PubMed Health⌕ Search

Biomedical subjects

P G Balboni

Publications and source records attributed to P G Balboni.

At least 19 recordsLinked to original sources
PubMed2001

Mice genetic immunization with plasmid DNA encoding a secreted form of HSV-1 gB induces a protective immune response against herpes simplex virus type 1 infection.

Intramuscularly (i.m.) delivered plasmid DNA encoding a secreted form of glycoprotein B of herpes simplex virus type 1 (HSV-1 gB1s) was evaluated for the ability to elicit a protective immune response in Balb/c mice. Animals received three i.m. injections of a gB1s expression plasmid (pRP-RSV-gB1s) or of a wild-type transmembrane gB1 coding plasmid (pRP-RSV-gB1), while control mice were injected with the vector alone (pRP-RSV). A specific antibody response was observed in almost all immunized animals, and in most cases antibodies were also detected after 1 month in the absence of further vaccine boosts. Serum antibodies mostly displayed neutralizing activity against HSV-1. Glycoprotein B1s DNA immunization was also effective in protecting animals against the primary infection induced by a subsequent HSV-1 challenge and limited HSV-1 infection of sensitive ganglia.

Animals↗
PubMed2000

Local and systemic inoculation of DNA or protein gB1s-based vaccines induce a protective immunity against rabbit ocular HSV-1 infection.

A secreted form of gB1 (gB1s), previously shown to protect rabbits against HSV-1 ocular infection when inoculated systemically, was delivered to rabbit periocular area to evaluate its vaccine efficacy upon local administration. The efficacy of local or systemic inoculation of a gB1s-DNA-based vaccine in the rabbit model of ocular HSV-1 infection was assessed in parallel flow. Rabbits received four inoculations of the different immunogens, then immune responses and clinical symptoms were evaluated. Both the local protein and the systemic DNA administration elicited a neutralizing antibody response, reduced ocular symptoms with respect to controls (P<0.01), and completely prevented the death of rabbits from encephalitis. Conversely, local DNA vaccination did not induce any detectable antibody response, and could only partially protect rabbits from the development of encephalitis and severe ocular infection.

Animals↗
PubMed1999

DNA immunization with HIV-1 tat mutated in the trans activation domain induces humoral and cellular immune responses against wild-type Tat.

Intramuscular immunization of mice with plasmids encoding two transdominant negative mutants of the HIV-1 Tat protein (Tat22 and Tat22/37) elicited a humoral response to wild-type Tat that is comparable to that induced by inoculation of wild-type tat DNA or Tat protein. The percentage of the responders and the Ab titers continued to increase after three additional DNA boosts and pretreatment with bupivacaine at the site of inoculation, without a significant difference (p > 0.05) among the three groups of mice immunized with mutant and wild-type tat genes. By utilizing synthetic peptides representing the amino acid sequence of Tat, one major B cell epitope was defined within the cysteine-rich domain of Tat. Anti-Tat IgG Abs directed against this epitope were found in mice immunized with all tat DNA constructs, whereas different Tat epitopes were detected in mice immunized with the Tat protein. Similarly, IgG2a was the predominant isotype in DNA-immunized mice, with both mutants and wild-type tat genes, as compared with protein immunization, which induced mostly IgG1 and IgG3. Sera from most immunized mice neutralized the effect of extracellular Tat in activating HIV-1 replication. A cellular response was also elicited as indicated by the proliferation of splenocytes when stimulated with wild-type Tat. These results indicate that the wild-type Tat Ag is recognized by Abs and T cells induced by DNA immunization with mutated tat genes, suggesting the possible use of these Tat transdominant mutants, lacking viral trans activation activity and capable of blocking wild-type Tat activity, in the development of an anti-HIV-1 vaccine.

3T3 Cells↗
PubMed1997

Studies on the effect of the combined expression of anti-tat and anti-rev genes on HIV-1 replication.

A series of retroviral vectors with potential anti-tat and antirev activity was developed. Vectors containing a tat transdominant negative mutant (tat22/37) and an RRE decoy in different positions, directed by the same promoter or by different promoters, were generated. Retroviral vectors containing tat22/37 and the RevM10 transdominant negative mutant were also constructed. Jurkat cells were transduced with the recombinant retroviruses to produce monoclonal and polyclonal cultures. In these cell lines the recombinant proviruses were correctly integrated and expression of the inserted genes was detected by Northern blot or RT-PCR analysis. However, infection of these cell lines with HIV-1 showed that none of these recombinant constructs inhibited virus replication at a high multiplicity of infection (MOI). At a low MOI, two cell clones containing tat22/37 and the RRE decoy in 3' position showed a long lasting protection against virus replication, in comparison to control cultures expressing tat22/37 or RRE alone. Combination of tat and rev mutants was ineffective in inhibiting HIV-1 replication at both low and high MOIs. At a low MOI, HIV-1 replication was efficiently blocked in two cell clones expressing the RevM10 mutant alone. These results show a synergic effect of anti-tat and anti-rev molecules when the RRE sequence is cloned 3' to tat22/37, suggesting the possibility of using this vector design to control HIV-1 replication.

DNA, Recombinant↗
PubMed1997

Inhibition of HIV-1 replication by a Tat transdominant negative mutant in human peripheral blood lymphocytes from healthy donors and HIV-1-infected patients.

It was previously shown that a tat mutant (tat22) where cysteine 22 is substituted by glycine behaves as a transdominant negative mutant in Jurkat T cells lytically or latently infected by HIV-1. In this study we demonstrate that tat22 controls HIV-1 replication in primary cells. This effect was observed both after in vitro infection of peripheral blood mononuclear cells (PBMCs) from normal donors and after reactivation of the latent infection in PBMCs from seropositive patients. The antiviral effect of tat22 was limited to conditions of low virus production. The use of tat22 may be promising for a gene therapy approach to AIDS during the asymptomatic phase of the disease allowing control of virus replication in infected cells and inhibition of virus spread to uninfected cells.

Gene Products, tat↗
PubMed1996

Inhibition of HIV-1 replication and reactivation from latency by tat transdominant negative mutants in the cysteine rich region.

Tat mutants (tat22, tat37 and tat22/37) were constructed in the transactivation domain, where cysteines at positions 22 or/and 37 were substituted with glycine and serine, respectively. These mutants were expressed either in a BK virus episomal vector or in the retroviral vector LXSN. Constitutive production of tat22 by Jurkat T cells in the context of both vectors blocked HIV-1 replication during lytic infection. Conversely, the tat37 mutant did not show any inhibitory activity and tat22/37 displayed a mild effect on HIV-1 infection only when expressed by the recombinant retrovirus. However, constitutive production of tat22/37 by the BK virus vector in Jurkat T cells chronically infected by HIV-1 was effective in blocking reactivation of viral replication induced by tumor necrosis factor-alpha or human herpesvirus-6. These results suggest that mutants in the transactivation domain of tat may be considered in designing alternative strategies to control HIV-1 replication and reactivation from latency during different phases of infection.

Base Sequence↗
PubMed1996

[Experimental study of postoperative lavage: standardization of the method].

Postoperative infections are an outstanding problem in a surgical department. We have been studying them from a clinical and experimental point of view has a long time. In this study we present a method standardisation of postoperative peritoneal lavage as prevention of surgical infections. Winstar mice, infected with intra peritoneal E. coli cultures, underwent peritoneal lavage with saline solution or sterile water. The results showed the right amount of solution and the exact administration of lavage according to grade of infection. Encouraged by this result we are going to test the efficacy of anti microbial agents for the postoperative peritoneal lavage.

Animals↗
PubMed1993

Inhibition of human immunodeficiency virus reactivation from latency by a tat transdominant negative mutant.

A BK virus (BKV) expression vector, specific for human cells, was engineered to express antisense human immunodeficiency virus type 1 (HIV-1) tat cDNA (tat-AS) or a tat mutant in cysteine 22 (tat22). Cysteine residues in the cysteine-rich domain of tat are necessary for tat transactivation of the HIV-1 long terminal repeat (LTR). Both the AS tat and the tat mutant significantly inhibited transactivation by tat when assayed in cells cotransfected with an expression vector where the reporter gene for chloramphenicol acetyl transferase was driven by the HIV-1 LTR. Infection of Jurkat cell clones stably expressing tat22 (Jurkat/tat22) or tat-AS (Jurkat/tat-AS) with HIV-1 did not show differences in virus titer in comparison to HIV-1-infected control cells. However, in two Jurkat/tat22 cell clones, entrance of HIV-1 into latency was accelerated significantly and reactivation of HIV-1 from latency induced by tumor necrosis factor-alpha (TNF-alpha) or tat was blocked. These results suggest that, in a combined and integrated approach to the treatment of acquired immunodeficiency syndrome (AIDS), anti-tat genetic therapy could be successfully applied to maintain virus in latency, thereby extending the duration of the asymptomatic phase preceding full-blown AIDS.

BK Virus↗
PubMed1991

High expression of exogenous cDNAs directed by HIV-1 long terminal repeat in human cells constitutively producing HIV-1 tat and adenovirus E1A/E1B.

A eukaryotic vector-host cell system is described where the additive transactivating effects of HIV-1 tat and adenovirus E1A on HIV-1 long terminal repeat (LTR) are exploited to increase expression of exogenous cDNAs. Human 143B and 293 cells, the latter constitutively producing E1A, were used as host cell lines. The bacterial gene chloramphenicol acetyltransferase (CAT) and the hepatitis B surface antigen (HBs-Ag) gene were employed as reporter genes inserted in pRPneoU3R, an episomal vector containing BK virus replication origin and early region, where cDNAs are expressed under control of HIV-1 LTR. The 293 cells were transformed by tat expression vectors to constitutively express tat. Stable cell clones of 293tat cells, constitutively expressing CAT after transformation with pRPneoU3R-CAT, show a CAT activity 600-fold higher than normal 293 transformed cells. CAT expression obtained in normal 293 cells can be transiently increased 10-fold by transfection by vectors expressing tat. The 293tat cells transformed by pRPneoU3R-HBs, an episomal vector expressing HBs-Ag from HIV LTR, yielded stable cell clones secreting HBs-Ag in the culture medium at a concentration up to 744 ng/ml or 44 ng/10(6) cells/24 h, 48-fold more than normal 293 cells. The use of this system for constitutive or inducible expression of sequences under control of HIV-1 LTR is discussed in view of possible applications for diagnostic, vaccinal and therapeutic purposes.

Adenovirus Early Proteins↗
PubMed1990

Experimental keratitis in rabbits by human HSV-1 variants: prevention and treatment.

The efficacy of different therapies and vaccine preparations was assessed for treating or preventing herpetic ocular keratitis induced by experimental inoculation in rabbits with two HSV-1 variants that display different pathogenetic potential. Early administration of acyclovir (ACV) promoted fast healing and prevented neurologic involvements: alpha-interferon (alpha-IFN) was less efficient than ACV; combined therapy with both drugs increased the antiviral effects. In an attempt to prevent the disease, rabbits were vaccinated with a slightly pathogenic HSV-1 variant or with a secreted form of an engineered HSV-1 glycoprotein gB (gB-1s) and were subsequently challenged with a highly pathogenic HSV-1 variant. Immunization of rabbits with gB-1s was much more efficient than immunization with live virus in reducing the severity of herpetic keratitis and in preventing CNS disease.

Acyclovir↗
PubMed1990

Protection from herpes simplex virus type 1 lethal and latent infections by secreted recombinant glycoprotein B constitutively expressed in human cells with a BK virus episomal vector.

The herpes simplex virus type 1 (HSV-1) glycoprotein B (gB-1) gene, deleted of 639 nucleotides that encode the transmembrane anchor sequence and reconstructed with the extramembrane and intracytoplasmic domains, was cloned under control of the Rous sarcoma virus long terminal repeat in the episomal replicating vector pRP-RSV, which contains the origin of replication and early region of the human papovavirus BK as well as a cDNA for a mutant mouse dihydrofolate reductase that is resistant to methotrexate. gB-1 (0.15 to 0.25 pg per cell per 24 h) was constitutively secreted into the culture medium of pRP-RSV-gBs-transformed human 293 cells. Treatment of transformed cells with methotrexate at high concentrations (0.6 to 6 microM) increased gB-1 production 10- to 100-fold, because of an amplification of the episomal recombinant. Mice immunized with secreted gB-1 produced HSV-1- and HSV-2-neutralizing antibodies and were protected against HSV-1 lethal, latent, and recurrent infections. Constitutive expression of secreted gB-1 in human cells may establish a system to develop diagnostic material and a subunit vaccine for HSV infections.

Animals↗
PubMed1988

New BK virus episomal vector for complementary DNA expression in human cells.

The properties of pRP-c, a new vector for complementary DNA (cDNA) expression, are described. The vector contains the early region and replication origin of BK virus (BKV), a human papovavirus. Due to the presence of these BKV sequences, pRP-c replicates in human cells allowing amplification of inserted cDNAs. The promoter, intron and polyadenylation region for cDNA expression are separated by unique restriction sites and can therefore be individually excised and substituted with different transcription signals. Coding sequences of the bacterial genes for chloramphenicol-acetyl transferase (CAT) or neomycin phosphotransferase (neo) were inserted into the cDNA cloning site of pRP-c and expressed in human cells in transient assays or stable clones. In both cases expression of the inserted sequences was significantly more efficient than by using the integration vectors pSV2CAT and pSV2neo, demonstrating the advantages of episomal expression vectors in human cells. Possible uses of pRP-c to express viral and cellular cDNAs in human cells are discussed.

BK Virus↗
PubMed1988

Factors affecting amplification of BK virus episomal vectors in human cells. Brief report.

Analysis of factors determining replication of BK virus (BKV) episomal vectors in human cells showed that vector copy number was related to the level of BKV T antigen expression. T antigen was synthesized efficiently, as assessed by indirect immunofluorescence, in vector-transfected primary embryonic fibroblasts undergoing neoplastic transformation. Surprisingly, transfected continuous cell lines (143 B, HeLa and KB), kept under biochemical selection or tested in transient assays, produced negligible amounts or no T antigen, revealed only by a sensitive ELISA test, suggesting that in these cells vector amplification was under the control of cellular factors. Presence or absence of BKV late region sequences, BKV strain, orientation of the inserted genes and presence or absence of selection were not relevant for vector replication. Type of biochemical selection, however, was important, since BKV vectors containing the thymidine kinase gene replicated better than those containing the neo gene. Despite great variability, vector copy number increased in transfected clones of adenovirus 5-transformed 293 cells, in the absence of immunofluorescence detectable T antigen. These cells express adenovirus immediate early proteins E1A and E1B which may directly or indirectly activate BKV origin of replication.

Antigens, Polyomavirus Transforming↗
PubMed1988

Dead fecal yeasts and chronic diarrhea.

The authors report 20 patients in whom a large number of dead or severely damaged yeast cells, supposedly Candida albicans yeasts, were the possible cause of chronic recurrent diarrhea and abdominal cramps. It is suggested that the presence of large numbers of these microorganisms in stools may be considered among the possible etiologies of diarrhea in the 'irritable bowel syndrome'. The possible source of these yeast-like cells, the causes of cell damage, and the mechanisms by which these organisms may induce diarrhea should be investigated.

Adult↗