Biomedical subjects

Philip Krause

Publications and source records attributed to Philip Krause.

3 recordsLinked to original sources

PubMed2004

Simian cytomegalovirus encodes five rapidly evolving chemokine receptor homologues.

Many herpesviruses, poxviruses and retroviruses encode proteins related to chemokines and chemokine receptors. The first one discovered, US28 of human cytomegalovirus (HCMV), is a 7-transmembrane domain G protein-coupled chemokine receptor able to activate diverse cellular responses, including cell migration and gene expression. A related ORF named US27 is adjacent to US28, but no functions have been defined yet. Recently ORFs 3-7, a cluster of five concatenated ORFs with highest homology to US28 and mammalian chemokine receptors, were sequenced from a prototype "stealth virus", an African green monkey simian CMV (SCMV)-related entity with unusual fungal, bacterial and mammalian gene homologues. Stealth viruses have not yet been independently replicated in tissue culture, and therefore their biological significance remains unclear. ORF3, ORF4, ORF5 and ORF6 are complete ORFs whereas the sequence of ORF7 is incomplete. In the present study, we identified five corresponding ORFs in the genome of a clinical isolate of bonafide simian CMV (SCMV), strain 9610. We found substantial differences between the SCMV and "stealth virus" ORFs, especially for ORF5 where there are 31% non-identities at the amino acid level. Four conserved genes unrelated to chemokines (64K/CAP, DNBI, UL32, and IE2) in SCMV and HCMV had on average 52% identity at the deduced amino acid level, whereas the corresponding values for the SCMV ORFs versus US28 ranged from 21% to 30%, suggesting rapid gene diversification in this cluster. Consistent with this, the amino acid identity for any pairwise comparison among the SCMV ORFs is only 21-52%. The chemokine receptor homologues are estimated to comprise approximately 2-3% of the SCMV genome. HCMV US27 and US28 homologues have also been identified in the chimpanzee CMV genome, whereas mouse and rat CMV lack chemokine receptor homologues. This genomic analysis indicates that SCMV has an unusually high concentration of US28-related chemokine receptor homologues that have arisen by gene duplication and have diverged extensively from their closest relatives in mammals and other beta herpesviruses. The rate of divergence appears to be very rapid compared to other known SCMV genes, suggesting strong positive selection.

Amino Acid Sequence↗

PubMed2002

Spontaneous molecular reactivation of herpes simplex virus type 1 latency in mice.

Infection of the mouse trigeminal ganglia (TG) is the most commonly used model for the study of herpes simplex virus type 1 (HSV-1) latency. Its popularity is caused, at least in part, by the perception that latent infection can be studied in this system in the absence of spontaneous viral reactivation. However, this perception has never been rigorously tested. To carefully study this issue, the eyes of Swiss-Webster mice were inoculated with HSV-1 (KOS), and 37-47 days later the TG were dissected, serial-sectioned, and probed for HSV-1 ICP4, thymidine kinase, glycoprotein C, and latency-associated transcript RNA by in situ hybridization. Serial sections of additional latently infected TG were probed with HSV-1-specific polyclonal antisera. Analysis of thousands of probed sections revealed abundant expression of viral transcripts, viral protein, and viral DNA replication in about 1 neuron per 10 TG tested. These same neurons were surrounded by a focal white cell infiltrate, indicating the presence of an antigenic stimulus. We conclude that productive cycle viral genes are abundantly expressed in rare neurons of latently infected murine TG and that these events are promptly recognized by an active local immune response. In the absence of detectable infectious virus in these ganglia, we propose the term "spontaneous molecular reactivation" to describe this ongoing process.

Animals↗

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↗