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At least 307 records · Page 17Linked to original sources
PubMed1982

The intermediate host spectrum in a Sarcocystis species of birds.

The life cycle of an avian Sarcocystis has been completed in the laboratory, originating with naturally infected icterids and passing alternately between opossums (Didelphis virginiana) and experimentally infected birds. To determine the intermediate host range, six avian species, including canaries (Serinus canarius), zebra finches (Poephila guttata), budgerigars (Melopsittacus undulatus), pigeons (Columba livia), chickens (Gallus gallus), and guinea fowl (Numida meleagris), were inoculated orally with Sarcocystis sporocysts derived from experimentally infected opossums. All birds but the Galliformes were susceptible to merogony. Pigeons (Columbiformes) were susceptible to early merogony but apparently not to muscle stages. Passeriformes and Psittaciformes were completely susceptible and the parasite developed into muscle cysts in them.

Animals↗
PubMed1993

[Mouse neurovirulence of antigenic chimeras (type I/II) of polioviruses].

The mouse-adapted Lansing strain of poliovirus type 2 PV-2(L) induces fatal poliomyelitis in mice after intracerebral inoculation, while mice inoculated with Mahoney strain of poliovirus type 1 PV-1(M) show no signs of disease. Previous work had indicated that both the 5' non-translated region of the viral genome and the viral capsid protein, neutralization antigenic site I (N-Ag1), were involved in mouse neurovirulence. In order to further explore the role of N-Ag1 in mouse neurovirulence, antigenic chimeras of two poliovirus strains, XF414 and XF324, were constructed. In the two strains, ten amino acids (in XF414) or 16 amino acids (in XF324) in antigenic site I in Vp1 of PV-I (M) were replaced with a PV-2(L)-specific sequences using a mutagenesis cartridge. Mouse neurovirulence tests indicated that mice cerebral inoculated with XF414 and XF324 developed poliomyelitis leading to paralysis or death. The viruses possessing antigenicity of the inoculating viruses were isolated from cerebral tissues of the paralyzed mice. The results demonstrated that N-Ag1 is an important determinant of poliovirus host range, and may be involved in attachment and penetration of poliovirus (in)to cells of the mouse central nervous system.

Animals↗
PubMed2001

Host range of small-ruminant lentivirus cytopathic variants determined with a selectable caprine arthritis- encephalitis virus pseudotype system.

The small-ruminant lentiviruses ovine maedi-visna virus (MVV) and caprine arthritis-encephalitis virus (CAEV) cause encephalitis, progressive pneumonia, arthritis, and mastitis in sheep and goats. Icelandic MVV strains, which are lytic in tissue culture, have a wide species distribution of functional receptors, which includes human cells. In contrast, functional receptors for the nonlytic CAEV CO are absent from human cells. To determine if the wide species distribution of functional receptors is a common property of MVV strains or related to cytopathic phenotype, we tested the infectivity of viruses pseudotyped with the envelope glycoproteins of MVV K1514, CAEV CO, and lytic and nonlytic North American MVV strains to cells of different species. Replication-defective CAEV proviral constructs lacking the env, tat, and vif genes and carrying the neomycin phosphotransferase gene in the vif-tat region were developed for the infectivity assays. Cotransfection of human 293T cells with these proviral constructs and plasmids expressing CAEV, MVV, or vesicular stomatitis virus envelope glycoproteins produced infectious pseudotyped virus which induced resistance of infected cells to G418. Using these pseudotypes, we confirmed the wide species distribution of Icelandic MVV receptors and the narrow host range of CAEV. However, functional receptors for the two North American MVV strains tested, unlike the Icelandic MVV and similar to CAEV, were limited to cells of ruminant species, regardless of cytopathic phenotype. The results indicate a differential receptor recognition by MVV strains which is unrelated to cytopathic phenotype.

Amino Acid Sequence↗
PubMed2001

Construction and initial characterization of an infectious plasmid clone of a newly identified hamster parvovirus.

The construction and characterization of a full-length infectious plasmid clone of the newly identified hamster parvovirus (HaPV) are described. Following transfection of hamster BHK cells with the infectious clone, pHaPV, the specific intracellular DNA replicative forms, RNA transcripts and viral proteins that were expected for this rodent parvovirus were generated. Infected cells were lysed and progeny virus was produced, demonstrating that pHaPV could generate a productive virus infection. The complete sequences of both hairpin termini, which had not been previously determined, were obtained. Preliminary host-range studies, which compared virus production and macromolecular synthesis in various cell lines following either HaPV infection or pHaPV transfection, demonstrated an early block of infection of HaPV in both monkey COS-1 and murine A9 cells. The availability of an HaPV infectious clone will facilitate its genetic analysis and allow the elucidation of the determinants important in host range, tissue tropism and pathogenicity of this newly identified rodent parvovirus.

Animals↗
PubMed1989

Genetic definition of two functional elements in a bacteriophage T4 host-range "cassette".

Gene 37 of T4 encodes the major subunit of the distal half of the tail fiber. The distal tip of the fiber, comprised of the carboxy-terminal ends of two molecules of gene 37 product (gp37), carries the principal determinant of the phage host range. The gp37 carboxyl termini recognize the bacterial surface during infection, and, in addition, include a site required for interaction with the product of gp38 during distal half-fiber assembly. In the absence of interaction with gp38, gp37 polypeptides do not dimerize. Eleven temperature-sensitive mutants with defects located near the promoter-distal end of gene 37 were tested at nonpermissive temperatures for production of an antigen that is diagnostic of distal half-fiber assembly. Six of the mutations prevent distal half-fiber assembly. The other five allow assembly of distal half fibers, which combine with proximal half fibers and attach to phage particles, but the resulting phage do not adsorb to bacteria. These two classes of mutations define two adjacent but separate genetic regions, corresponding to two different functional domains in gp37. These two regions and the neighboring gene 38 comprise a functional unit that can be considered as a host-range "cassette," with features that are strikingly similar to corresponding functional units in other unrelated as well as related phages.

Antigens, Viral↗
PubMed1996

Tomato golden mosaic virus open reading frame AL4 is genetically distinct from its C4 analogue in monopartite geminiviruses.

Tomato golden mosaic virus (TGMV) is a bipartite geminivirus with six well-characterized genes. An additional open reading frame (ORF), AL4, lies within the essential AL1 gene. Recent studies of monopartite, dicot-infecting geminiviruses have revealed that mutations in their analogous C4 ORFs have host-specific effects on infectivity, symptomatology, virus movement and/or viral DNA accumulation. We have investigated whether TGMV has a similar host-specific requirement for AL4. The phenotypes of three TGMV al4 mutants were determined in a range of hosts, which included species that revealed c4 mutant phenotypes for monopartite geminiviruses. Each TGMV al4 mutant was indistinguishable from wild-type TGMV in all hosts tested. Additional analyses of double mutants revealed no evidence for functional redundancy between AL4 and the AL3, or AR1 genes. In contrast to the putative C4 proteins of monpartite geminiviruses, TGMV AL4, if it is expressed, is either non-functional, or functionally redundant with an essential TGMV gene product.

Base Sequence↗
PubMed2002

The active partition gene incC of IncP plasmids is required for stable maintenance in a broad range of hosts.

Plasmids of incompatibility group P (IncP) are capable of replication and stable inheritance in a wide variety of gram-negative bacteria. Three determinants of IncP plasmids are components of an active partition locus that is predicted to function in the segregation of plasmid copies to daughter cells. These determinants are incC, which codes for a member of the ParA family of partition ATPases; korB, which specifies a DNA-binding protein that also functions as a global transcriptional repressor; and O(B), the DNA target for KorB, which occurs at multiple locations on IncP plasmids. To determine the importance and host range of the IncC/KorB partition system in the maintenance of IncP plasmids, we constructed an in-frame deletion of incC in the otherwise intact 60-kb IncP alpha plasmid R995. R995 Delta incC was found to be highly unstable in Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, Agrobacterium tumefaciens, and Acinetobacter calcoaceticus, whereas wild-type R995 is stable in all these hosts. In addition, R995 Delta incC could not be established in Actinobacillus actinomycetemcomitans. trans-Complementation analysis showed that the coding region for IncC2 polypeptide, which is expressed from an internal translational start within the incC gene, was sufficient to restore stable maintenance to wild-type levels. The results show that the IncC/KorB active partition system of IncP plasmids is remarkably proficient for stable maintenance in diverse bacteria.

Bacterial Proteins↗
PubMed1994

Characterization of the feline host range and a specific epitope of feline panleukopenia virus.

The feline parvovirus subgroup is comprised of viruses isolated from various carnivores, including the dog, cat, mink, raccoon, Arctic fox, and raccoon dog. Those viruses are > 98% identical in their DNA sequences and are very similar antigenically. We have shown that although canine parvovirus (CPV) replicates in numerous feline cell lines in vitro it does not infect cats after parenteral inoculation (U. Truyen and C. R. Parrish, (1992) J. Virol. 66, 5399-5408). Here we use recombination mapping to locate some viral determinants required for feline host range, and show that the ability to replicate in cats was determined by the right-hand 45% of the genome, most likely a function of the capsid protein gene. Efficient replication in the cat appeared to require feline panleukopenia virus sequences from both ends of the VP2 molecule, which contained differences of VP2 amino acid residues 80, 564, and 568. The difference at amino acid 80 was also associated with expression of an FPV-specific antigenic epitope. The differences which affected the feline host range were located in a region of the capsid structure where three VP2 molecules interact, and the mutations gave rise to changes in the conformation of loops of the three adjoining VP2 monomers. The mechanism(s) of the in vivo feline host range restriction were not defined, and we were unable to show in vitro inhibition of virus infectivity by feline serum components or erythrocytes.

Animals↗
PubMed1994

Regulation of susceptibility and cell surface receptor for the B-lymphotropic papovavirus by N glycosylation.

The host range of the B-lymphotropic papovavirus (LPV) in cultured human cells is limited to a few B-lymphoma-derived cell lines. The constitutively expressed cell surface receptor for the virus is a major determinant restricting the LPV host range (G. Haun, O. T. Keppler, C. T. Bock, M. Herrmann, H. Zentgraf, and M. Pawlita, J. Virol. 67:7482-7492, 1993). Here we show that human B-lymphoma cells with low-level susceptibility are rendered highly susceptible to LPV infection by pretreatment with the N glycosylation inhibitor tunicamycin but remain nonsusceptible to infection by the related polyomavirus simian virus 40. Among the selective N glycosylation processing inhibitors, deoxymannojirimycin, but not deoxynojirimycin, swainsonine, or castanospermine, could mimic the effect of tunicamycin. Tunicamycin treatment also induced a drastic enhancement of the cells' LPV-binding capacity, indicating that the induction of LPV susceptibility might be mediated by an increase in the number of functional cell surface receptors and/or by increased receptor affinity. Sialidase sensitivity of the tunicamycin-induced LPV receptor showed that oligosaccharides carrying terminal sialic acids are necessary for binding and are likely to be O linked. The constitutive LPV receptor is also sialic acid dependent, which points to a possible identity with the sialic acid-dependent tunicamycin-induced LPV receptor. We conclude that removal or modification of certain N-linked oligosaccharides in human B-lymphoma cells can enhance expression or functional activity of the sialylated LPV receptor.

B-Lymphocytes↗
PubMed2003

Infection success in novel hosts: an experimental and phylogenetic study of Drosophila-parasitic nematodes.

Surprisingly little is known about what determines a parasite's host range, which is essential in enabling us to predict the fate of novel infections. In this study, we evaluate the importance of both host and parasite phylogeny in determining the ability of parasites to infect novel host species. Using experimental lab assays, we infected 24 taxonomically diverse species of Drosophila flies (Diptera: Drosophilidae) with five different nematode species (Tylenchida: Allantonematidae: Howardula, Parasitylenchus), and measured parasite infection success, growth, and effects on female host fecundity (i.e., virulence). These nematodes are obligate parasites of mushroom-feeding Drosophila, particularly quinaria and testacca group species, often with severe fitness consequences on their hosts. We show that the potential host ranges of the nematodes are much larger than their actual ranges, even for parasites with only one known host species in nature. Novel hosts that are distantly related from the native host are much less likely to be infected, but among more closely related hosts, there is much variation in susceptibility. Potential host ranges differ greatly between the related parasite species. All nematode species that successfully infected novel hosts produced infective juveniles in these hosts. Most novel infections did not result in significant reductions in the fecundity of female hosts, with one exception: the host specialist Parasitylenchus nearcticus sterilized all quinaria group hosts, only one of which is a host in nature. The large potential host ranges of these parasites, in combination with the high potential for host colonization due to shared mushroom breeding sites, explain the widespread host switching observed in comparisons of nematode and Drosophila phylogenies.

Animals↗
PubMed1970

Host-range restrictions of murine leukemia viruses in mouse embryo cell cultures.

Murine leukemia virus strains fall into three categories with respect to their ability to propagate in cells of National Institutes of Health (NIH) Swiss and BALB/c mouse embryos. Cultures of NIH cells are 100- to 1,000-fold more sensitive to "N-tropic" strains than BALB/c cell cultures, but are 30- to 100-fold less sensitive to "B-tropic" strains. Some virus strains (dually tropic or "NB-tropic") propagate equally well in both cells. M-MSV pseudotypes show the host-range characteristics of the virus supplying the envelope, both in vitro and in vivo. The host-range characteristics appear to be genetically determined and could not be explained by host-induced modification or virus mixtures. There was no correlation between host range and Gross-AKR or FMR serotype.

Animals↗
PubMed2004

Influenza A viruses of migrating wild aquatic birds in North America.

Surveillance of North America's wild ducks and shorebirds for 26 and 16 years, respectively, revealed differences in the prevalence of orthomyxoviruses between these hosts. Shorebirds had a high frequency of influenza A virus isolation during their northern migration, while wild ducks had high virus isolation frequencies during their southern migration. Some subtypes of influenza occurred regularly in both hosts with a 2-year periodicity, whereas others rarely occurred. Hemagglutinin subtypes H1 through H12 occurred in both hosts; H13 occurred only in shorebirds; and H14, H15, and influenza B and C never were detected. Shorebirds manifested a broader range of subtypes suggesting that shorebirds are the leading source of some viruses (such as H5) which are isolated less frequently from wild ducks. The viruses reported in this study are available for genomic study to determine whether prediction of host range or pandemic potential is possible.

Animal Migration↗
PubMed1984

Molecular analysis of the envelope gene and long terminal repeat of Friend mink cell focus-inducing virus: implications for the functions of these sequences.

We sequenced the envelope (env) gene and 3' long terminal repeat of a Friend mink cell focus-inducing virus (F-MCFV). We also sequenced the gp70 coding regions for two cDNA clones of another F-MCFV. The deduced amino acid sequence of the env gene products of both F-MCFVs were compared to the corresponding sequences of other MCFVs and of ecotropic viruses. The env polypeptides of the different viruses showed long stretches of homology in the carboxy-terminal half of gp70 and in p15env ("constant region"). The amino-terminal half of gp70 was very similar in all MCFVs, but showed extensive variations relative to the ecotropic viruses ("differential region"). This differential region in all MCFVs is of endogeneous origin. We show evidence that this region carries determinants for ecotropic or polytropic host range. No indication could be found that the env gene products determine the histological type of disease caused by particular MCFVs. When the long terminal repeats of F-MCFV and Friend murine leukemia virus were compared with those of other viruses causing either lymphatic leukemia or erythroleukemia, several nucleotides were localized which might determine the histological type of disease caused by these viruses.

Amino Acid Sequence↗
PubMed1991

Envelope glycoproteins from biologically diverse isolates of immunodeficiency viruses have widely different affinities for CD4.

The envelope glycoprotein gp120 of primate immunodeficiency viruses initiates viral attachment to CD4+ cells by binding to the CD4 antigen on host cell surfaces. However, among different CD4+ cell types, different viruses display distinct host cell ranges and cytopathicities. Determinants for both of these biological properties have been mapped to the env gene. We have quantitatively compared the CD4 binding affinities of gp120 proteins from viruses exhibiting different host cell tropisms and cytopathicities. The viral proteins were produced by using a Drosophila cell expression system and were purified to greater than 90% homogeneity. Drosophila-produced gp120 from T-cell tropic human immunodeficiency virus type 1 (HIV-1) BH10 exhibits binding to soluble recombinant CD4 (sCD4) and syncytia inhibition potency identical to that of pure authentic viral gp120. Relative to the affinity of HIV-1 BH10 gp120 for sCD4, that of dual tropic HIV-1 Ba-L is 6-fold lower, that of restricted T-cell tropic simian immunodeficiency virus mac is 70-fold lower, and that of noncytopathic HIV-2 ST is greater than 280-fold lower. Thus, viruses that utilize CD4 for infection do so by using a remarkably wide range of envelope affinities. These differences in affinity may play a role in determining cell tropism and cytopathicity.

Amino Acid Sequence↗
PubMed2003

Reproductive response of generalist and specialist aphid morphs with the same genotype to plant secondary compounds and amino acids.

Many studies have paid particular attention to the role of either secondary plant compounds or amino acids as determinants of host-plant range in phytophagous insects. Here we examine the relative importance of both of these classes of compound in host acceptance by generalist and specialist morphs of the black bean aphid, Aphis fabae, that are morphologically similar and genetically identical. Eleven secondary plant compounds and six amino acids with known biological activity in aphids are presented to insects within an artificial membrane system as single compounds, mixtures of same-class compounds and combined mixtures of the two classes of compound. It is found that 1) when specific single secondary compounds and amino acids are presented to generalist and specialist morphs of A. fabae, differential responses are exclusively consistent with plant-use strategy for amino acids but not for secondary compounds, 2) neither secondary compound nor amino acid mixtures give reproductive responses entirely consistent with plant range, but the response to secondary compounds is broadly consistent with plant range whereas the response to amino acids is not, 3) when secondary compounds and amino acid mixtures are combined, the response to secondary compounds generally dominates that to amino acids. Some scenarios of plant-range determination by secondary plant compounds and amino acids, suggested by results, are discussed.

Amino Acids↗
PubMed1992

A self-transmissible, narrow-host-range endogenous plasmid of Rhodobacter sphaeroides 2.4.1: physical structure, incompatibility determinants, origin of replication, and transfer functions.

Rhodobacter sphaeroides 2.4.1 naturally harbors five cryptic endogenous plasmids (C. S. Fornari, M. Watkins, and S. Kaplan, Plasmid 11:39-47, 1984). The smallest plasmid (pRS241e), with a molecular size of 42 kb, was observed to be a self-transmissible plasmid which can transfer only to certain strains of R. sphaeroides. Transfer frequencies can be as high as 10(-2) to 10(-3) per donor under optimal mating conditions in liquid media in the absence of oxygen. pRS241e, designated the S factor, was also shown to possess a narrow host range, failing either to replicate or to be maintained in Escherichia coli, Agrobacterium tumefaciens, and Rhizobium meliloti. It was further revealed that one of the remaining four endogenous plasmids, pRS241d, was also transmissible at a frequency similar to that of the S. factor. As a cointegrate with pSUP203, S was maintained in E. coli, providing sufficient DNA from which a physical map of S could be constructed. Progressive subcloning of S-factor DNA, in conjunction with assays of plasmid transfer, led to the localization and identification of oriV (IncA), IncB, and the putative oriT locus. The DNA sequence of the 427 bp containing oriTs revealed topological similarity to other described oriT sequences, consisting of an A-T-rich DNA region, several direct and inverted repeats, and putative integration host factor (IHF)-binding sites, and was shown to be functional in promoting plasmid transfer.

Anaerobiosis↗
PubMed1996

Structural determination of symbiotic nodulation factors from the broad host-range Rhizobium species NGR234.

Nod factors are secreted lipo-oligosaccharides produced by symbiotic nitrogen-fixing Rhizobium bacteria that induce nodule formation on the roots of host leguminous plants. Two biologically active fractions (NodNGRA and NodNGRB) were isolated by reversed-phase HPLC from the culture supernatant of a Nod factor overproducing strain of Rhizobium sp. NGR234. NodNGRA and NodNGRB are heterogeneous mixtures of N-acylated 2-O-methylfucosylated chitomers, in which the fucosyl residue may be either 3-sulfated (NodNGRA), or 4-O-acetylated or nonsubstituted (NodNGRB). Structurally analogous series of compounds occur with either N-vaccenic (C18:1) or N-palmitic (C16:0) substituents. The presence of 6-O-carbamoyl groups on the GlcNMe-Acyl residue occurs on some molecules, while others are di-O-carbamoylated. Detailed structural analysis of seventeen Nod factors are reported here.

Carbohydrate Sequence↗