Biomedical subjects

Partha Bhattacharjee

Publications and source records attributed to Partha Bhattacharjee.

3 recordsLinked to original sources

PubMedDate not supplied

Ocular reactivation phenotype of HSV-1 strain F(MP)E, a corticosteroid-sensitive strain.

PURPOSE: Elucidate the ocular reactivation of HSV-1 strain F(MP)E. METHODS: Rabbit corneas were infected with HSV-1 strains McKrae and F(MP)E. Latency was established and rabbits were treated with epinephrine iontophoresis or corticosteroid injection (immunosuppression). Cultured tear films were used to determine the presence of infectious virus. Eyes of immunosuppressed rabbits were also examined by slit lamp biomicroscopy. Trigeminal ganglia were co-cultured on indicator cells at time of sacrifice for detection of virus. Quantitative real-time PCR was used to detect the number of viral genome copies in the trigeminal ganglia. RESULTS: Acute infections by strains McKrae and F(MP)E were the same. Ocular reactivation of strain F(MP)E by epinephrine iontophoresis was significantly reduced compared to McKrae (P </= 0.0001), but was not significantly different from McKrae after corticosteroid injection (P > 0.29). Slit lamp examination following corticosteroid injection showed a correlation of recurrent herpetic lesions with infectious virus in tear film swabs for both McKrae and F(MP)E. Trigeminal ganglia from rabbits latently infected with each strain and each method of induced reactivation resulted in infectious virus (P >/= 0.69). Genome copies for both strains were present and were highly variable. CONCLUSIONS: HSV-1 strain F(MP)E has low reactivation following epinephrine iontophoresis compared to McKrae, but has high reactivation like McKrae in response to corticosteroids. The difference in reactivation following epinephrine iontophoresis is not due to a difference in the establishment of latency.

Adrenal Cortex Hormones↗

PubMedDate not supplied

An HSV-1 chimeric containing HSV-2 latency associated transcript (LAT) sequences has significantly reduced adrenergic reactivation in the rabbit eye model.

PURPOSE: Both HSV-1 and HSV-2 express LAT during viral latency. Previous studies indicated that deletion of either LAT impairs viral reactivation from latency, but that the HSV-1 LAT confers the ability to reactivate efficiently from trigeminal ganglia onto HSV-2. We sought to determine whether the HSV-2 LAT could function in the context of HSV-1. METHODS: A chimeric HSV-1 that expresses the HSV-2 LAT in place of both copies of its own LAT was constructed. A rescuant virus, in which the wild-type genotype was restored, was also constructed to demonstrate that any phenotypic differences between the mutant virus and wild-type virus were due to the introduced mutations rather than to inadvertent mutations elsewhere in the virus. All viruses were tested in vitro and in vivo (via inoculation of rabbit eyes and induction of reactivation via iontophoresis of epinephrine) to determine the ability of the HSV-2 LAT to substitute for the HSV-1 LAT during acute infection and reactivation from latency. RESULTS: Substitution of the HSV-2 LAT for the HSV-1 LAT had no effect on acute replication or on the ability of the virus to cause disease in the rabbit ocular model. The ability of the mutant virus to reactivate from latency was substantially impaired relative to wild-type HSV-1. CONCLUSIONS: The HSV-2 LAT cannot substitute for the HSV-1 LAT in promoting reactivation from HSV-1 latency from rabbit trigeminal ganglia. This is consistent with the LAT being the major determinant of site-specific HSV reactivation.

Animals↗

PubMedDate not supplied

Herpesvirus quiescence (QIF) in neuronal cells VI: Correlative analysis demonstrates usefulness of QIF-PC12 cells to examine HSV-1 latency, reactivation and genes implicated in its regulation.

PURPOSE: To compare the usefulness of the in vitro quiescently infected (QIF)-PC12 cell model(30) with the in vivo rabbit eye model of latency for the study of herpes simplex virus (HSV) genes implicated in reactivation from latency. METHODS: HSV-1 strains 17+/pR20.5/5 and 17+/pR20.5/5/LAT, that were previously constructed by insertion of genes encoding beta-galactosidase, green fluorescent protein (GFP) or the latency associated transcript (LAT) open reading frame in the U(S)5 region,(34) were used to examine viral growth and inducible reactivation in the two models. RESULTS: 17+/pR20.5/5 exhibited diminished reactivation phenotype when compared with wild type 17+ in neuronal cells (i.e., QIF-PC12 cell model) and the rabbit eye model of latency. 17+/pR20.5/5/LAT, which contains the deregulated LAT gene, reactivated at wild type levels. Analysis of growth in neurally differentiated (ND)-PC12 cells demonstrated a low proportion of QIF cells expressed virus-encoded signals during the quiescent infection and a direct relationship between lytic viral growth in neuronal cells and reactivation phenotype. Even though 17+/pR20.5/5/LAT produced a more severe acute infection in the rabbit cornea, the different reactivation efficiency of 17+/pR20.5/5 and 17+/pR20.5/5/LAT in vivo and in vitro was not attributed to different viral genome copy number in the cells harboring cryptic genomes. CONCLUSIONS: We conclude that 1) viral growth in neuronal cells correlates with reactivation phenotype in vivo and in vitro, 2) 17+/pR20.5/5 is attenuated in viral growth and reactivation in both models, and 3) 17+/pR20.5/5/LAT demonstrates wild-type phenotype for reactivation in both models. Attenuation of 17+/pR20.5/5 could be the result of the disruption of U(S)5 or a second site mutation. If the attenuation is the result of U(S)5 disruption, a gene that provides anti-apoptotic functions,( 41,42) this attenuation is more than compensated for by the expression of the LAT ORF. Overall, the findings indicate that the QIF-PC12 cell model is useful for segregating phases of reactivation, and particularly studying the inductive events involved in reactivation of a cryptic viral genome in neurally differentiated cells.

Animals↗