Biomedical subjects

C Letellier

Publications and source records attributed to C Letellier.

41 records · Page 3Linked to original sources

PubMed1991

Construction of a pigeonpox virus recombinant: expression of the Newcastle disease virus (NDV) fusion glycoprotein and protection of chickens against NDV challenge.

A pigeonpox transfer plasmid was constructed by cloning a 2.5 kb DNA fragment containing the viral thymidine kinase (TK) gene in the psp65 plasmid. The vaccinia virus P11K promoter followed by the NDV fusion (F) gene was inserted in the TK gene. The F gene was transferred to the viral genome by homologous recombination in pigeonpox virus infected CEF cells, transfected with the recombinant plasmid. Recombinant viruses were selected with BUdR and screened for their ability to induce fusion between adjacent cells. Because of the unexpected growth advantage of the TK+ WT over the TK- recombinants, viral purification was needed to obtain stable recombinants expressing a glycosylated and cleaved F protein. Vaccination of chickens by the follicular method induced high anti-F antibody titers and good protection against challenge with the virulent Italian NDV strain. Half of the oculonasal vaccinated chickens showed anti F antibodies and also half of them were protected. Although protection seems to be correlated with antibody titers, no neutralizing antibodies were found.

Animals↗

PubMed1991

The influence of cryopreservation on activity and surface markers of lymphokine-activated killer cells.

Ficoll-separated and monocyte-depleted mononuclear cells isolated from normal leukapheresis products were cryopreserved. These cells were incubated with or without 1,000 U/ml of recombinant interleukin-2 (rIL-2) for 4 days, and their lymphokine-activated killer (LAK) and natural killer (NK) activities were measured. IL-2 activation induced a significant increase in the expression of the CD25 antigen. There was no change in CD2, CD3, CD4, CD8, CD16, CD56 and CD57 cell marker expression. Cryopreservation did not induce any change in the membrane antigen expression and in the lymphocyte subsets. The NK activity was well preserved and the decrease of LAK activity of IL-2-activated cells after cryopreservation was not significant. In contrast, cells activated before cryopreservation had a significantly lower cytotoxic activity and the number of cells expressing the IL-2 receptor was also significantly reduced. However, the decrease of CD56 expression was not significant. CD25 expression seemed to be proportional to the LAK activity of the cells. This study demonstrated that cryopreserved lymphocytes, after 4 days of culture with rIL-2, could be as active and could express the CD25 and CD56 cell surface markers in the same manner as fresh LAK cells.

Antigens, CD↗

PubMed1989

Expression of the bovine leukemia virus transactivator protein p34 by a recombinant vaccinia virus.

In order to characterize the bovine leukemia virus transactivator protein, a recombinant vaccinia virus (v-LOR) containing the BLV post-envelope long open reading frame was constructed. v-LOR was shown to encode a functional protein able to transactivate the BLV long terminal repeat-directed gene expression in the infected cells. The encountered level of transactivation was about one third of that measured in BLV-infected fetal lamb kidney cell lysates.

Animals↗

PubMed1987

The hemagglutinin-neuraminidase (HN) gene of Newcastle disease virus strain Italien (ndv Italien): comparison with HNs of other strains and expression by a vaccinia recombinant.

A cDNA library was constructed with poly(A+) mRNA from cells infected with the virulent Italien NDV strain. A clone that hybridized to the HN gene mRNA was sequenced. A long open reading-frame encodes for a protein of 571 amino acids, with a calculated molecular weight of 61,900, including 13 cysteine residues and six potential glycosylation sites. To define the sequence changes that occurred in the avian paramyxovirus hemagglutinin-neuraminidase (HN) during the evolution of virulence, we have studied the HNs of the virulent Italien NDV strain, the mesovirulent Beaudette strain and the nonvirulent Hitchner strain. The majority of amino acid variations are conservative changes but they cluster at 4 preferential sites in the putative head of HN. The clusters of amino acid substitutions are intimately associated or overlap with regions of HN rich in charged amino acid residues and in cysteines. The latter are conserved not only between HNs from all 3 NDV strains but also between HNs of 4 different paramyxoviruses, NDV, SV 5, Sendai and PI 3. The HN coding sequence was inserted into the genome of vaccinia virus under the control of vaccinia P 7.5 K transcriptional regulatory sequences. Expression of native HN proteins at the surface of recombinant HN vaccinia-infected cells was demonstrated by indirect immunofluorescence with 2 anti-HN monoclonals.

Amino Acid Sequence↗

PubMed1987

Expression at the cell surface of native fusion protein of the Newcastle disease virus (NDV) strain Italien from cloned cDNA.

A cDNA library was constructed with poly(A)+-mRNAs from NDV-Italien infected BHK-21 cells. A clone, that hybridized to the F gene mRNA, was sequenced. A long open reading frame encodes for a protein of 553 amino acids, with a calculated molecular weight of 59,153, consisting of twelve cysteine residues and six potential glycosylation sites. The protein sequence contains a hydrophobic region at the N-terminus of F1 and a presumptive long transmembrane fragment near the C-terminus. Comparison of the F proteins from NDV strains Italien and Australia-Victoria shows that the sequences are very similar, with conservation of most cysteine residues and of the potential glycosylation sites. The F coding sequence was inserted into the genome of vaccinia virus under the control of vaccinia P7.5 transcriptional regulatory sequences. Expression of F protein was demonstrated by indirect immunofluorescence with five anti-F monoclonal antibodies known to react with conformational epitopes.

Amino Acid Sequence↗