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Biomedical subjects

D Archambault

Publications and source records attributed to D Archambault.

At least 37 records · Page 2Linked to original sources
PubMed1996

Kinetics of humoral immune response to the major structural proteins of the porcine reproductive and respiratory syndrome virus.

The kinetics of appearance of antibodies directed to the major structural proteins N, M and E of porcine reproductive and respiratory syndrome virus (PRRSV) was followed in pigs naturally- and experimentally-exposed to the virus. Specific IgM antibody titers were first detected by indirect immunofluorescence (IIF) at the end of the first week of PRRSV infection, peaked by day 14 to 21 post-inoculation (p.i.), then rapidly decreased to undetectable levels by day 35 to 42 p.i. On the other hand, specific IgG antibody titers peaked by day 21 to 28 p.i. and remained unchanged to the end of the 6- or 9-week observation period; in addition, a persistent viremia was observed. Virus neutralizing (VN) antibody titers > 8 were not detected until 3 to 4 weeks p.i. Taken together, the results obtained by Western blotting analyses using purified virus and E. coli-expressed ORFs 5 to 7 gene products, suggested that antibodies directed against the envelope E protein appear by day 7 p.i., whereas antibodies directed against the nucleocapsid N and membrane M proteins can only be detected by the end of the second week p.i. No correlation could be demonstrated between VN and IIF antibody titers, viremia, and viral protein specificities of circulating antibodies at various times p.i.

Animals↗
PubMed1996

Antibody production and blastogenic response in pigs experimentally infected with porcine reproductive and respiratory syndrome virus.

Seven five-week piglets were infected intranasally with 10(5) TCID50 of porcine reproductive and respiratory syndrome (PRRS) virus strain IAF.exp91. All virus-exposed pigs developed fever, labored abdominal breathing, conjunctivitis, and lymph node enlargement within the first 96 h postexposure (PE), which continued to d 10 to 14 PE. Two pigs that were necropsied at d 7 and 10 PE had diffuse interstitial pneumonitis, cardiopathy and lymphadenopathy. All 5 remaining pigs produced serum IgM and IgG antibodies against PRRS virus by 7 or 14 days PE, as demonstrated by indirect immunofluorescence. This corresponded with the capability of isolating the virus from serum d 7 to d 49 or d 63 PE. Low serum neutralizing antibody titers were detected in 3 of the virus-exposed pigs by 35 days PE. A transient episode of diminished proliferative response of peripheral blood lymphocytes to mitogens phytohemagglutinin (PHA) and concanavalin A (Con A) was observed in the virus-exposed pigs at d 3 PE. However, in vitro spontaneous uptake of [3H]-thymidine was significantly increased in lymphocyte cultures of the same pigs at d 7 or d 14 PE. These results suggest polyclonal activation of peripheral blood lymphocytes.

Animals↗
PubMed1995

Cloning of porcine cytokine-specific cDNAs and detection of porcine tumor necrosis factor alpha, interleukin 6 (IL-6), and IL-1 beta gene expression by reverse transcription PCR and chemiluminescence hybridization.

A reverse transcription PCR assay with porcine cytokine-specific primers was developed to clone cDNA fragments and generate cDNA probes that were specific for porcine tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and IL-1 beta. The specificities of the cDNA PCR products were confirmed by sequence analysis on the basis of known porcine cytokine gene sequences. The reverse transcription PCR assay was also used to study cytokine mRNA expression in lipopolysaccharide (LPS)-stimulated and control unstimulated porcine alveolar macrophages. The cDNA products were analyzed in ethidium bromide-stained agarose gels, and the transcription level of each cytokine was determined relative to the endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) RNA level of each cytokine by measuring the intensity of the chemiluminescence hybridization signals by densitometric scanning. Various levels of cytokine mRNAs were detected in both LPS-stimulated and control unstimulated cells. Thus, TNF-alpha mRNA levels were enhanced in the cell cultures stimulated for 6 h with LPS compared with those in control cell cultures. No differences in TNF-alpha transcription levels between LPS-stimulated and control cells were observed after incubation for 24 or 55 h. Enhancements of IL-6 and IL-1 beta mRNA levels were also observed in the cultures stimulated with LPS for 6 and 24 h compared with the cytokine mRNA levels in control cell cultures. The presence of cytokine mRNA transcripts in the LPS-stimulated macrophage cultures correlated with the detection of these soluble cytokines by the bioassays. In contrast, no soluble cytokine was detected in control macrophage culture supernatants in the presence of cytokine mRNA transcripts.

Animals↗
PubMed1994

Phosphorothioate oligonucleotides inhibit the replication of lentiviruses and type D retroviruses, but not that of type C retroviruses.

Phosphorothioate analogs of oligodeoxynucleotides at a concentration of 2 microM protected Himalayan tahr cells from infection by caprine arthritis encephalitis virus (CAEV) and equine dermis cells from infection by equine infectious anemia virus (EIAV). The characteristics of this inhibition against these lentiviruses are similar to those previously described for the inhibition of HIV-1 in ATH8 cells [17]. Thus, the 28-mer homo-oligomer of cytidine [S-(dC)28] was at least as effective as three anti-sense sequences targeted to the LTR, gag, and env regions of CAEV. The effectiveness of homo-oligomers of equal length was in the order C >> A > T, and a random 28-copolymer with a composition of 2C:1G was as effective as S-(dC)28. Shorter oligonucleotides were less effective (28 > 14 > 5 mers) for all base compositions tested. While replication of a simian type D retrovirus was inhibited by S-(dC)28, this compound did not inhibit the cytopathogenicity of two type C retroviruses, amphotropic murine leukemia virus (MuLV), and baboon endogenous virus, when they were tested in the same cell lines used to support the replication of lentiviruses. Southern blot analysis of the high molecular weight DNA of drug-treated CAEV-infected cells showed that S-(dC)28 was acting at or before the reverse transcription step. Our present data and the earlier finding that S-(dC)28 is a potent in vitro inhibitor of the MuLV reverse transcriptase [15] suggest that S-(dC)28 is acting very early in the replication cycle of these lentiviruses. Since MuLV reverse transcriptase is inhibited in vitro, but its replication is not blocked in permissive cells, our data suggest that the phosphorothioate oligonucleotides are preventing virus attachment.

Animals↗
PubMed1994

Detection of equine arteritis virus following amplification of structural and nonstructural viral genes by reverse transcription-PCR.

A reverse transcription (RT)-PCR assay was developed for the detection of equine arteritis virus (EAV) in cell culture supernatant and in horse semen. Four different sets of oligonucleotide primers complementary to sequences located in the 3' end of the polymerase gene (open reading frame [ORF] 1b) and to sequences representing the entire ORFs 3, 4, and 7, which encode for nonstructural (ORFs 3 and 4) or viral nucleocapsid (ORF 7) proteins, were compared for their abilities to amplify the targeted EAV sequences by the RT-PCR procedure. The sensitivities of the RT-PCR for amplification of EAV sequences located in the 3' end of ORF 1b and ORF 4 were 2 median tissue culture infective doses (TCID50s) of viral particles in the EAV-infected cell culture supernatant for both ORFs and 20 and 200 TCID50s of viral particles, respectively, in virus-containing horse semen. The sensitivities were much lower when primers complementary to ORFs 3 and 7 were used in the RT-PCR, with a minimum detection limit of only 2 x 10(4) TCID50s of viral particles in virally infected cell culture supernatant, as determined by analyzing the resulting RT-PCR products on ethidium bromide-stained agarose gels. The specificities of the RT-PCR assays for all primer sets tested were confirmed when the amplified cDNA products of the expected size reacted positively with the corresponding virus-specific digoxigenin-labeled cDNA probes in the chemiluminescence assays. Although the sensitivity of the RT-PCR for amplification of ORF 3 and 7 sequences was lower, all sets or primers were capable of amplifying several cell culture-adapted EAV field isolates when the virus was present in high enough quanities in the test sample. When horse semen samples were analyzed for the presence of EAV by the RT-PCR with primers specific to the ORF 1b 3' end and ORF 4 sequences and by virus isolation in cell cultures, there was 100% concordance among the assays. The RT-PCR assay targeting the 3' end of ORF 1b and/or ORF 4 EAV RNA may be an alternative to conventional methods for the diagnosis of EAV infection in horses.

Animals↗
PubMed1994

Influences of renal nerves and pregnancy on renin secretion in sheep.

To investigate the role of the renal nerves in the control of renin secretion during pregnancy, we prepared sheep with one denervated kidney, bilateral renal vein catheters, and an inflatable aortic occluder. The renin secretory responses to step reductions of renal perfusion pressure (RPP) of the innervated and denervated kidneys were compared in eight nonpregnant and nine pregnant (115-130 days gestation) sheep in a normal conscious state. Nonpregnant sheep had average basal levels of mean arterial pressure (MAP) of 91 +/- 3 mmHg, plasma renin activities (PRA) of 2.3 +/- 0.4 ng ANG I.ml-1.3 h-1, and plasma angiotensin (ANG) concentrations of 8.4 +/- 1.1 pg/ml. Pregnant sheep had reduced levels (P < 0.01) of MAP (76 +/- 3 mmHg) but elevated levels of PRA (3.8 +/- 0.4 ng ANG I.ml-1.h 3-1; P < 0.5) and ANG II (12.0 +/- 1.6 pg/ml; P = 0.08). Four successively reduced levels of RPP were observed for 15 min each in both groups of sheep. In both groups, RPP was reduced to a final level of 51 +/- 2 mmHg. The renal venous-arterial difference of PRA (v-aPRA) from the innervated kidneys was increased as RPP was reduced. However, there was little response of v-aPRA to RPP in denervated kidneys. In nonpregnant sheep, the relationship between RPP and renin secretion rate was characterized by an initially slow phase, over which small reductions of RPP resulted in small increases in renin secretion. As RPP fell, this relationship became progressively steeper in nonpregnant ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1994

Persistence of porcine reproductive and respiratory syndrome virus infection in a swine operation.

A herd of Quebec seedstock pigs experienced in early 1992 a typical outbreak of porcine reproductive and respiratory syndrome (PRRS) associated with lesions of interstitial, proliferative and necrotizing pneumonia in weaned piglets. The nature of the infection was confirmed by serology using indirect immunofluorescence (IIF) and virus isolation in primary cultures of porcine alveolar macrophages (PAM). Farm production recovered after eight weeks of losses. In order to evaluate the persistence of infection in the herd, five SPF-piglets were introduced in two different sections of the PRRS-affected barn four months after the disappearance of clinical symptoms, and two others were placed in a neighboring building with apparently healthy farrow-to-finnish pigs. Clinical signs, body temperature, humoral immune response, virological and histopathological findings were recorded over a 42-day period. Clinical signs were evident in all of the sentinels and prolonged fever (> or = 40 degrees C) was recorded one day post-exposure (PE). Antibody titers to PRRS virus could be detected by IIF on PAM seven days PE, and reached 1:1024 by day 21 PE. Three of the sentinels developed significant virus neutralizing antibody titers (> 1:8 to < or = 1:128) by day 35 PE. In all cases, the virus could be isolated from the serum between day 7 and 42 PE. Thus, the virus and specific antibodies coexisted for several weeks. Lesions of interstitial pneumonia was demonstrated in few animals. In experimental inoculation studies, the viral strain isolated from the sentinel pigs produced severe reproductive disorders in two sows inoculated at 95 days of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[The bovine immunodeficiency virus: 1990-1992 update].

Substantial progress has been shown on the bovine immunodeficiency-like virus (BIV) in 1990-1991 and up to mid-1992. The genomic sequences of BIV were analysed in detail and several subgenomic RNAs were identified. Nucleic acid molecular probes, PCR (polymerase chain reaction) amplification and a novel Western blotting procedure have been of great assistance for the experimental diagnosis of BIV. Antibody response after BIV infection has shown that antibodies to p26 antigen were always present in naturally and experimentally infected animals. The experimental infection of sheep, goats and rabbits was confirmed. BIV causes an infection with no pathognomonic clinical signs in cattle and sheep for at least 3 and 4 years, respectively. Finally, there is not yet any evidence of BIV immune response disturbances similar to that of human AIDS.

Animals↗
PubMed1992

Defective viral particles in caprine arthritis encephalitis virus infection.

Attempts to isolate full-length unintegrated circular forms of the caprine arthritis encephalitis virus (CAEV) genome yielded only a large number of molecules with deletions. The 3' borders of most of these deletions were near the U3 region of the long terminal repeat whereas the 5' edges were found at various upstream sites within pol or env. With one exception, gag sequences were always present. Analysis of molecular clones derived from integrated proviral CAEV genomes from the same infected cells showed a similar spectrum of deletions. The presence of transcriptionally active elements within the U3 domain of the defective genomes, as well as cis-acting elements within the leader sequences known to be required for efficient encapsidation of viral RNA, suggested that the defective viral DNA genomes could be transcribed into defective RNA molecules which could then be packaged into virions. Isopycnic density gradient centrifugation of supernatants of infected cell cultures indicated the presence of particles with densities less than that expected for intact virions (1.16 g/cc). Northern analysis revealed the presence of smaller viral-specific RNAs that lacked env sequences. These data, along with the structures of the molecular clones, suggest that CAEV stocks contain particles with defective genomes. The role of these particles in influencing the course of virus infection remains to be determined.

Animals↗
PubMed1991

Characterization and comparative bactericidal activity of monoclonal antibodies to Bordetella pertussis lipo-oligosaccharide A.

Spleen cells from mice immunized with a Bordetella pertussis N-lauroyl sarcosine membrane extract (SME) were used to generate hybridoma cells lines producing monoclonal antibodies (mAbs). Seven mAbs were shown to be specific to B. pertussis lipo-oligosaccharide (LOS) by immunoblotting of SME or purified LOS following SDS-PAGE. All mAbs reacted with the B. pertussis Tohama I strain of the LOS AB phenotype, and did not react with the atypical variant strain 134 of the LOS B phenotype. The immune reactivity of the mAbs was retained after treatment of SME with proteinase K and was lost after sodium periodate treatment. No cross-reactivity was observed with the mAbs when tested against B. parapertussis and other Gram-negative bacteria. However, all mAbs reacted with B. bronchiseptica. Binding assays with live B. pertussis cells demonstrated that mAbs strongly reacted with cell surface exposed antigenic determinants. High bacterial cell lytic capability was observed for five of these mAbs. Concentrations between 0.22 and 2.2 micrograms mAb ml-1 (0.1 and 1 microgram per 450 microliter assay) purified by protein A were required to kill at least 50% of the bacteria. Competition immunoassays with biotinylated antibodies showed that the bacteriolytic and non-bacteriolytic mAbs were directed to different epitopes of the B. pertussis LOS A.

Animals↗
PubMed1990

Articulatory impairment associated with tardive dyskinesia.

The speech of two patients with tardive dyskinesia was studied, and one neuroleptic-treated patient having no signs of overt tardive dyskinesia served as control. A structured interview, including reading, repetition of sentences, and spontaneous conversation, was performed. A phonetic transcription and analysis of abnormal phonemes was done by a linguist under blind conditions. Both patients with tardive dyskinesia had abnormal phonemes whereas the control patient had none. These differences could not be explained by age, direct neuroleptic effect, or neuroleptic exposure time. The abnormal phonemes were all consonants. The authors conclude that tardive dyskinesia may cause articulatory communication problems.

Adult↗
PubMed1990

Study of virus excretion in feces of diarrheic and asymptomatic calves infected with rotavirus.

Infection of calves by rotavirus could lead to diarrhea or subclinical disease. Therein, kinetic of viral excretion from a group of asymptomatic calves, previously exposed to a virulent strain of rotavirus, is compared to that of a group the calves of which had diarrhea associated with rotavirus infection. As determined by an enzyme-linked immunosorbent assay (ELISA), duration of rotavirus shedding in feces and maximum yield of virus antigen were similar within the two groups of calves. Rotaviruses isolated from the two above groups of animals were antigenically related as shown by neutralization tests, and showed a similar RNA electrophoretic profile. In conclusion, it is likely that both asymptomatic and diarrheic calves infected by rotavirus are equally a major source of contamination to contact healthy calves.

Animals↗
PubMed1990

Equine infectious anemia virus derived from a molecular clone persistently infects horses.

A full-length molecular clone of equine infectious anemia virus (EIAV) was isolated from a persistently infected canine fetal thymus cell line (Cf2Th). Upon transfection of equine dermis cells, the clone, designated CL22, yielded infectious EIAV particles (CL22-V) that replicated in vitro in both Cf2Th cells and an equine dermis cell strain. Horses infected with CL22-V developed an antibody response to viral proteins and possessed viral DNA in peripheral blood mononuclear cells, as determined by polymerase chain reaction assays. In addition, horses infected with CL22-V became persistently infected and were capable of transmitting the infection by transfer of whole blood to uninfected horses. However, CL22-V, like the parental canine cell-adapted virus, did not cause clinical signs in infected horses. Reverse transcriptase assays of CL22-V- and virulent EIAV-infected equine mononuclear cell cultures indicated that the lack of virulence of CL22-V was not due to an inability to infect and replicate in equine mononuclear cells in vitro.

Animals↗
PubMed1990

[Bovine immunodeficiency virus: short review].

A bovine visna-like virus was isolated by Van Der Maaten et al (1972) but it did not draw attention since, at that time, most efforts were directed towards research on bovine leukemia virus. However, new interest was shown on the bovine visna-like virus after the isolation of the human immunodeficiency virus (HIV), because of the urgent need for developing animal models for the acquired immunodeficiency syndrome (AIDS). The purpose of this paper is to describe the different stages of the identification of the bovine virus and to up-date knowledge about it. The bovine visna-like virus has recently been named the bovine immuno-deficiency-like virus (BIV) and is the sole bovine lentivirus known to-date. BIV shares morphologic, antigenic and genomic characteristics with other lentiviruses. It grows and induces large syncytia in vitro and generates virus-productive and latent infections in cell culture. It causes persistent infection and slow progressive disease in cattle and probably in sheep. As target cells of the virus are leukocytes, the type of which is unknown, perturbations of the immune system are expected. Consequently, BIV may potentiate the occurrence of secondary infections and play a role in retroviral, multiple infections. It is not oncogenic. Transmission appears to occur in cattle by contact, but evidence of transmission in human beings has not been shown. Finally, BIV may be a potential model in vitro and in vivo for HIV and AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Development of an enzyme-linked immunosorbent assay for equine infectious anemia virus detection using recombinant Pr55gag.

To provide more sensitive and convenient methods for the detection of equine infectious anemia virus (EIAV), we developed an enzyme-linked immunosorbent assay (ELISA) employing the EIAV gag precursor (Pr55gag) produced by using recombinant DNA techniques. The antigenic reactivity of the recombinant EIAV Pr55gag was found to be equivalent to that of the virion p24gag and elicited high-titered antiserum in rabbits. When a large number of horse sera were analyzed for the presence of antibodies to EIAV by this ELISA, a radioimmunoassay for EIAV p15gag, or the standard agar gel immunodiffusion test, there was 98.7% concordance among the assays. By using the ELISA it was possible to specifically detect antibodies earlier after experimental infection of horses with EIAV than with the other two tests. A competition ELISA developed in order to detect EIAV gag antigens was found to be approximately 15 times more sensitive than the radioimmunoassay for EIAV p15gag. Antigens of other animal lentiviruses as well as those of the prototype oncovirus failed to compete in this assay.

Animals↗
PubMed1989

Effect of sodium diethyldithiocarbamate, Corynebacterium parvum and mycobacterium cell wall extract on in vitro blastogenic responses of bovine blood lymphocytes.

In vivo inoculation of three-month-old calves with sodium diethyldithiocarbamate (DTC), killed Corynebacterium parvum or mycobacterium cell wall extract (MCWE) resulted in an enhancement of in vitro peripheral blood lymphocyte blastogenic responses to mitogens phytohemagglutinin (PHA) and Concanavalin A (Con A) in the first three days after treatment. In a separate experiment, blood lymphocytes isolated from a healthy nontreated calf were incubated in vitro in presence of each of the same immunostimulating agents and tested for their blastogenic responses to PHA and Con A. The results showed that all immunostimulants, excepting DTC, enhanced the in vitro blastogenic responses of lymphocytes to PHA and Con A. Finally, addition of MCWE to cultures of blood lymphocytes isolated from calves vaccinated intramuscularly with bovine rotavirus and adjuvant resulted in an enhancement of the in vitro lymphocyte transformation to rotavirus. Our study demonstrated that DTC, killed Corynebacterium parvum and mycobacterium cell wall extract were able to enhance bovine T cell proliferation in vitro.

Adjuvants, Immunologic↗
PubMed1988

Standardization and kinetics of in vitro bovine blood lymphocyte stimulation with bovine rotavirus.

Two groups of 3-month old calves were immunized intramuscularly with attenuated bovine rotavirus and boosted 21 and 42 days later. The first group of three calves were vaccinated with live virus emulsified with incomplete Freund's adjuvant (IFA) and the second group was immunized with live virus suspended in phosphate buffered saline (PBS). Three other calves, serving as controls, were inoculated with PBS emulsified with IFA. The specific cell-mediated and antibody responses of the animals were studied. Preliminary analysis of in vitro peripheral blood lymphocyte transformation to bovine rotavirus determined optimal conditions as: 96 h culture period, 5 X 10(5) cells per culture in RPMI 1640 medium containing 10% heat-inactivated bovine fetal serum and the use of inactivated virus in the cell culture at a concentration of 5 X 10(6) median tissue culture infective dose before inactivation. Specific blastic stimulation was observed on calves immunized with the rotavirus emulsified with IFA after the second and third vaccine inoculation with stimulation index values varying from 2.00 to 5.73. Serum neutralizing antibody titers of 1/25,600 were also induced in the same calves. Calves immunized with rotavirus-PBS suspension developed a mean antibody titer of 1/1,600, but showed no specific lymphocyte stimulation. No increase in specific immune responses was detected in the control animals.

Animals↗