitor oseltamivir was associated with ...emergence of viruses carrying NA substitutions. In the NA inhibition (NI) assay, R292K conferred highly reduced inhibition by oseltamivir, while E119V and I222K each caused reduced inhibition. To facilitate establishment of laboratory correlates of clinically relevant resistance, experiments were conducted in ferrets infected with virus carrying wild-type or variant NA genes recovered from the A/Taiwan/1/2013 isolate. Oseltamivir treatment (5 or 25 mg/kg of body weight/dose) was given 4 h postinfection, followed by twice-daily treatment for 5 days. Treatment of ferrets infected with wild-type virus resulted in a modest dose-dependent reduction (0.7 to 1.5 log10 50% tissue culture infectious dose TCID50) in nasal wash viral titers and inflammation response. Conversely, treatment failed to significantly inhibit the replication of R292K or E119V virus. A small reduction of viral titers was detected on day 5 in ferrets infected with the I222K virus. The propensity for oseltamivir resistance emergence was assessed in oseltamivir-treated animals infected with wild-type virus; emergence of R292K virus was detected in 3 of 6 ferrets within 5 to 7 days postinfection. Collectively, we demonstrate that R292K, E119V, and I222K reduced the inhibitory activity of oseltamivir, not only in the NI assay, but also in infected ferrets, judged particularly by viral loads in nasal washes, and may signal the need for alternative therapeutics. Thus, these clinical outcomes measured in the ferret model may correlate with clinically relevant oseltamivir resistance in humans.
This report provides more evidence for using the ferret model to assess the susceptibility of influenza A(H7N9) viruses to oseltamivir, the most prescribed anti-influenza virus drug. The information gained can be used to assist in the establishment of laboratory correlates of human disease and drug therapy. The rapid emergence of viruses with R292K in treated ferrets correlates well with the multiple reports on this NA variant in treated human patients. Our findings highlight the importance of the discovery and characterization of new antiviral drugs with different mechanisms of action and the use of combination treatment strategies against emerging viruses with pandemic potential, such as avian H7N9 virus, particularly against those carrying drug resistance markers.
Human infections caused by avian influenza A virus type subtype H7N9 have been associated with substantial morbidity and mortality. Emergence of virus variants carrying markers of decreased ...susceptibility to neuraminidase inhibitors was reported. Here we show that DAS181 (Fludase), an antiviral drug with sialidase activity, potently inhibited replication of wild-type influenza A(H7N9) and its oseltamivir-resistant R292K variants in mice. A once-daily administration initiated early after lethal infection hampered body weight loss and completely protected mice from lethality. We observed a time-dependent effect for 24-72-hour delayed DAS181 treatments on morbidity and mortality. The results warrant further investigation of DAS181 for influenza treatment.
Background. Patients contracting influenza A(H7N9) infection often developed severe disease causing respiratory failure. Neuraminidase (NA) inhibitors (NAIs) are the primary option for treatment, but ...information on drug-resistance markers for influenza A(H7N9) is limited. Methods. Four NA variants of A/Taiwan/1/2013(H7N9) virus containing a single substitution (NA-E119V, NAI222K, NA-I222R, or NA-R292K) recovered from an oseltamivir-treated patient were tested for NAI susceptibility in vitro; their replicative fitness was evaluated in cell culture, mice, and ferrets. Results. NA-R292K led to highly reduced inhibition by oseltamivir and peramivir, while NA-E119V, NA-I222K, and NA-I222R caused reduced inhibition by oseltamivir. Mice infected with any virus showed severe clinical signs with high mortality rates. NA-I222K virus was the most virulent in mice, whereas virus lacking NA change (NAWT) and NA-R292K virus seemed the least virulent. Sequence analysis suggests that PB2-S714N increased virulence of NA-I222K virus in mice; NS1-K126R, alone or in combination with PB2-V227M, produced contrasting effects in NA-WT and NA-R292K viruses. In ferrets, all viruses replicated to high titers in the upper respiratory tract but produced only mild illness. NA-R292K virus, showed reduced replicative fitness in this animal model. Conclusions. Our data highlight challenges in assessment of the replicative fitness of H7N9 NA variants that emerged in NAI-treated patients.
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