Project description:Influenza A virus reservoirs in animals have provided novel genetic elements leading to the emergence of global pandemics in humans. Most influenza A viruses circulate in waterfowl, but those that infect mammalian hosts are thought to pose the greatest risk for zoonotic spread to humans and the generation of pandemic or panzootic viruses. We have identified an influenza A virus from little yellow-shouldered bats captured at two locations in Guatemala. It is significantly divergent from known influenza A viruses. The HA of the bat virus was estimated to have diverged at roughly the same time as the known subtypes of HA and was designated as H17. The neuraminidase (NA) gene is highly divergent from all known influenza NAs, and the internal genes from the bat virus diverged from those of known influenza A viruses before the estimated divergence of the known influenza A internal gene lineages. Attempts to propagate this virus in cell cultures and chicken embryos were unsuccessful, suggesting distinct requirements compared with known influenza viruses. Despite its divergence from known influenza A viruses, the bat virus is compatible for genetic exchange with human influenza viruses in human cells, suggesting the potential capability for reassortment and contributions to new pandemic or panzootic influenza A viruses.
Project description:Screening of 533 bats for influenza A viruses showed subtype HL18NL11 in intestines of 2 great fruit-eating bats (Artibeus lituratus). High concentrations suggested fecal shedding. Genomic characterizations revealed conservation of viral genes across different host species, countries, and sampling years, suggesting a conserved cellular receptor and wide-ranging occurrence of bat influenza A viruses.
Project description:BackgroundMutations in the PB1 subunit of RNA-dependent RNA polymerase (RdRp) of influenza A virus can affect replication fidelity. Before the influenza A/H1N1 pandemic in 2009, most human influenza A/H1N1 viruses contained the avian-associated residue, serine, at position 216 in PB1. However, near the onset of the 2009 pandemic, human viruses began to acquire the mammalian-associated residue, glycine, at PB1-216, and PB1-216G became predominant in human viruses thereafter.MethodsUsing entropy-based analysis algorithm, we have previously identified several host-specific amino-acid signatures that separated avian and swine viruses from human influenza viruses. The presence of these host-specific signatures in human influenza A/H1N1 viruses suggested that these mutations were the result of adaptive genetic evolution that enabled these influenza viruses to circumvent host barriers, which resulted in cross-species transmission. We investigated the biological impact of this natural avian-to-mammalian signature substitution at PB1-216 in human influenza A/H1N1 viruses.ResultsWe found that PB1-216G viruses had greater mutation potential, and were more sensitive to ribavirin than PB1-216S viruses. In oseltamivir-treated HEK293 cells, PB1-216G viruses generated mutations in viral neuraminidase at a higher rate than PB1-216S viruses. By contrast, PB1-216S viruses were more virulent in mice than PB1-216G viruses. These results suggest that the PB1-S216G substitution enhances viral epidemiological fitness by increasing the frequency of adaptive mutations in human influenza A/H1N1 viruses.ConclusionsOur results thus suggest that the increased adaptability and epidemiological fitness of naturally arising human PB1-216G viruses, which have a canonical low-fidelity replicase, were the biological mechanisms underlying the replacement of PB1-216S viruses with a high-fidelity replicase following the emergence of pdmH1N1. We think that continued surveillance of such naturally occurring PB1-216 variants among others is warranted to assess the potential impact of changes in RdRp fidelity on the adaptability and epidemiological fitness of human A/H1N1 influenza viruses.
Project description:Recently, two genetically distinct influenza viruses were detected in bats in Guatemala and Peru. We conducted influenza A virus surveillance among four bat species in Egypt. Out of 1,202 swab specimens, 105 were positive by real-time PCR. A virus was successfully isolated in eggs and propagated in MDCK cells in the presence of N-tosyl-l-phenylalanine chloromethyl ketone-treated trypsin. Genomic analysis revealed that the virus was phylogenetically distinct from all other influenza A viruses. Analysis of the hemagglutinin gene suggested a common ancestry with other H9 viruses, and the virus showed a low level of cross-reactivity with serum raised against H9N2 viruses. Bats were seropositive for the isolated viruses. The virus replicated in the lungs of experimentally infected mice. While it is genetically distinct, this virus shares several avian influenza virus characteristics suggesting a more recent avian host origin.IMPORTANCE Through surveillance, we isolated and characterized an influenza A virus from Egyptian fruit bats. This virus had an affinity to avian-like receptors but was also able to infect mice. Our findings indicate that bats may harbor a diversity of influenza A viruses. Such viruses may have the potential to cross the species barrier to infect other species, including domestic birds, mammals, and, possibly, humans.
Project description:Influenza A viruses (IAVs) continue to threaten animal and human health globally. Bats are asymptomatic reservoirs for many zoonotic viruses. Recent reports of two novel IAVs in fruit bats and serological evidence of avian influenza virus (AIV) H9 infection in frugivorous bats raise questions about the role of bats in IAV epidemiology. IAVs bind to sialic acid (SA) receptors on host cells, and it is widely believed that hosts expressing both SA α2,3-Gal and SA α2,6-Gal receptors could facilitate genetic reassortment of avian and human IAVs. We found abundant co-expression of both avian (SA α2,3-Gal) and human (SA α2,6-Gal) type SA receptors in little brown bats (LBBs) that were compatible with avian and human IAV binding. This first ever study of IAV receptors in a bat species suggest that LBBs, a widely-distributed bat species in North America, could potentially be co-infected with avian and human IAVs, facilitating the emergence of zoonotic strains.
Project description:We design a cryptographic transistor (cryptoristor)-based true random number generator (tRNG) with low power consumption and small footprint. This is the first attempt to use irregular and unpredictable operation-induced randomness of a cryptoristor as an entropy source. To extract discrete random numbers with a binary code from the cryptoristor, we developed a noise-coupling analog-to-digital converter. This converter not only converts analog signals to digital random bits but also improves the randomness of the entropy source with low power consumption. The randomness of the cryptoristor is attributed to the random carrier multiplications with the creation and stochastic carrier escape as destruction, which occurs iteratively as long as the input current is fed. The cryptoristor-based tRNG passed 15 randomness test suites of NIST Special Publication 800-22. It is robust to iterative operational stresses and to ambient temperature changes, making it an attractive option for hardware-based security solutions in the Internet of Things due to its low power consumption and small size.
Project description:The replication machinery of most RNA viruses lacks proofreading mechanisms. As a result, RNA virus populations harbor a large amount of genetic diversity that confers them the ability to rapidly adapt to changes in their environment. In this work, we investigate whether further increasing the initial population diversity of a model RNA virus can improve adaptation to a single selection pressure, thermal inactivation. For this, we experimentally increased the diversity of coxsackievirus B3 (CVB3) populations across the capsid region. We then compared the ability of these high diversity CVB3 populations to achieve resistance to thermal inactivation relative to standard CVB3 populations in an experimental evolution setting. We find that viral populations with high diversity are better able to achieve resistance to thermal inactivation at both the temperature employed during experimental evolution as well as at a more extreme temperature. Moreover, we identify mutations in the CVB3 capsid that confer resistance to thermal inactivation, finding significant mutational epistasis. Our results indicate that even naturally diverse RNA virus populations can benefit from experimental augmentation of population diversity for optimal adaptation and support the use of such viral populations in directed evolution efforts that aim to select viruses with desired characteristics.