PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “host range”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1996

Host range restricted, non-replicating vaccinia virus vectors as vaccine candidates.

Three model systems were used to demonstrate the immunogenicity of highly attenuated and replication-defective recombinant MVA. (1) Intramuscular inoculation of MVA-IN-Fha/np induced humoral and cell-mediated immune responses in mice and protectively immunized them against a lethal respiratory challenge with influenza virus. Intranasal vaccination was also protective, although higher doses were needed. (2) In rhesus macaques, an immunization scheme involving intramuscular injections of MVA-SIVenv/gag/pol greatly reduced the severity of disease caused by an SIV challenge. (3) In a murine cancer model, immunization with MVA-beta gal prevented the establishment of tumor metastases and even prolonged life in animals with established tumors. These results, together with previous data on the safety of MVA in humans, suggest the potential usefulness of recombinant MVA for prophylactic vaccination and therapeutic treatment of infectious diseases and cancer.

Animals↗
PubMed1977

Physical and genetic studies with restriction endonucleases on the broad host-range plasmid RK2.

The cleavage map of the plasmid RK2 was determined for the five restriction endonucleases EcoRI, HindIII, BamH-I, SalI and HpaI. DNA has been inserted into several of these sites and cloned in Escherichia coli. Efforts to obtain derivatives of RK2 reduced in size by restriction endonuclease digestion of the plasmid were not successful and indicated that genes required for the maintenance of this plasmid in E. coli are not tightly clustered. An RK2 derivative possessing an internal molecular rearrangement was obtained by transformation with restriction endonuclease digests of the plasmid.

DNA Replication↗
PubMed1986

Control of replication of the broad host range plasmid RSF1010: the incompatibility determinant consists of directly repeated DNA sequences.

A 500 bp DNA fragment located in the vicinity of the origin of replication of plasmid RSF1010 was cloned into the plasmid vector pBR322 and shown to exhibit incompatibility against parental RSF1010. The rightmost region of this fragment contains three perfect 20 bp direct repeats and a fourth half-repeat of 11 bp, as shown by DNA sequencing. Deletion of the four repeats from the cloned fragment resulted in complete loss of incompatibility whereas partial deletion of the repeated sequence resulted in a concurrent decrease in the expression of incompatibility. We conclude that the incompatibility determinant of RSF1010 is defined by the four repeats and also that the incompatibility expressed is not very strong, since the presence of about 1.5 times as many copies of the repeated sequence as are normally in a cell does not cause a total switch off of RSF1010 replication, but only a 40% reduction in the rate of replication.

DNA Replication↗
PubMed1988

Integrative suppression of dnaA46 by broad host-range plasmid R1162.

Replication of plasmid R1162 DNA does not require the product of the dnaA gene. An integrated copy of the plasmid can suppress the temperature-sensitive dnaA46 allele when (1) additional plasmid copies are present in the cytoplasm and (2) an inactive replication origin, generated by deletion, is also present in the chromosome. We propose that the inactive origin sets the rate of initiation of chromosome replication at a level compatible with cell viability, possibly by providing additional binding sites for an R1162-encoded protein that is rate-limiting for plasmid replication.

Bacterial Proteins↗
PubMed1988

Host range of avian influenza virus in free-living birds.

Isolation of avian influenza virus (AIV) has been reported from 12 orders and 88 species of free-living birds. Most isolations are reported from species in the orders Anseriformes and Charadriiformes and it is recognized that species in Anseriformes represent important reservoirs of AIV. Morbidity and mortality among free-living birds attributable to AIV infection are rare, but differences in prevalence of AIV occur within and between avian species. Seasonal variation has been reported from free-living and sentinel ducks with peak AIV infection occurring in late summer and early fall. Prevalence of AIV is age-related, with highest isolation rates reported from juvenile birds. Differences in susceptibility to AIV infection among species have been demonstrated under experimental conditions. The dynamics and epidemiology of species-related variation in populations of free-living birds require further study.

Aging↗
PubMed1996

Host-range restriction of vaccinia virus E3L-specific deletion mutants.

The vaccinia virus (VV) E3L gene product functions as a dsRNA binding protein that is involved in conferring an interferon-resistant phenotype upon the virus. Studies with a vaccinia virus (VV) E3L- deletion mutant (vP1080) have also demonstrated that the E3L gene product is critical for productive replication on certain cell substrates. While E3L was found to be nonessential for replication in chick embryo fibroblasts (CEFs), virus specifically deleted of E3L was found to be replication deficient in Vero, HeLa, and murine L929 cells. Further, the temporal block in replication appears to differ in these cell systems, as evidenced by the observed timing of protein synthesis inhibition. In Vero cells infected with the VV E3L- mutant, there was no detectable protein synthesis after 2 hr post-infection, whereas in L929 cells normal protein patterns were observed even at late times post-infection. Expression of a heterologous dsRNA binding protein, the reovirus sigma 3 protein, by the E3L- mutant virus restored near wild-type growth characteristics, suggesting the critical nature for regulating dsRNA levels in VV-infected cells.

Animals↗
PubMed1984

Construction of a gene bank of Rhodopseudomonas capsulata using a broad host range DNA cloning system.

A gene bank of the phototrophic bacterium Rhodopseudomonas capsulata was constructed using the binary plasmid system pRK290/pRK2013. Fragments of about 20 kb of chromosomal DNA of R. capsulata strain 37b4 were inserted into the cloning vector pRK290. The hybrid plasmids of the gene bank, maintained in Escherichia coli HB101 were transferred by conjugation to R. capsulata strains defective in the photosynthetic apparatus with frequencies of 5 X 10(-4) to 5 X 10(-2). Phototrophically growing transconjugants occurred with frequencies of 5 X 10(-7) to 5 X 10(-6). Recombination between the hybrid plasmids and the R. capsulata chromosome was shown. The hybrid plasmid pRCF1002, carrying a 25 kb insert of R. capsulata wild type DNA, was isolated from one E. coli clone of the gene bank. It reconstituted some bacteriochlorophyll- and photosynthetic negative mutants to phototrophic growth.

Cloning, Molecular↗
PubMed1978

Characterization of a Sinbis virus variant with altered host range.

A variant of Sindbis virus which is much more infectious for mouse cells than the standard virus has been examined for biochemical properties which might be responsible for this biological difference. The variant has a much enhanced ability to adsorb to mouse plasmacytoma (MOPC 315) cells, but when these cells were pretreated with heparin, they were able to adsorb the standard virus almost as well as the variant. This suggested that there was a surface charge difference between variant and standard virus. Differential elution of the viruses from hydroxyapatite and the results of isoelectric focusing of the virion glycoproteins substantiate this interpretation. Both viral glycoproteins E1 and E2 from the variant were more negatively charged than those of the standard virus but we were unable to find changes in tryptic peptides of the variant. Differences were found in stability of the two virus strains to heat and proteolytic enzymes.

Adsorption↗
PubMed1978

Host range mutants of an influenza A virus.

Temperature-sensitive (ts) mutants of fowl plague virus with a ts-lesion in segment 1 (ts 3, polymerase 1 gene) or segment 2 (ts 90, transport gene) do not form plaques on MDCK cells at the permissive temperature, while the wild type and ts-mutants of other groups are able to do so. This property is correlated with the ts-lesion, since revertants for the ts-lesion of ts 3 and ts 90 again form plaques on MDCK cells. The block on MDCK cells--at least for ts3--may be located in a late function, since viral RNA polymerase and hemagglutinin are formed in almost normal yields. MDCK cells infected with ts 3 or ts 90 exhibit a retarded cytopathic effect at 33 degrees C, but no cytopathic effect at 39 degrees C, at which temperature the infected cells can be passaged and super-infected with the wild type strain. Cells surviving the infection with ts 90 at 33 degrees C sometimes grow out again to a normal monolayer. It is suggested that the spread of virus is inhibited under these conditions.

Cell Line↗