Herpesvirus infection of the liver.

The human herpesviruses can produce a wide variety of disease in the liver (Table 7). The immunocompromised host is particularly susceptible to hepatic manifestations of herpesvirus disease. CMV is the most common opportunistic pathogen in the immunocompromised patient. The clinical presentation of hepatic herpesvirus infection is often nonspecific. A high index of suspicion and rapid progression to liver biopsy to document viral replication (alpha- and betaherpesviruses) or outgrowth of virus-infected cells (gammaherpesviruses) can lead to lifesaving therapeutic interventions.

Use of physiatry as the sole treatment for three paretic or paralyzed dogs with chronic compressive conditions of the caudal portion of the cervical spinal cord.

Physiatry alone was used to treat 3 large (30- to 40-kg [66 to 88 lb]) mature (6- to 9-year-old) dogs that were tetraparetic or tetraplegic. All 3 dogs had myelographic evidence of multiple chronic compressive extradural lesions of the caudal portion of the cervical spinal cord. All dogs improved substantially after a course of intensive physical treatment. For 2 dogs, an abbreviated treatment regimen was continued by the owners after the dogs were discharged. Both of these dogs regained and retained normal neurologic function. The other dog improved but was treated infrequently at home. That dog's signs recurred, and the dog was euthanatized. Persistent use of physical treatment for paralysis that results from conditions affecting the cervical spinal cord may be useful even without concurrent surgical or pharmacologic treatments.

Characterization of an acyclovir-resistant herpes simplex virus type 2 strain isolated from a premature neonate.

Acyclovir resistance is not a recognized problem among neonates with perinatal herpes simplex virus (HSV) infection. A premature newborn with neurocutaneous HSV infection was treated for 21 days with acyclovir. Disseminated disease recurred 8 days later. A recurrent isolate was resistant to acyclovir and lacked thymidine kinase activity on the basis of a frameshift mutation in the thymidine kinase (tk) gene. Compared with the sensitive isolate obtained during primary infection, replication of the resistant isolate was reduced on primary and permanent cells and even further impaired on cells deleted for cellular tk. The resistant isolate lacked virulence in a murine model of genital infection. Acyclovir-resistant HSV-2 mutants can develop rapidly in neonatal infection and cause clinically significant disease, despite decreased replication in vitro and attenuated virulence in an animal model.

Human herpesvirus 8 open reading frame 21 is a thymidine and thymidylate kinase of narrow substrate specificity that efficiently phosphorylates zidovudine but not ganciclovir.

Human herpesvirus 8 (HHV8) open reading frame (ORF) 21 is predicted to encode a protein similar to the thymidine kinase (TK) enzyme of other herpesviruses. Expressed in mammalian cells, ORF 21 was found to have low TK activity, based on poor growth in media containing hypoxanthine-aminopterin-thymidine (HAT) and low incorporation of [(3)H]thymidine into high-molecular-weight DNA. Kinetic analysis using HHV8 TK as a purified glutathione S-transferase (GST) fusion protein showed that the enzyme has a comparatively high K(m) for thymidine (dThd) of approximately 33.2 microM. Nearly 50% of the phosphorylated product of the reaction with dThd was thymidylate. This monophosphate kinase activity was more pronounced with 3'-azido-3'-deoxythymidine (AZT), in which 78% of the reaction product was AZT diphosphate. Thymidine analogs competitively inhibited dThd phosphorylation by HHV8 TK, while 2'-deoxyguanosine, 2'-deoxyadenosine, 2'-deoxycytidine, and corresponding analogs did not. Further competition experiments revealed that the nucleoside analog ganciclovir (GCV), at up to 1,000-fold molar excess, could not significantly inhibit dThd phosphorylation by the enzyme. In support of these data, 143B TK(-) cells expressing HHV8 TK phosphorylated GCV very poorly and were not susceptible to GCV toxicity compared to parental cells. Phosphorylation of [(3)H]GCV by a purified GST-HHV8 TK fusion protein was not detected by high-pressure liquid chromatography analysis. Structural features of HHV8 TK substrate recognition were investigated. Therapeutic implications of these findings are discussed.

Epstein-Barr virus encodes a novel homolog of the bcl-2 oncogene that inhibits apoptosis and associates with Bax and Bak.

The sequenced gammaherpesviruses each contain a single viral bcl-2 homolog (v-bcl-2) which may encode a protein that functions in preventing the apoptotic death of virus-infected cells. Epstein-Barr virus (EBV), a gammaherpesvirus associated with several lymphoid and epithelial malignancies, encodes the v-Bcl-2 homolog BHRF1. In this report the previously uncharacterized BALF1 open reading frame in EBV is identified as having significant sequence similarity to other v-bcl-2 homologs and cellular bcl-2. Transfection of cells with a BALF1 cDNA conferred apoptosis resistance. Furthermore, a recombinant green fluorescent protein-BALF1 fusion protein suppressed apoptosis and associated with Bax and Bak. These results indicate that EBV encodes a second functional v-bcl-2.

CD21-Dependent infection of an epithelial cell line, 293, by Epstein-Barr virus.

Epstein-Barr virus (EBV) is invariably present in undifferentiated nasopharyngeal carcinomas, is found sporadically in other carcinomas, and replicates in the differentiated layer of the tongue epithelium in lesions of oral hairy leukoplakia. However, it is not clear how frequently or by what mechanism EBV infects epithelial cells normally. Here, we report that a human epithelial cell line, 293, can be stably infected by EBV that has been genetically marked with a selectable gene. We show that 293 cells express a relatively low level of CD21, that binding of fluorescein-labeled EBV to 293 cells can be detected, and that both the binding of virus to cells and infection can be blocked with antibodies specific for CD21. Two proteins known to form complexes with CD21 on the surface of lymphoid cells, CD35 and CD19, could not be detected at the surface of 293 cells. All infected clones of 293 cells exhibited tight latency with a pattern of gene expression similar to that of type II latency, but productive EBV replication and release of infectious virus could be induced inefficiently by forced expression of the lytic transactivators, R and Z. Low levels of mRNA specific for the transforming membrane protein of EBV, LMP-1, as well as for LMP-2, were detected; however, LMP-1 protein was either undetectable or near the limit of detection at less than 5% of the level typical of EBV-transformed B cells. A slight increase in expression of the receptor for epidermal growth factor, which can be induced in epithelial cells by LMP-1, was detected at the cell surface with two EBV-infected 293 cell clones. These results show that low levels of surface CD21 can support infection of an epithelial cell line by EBV. The results also raise the possibility that in a normal infection of epithelial cells by EBV, the LMP-1 protein is not expressed at levels that are high enough to be oncogenic and that there might be differences in the cells of EBV-associated epithelial cancers that have arisen to allow for elevated expression of LMP-1.

Detection of Kaposi's sarcoma herpesvirus DNA sequences in multiple myeloma bone marrow stromal cells.

Whether Kaposi's sarcoma herpesvirus (KSHV) is associated with multiple myeloma (MM) remains controversial. We assayed for KSHV DNA sequences in long-term bone marrow stromal cells (BMSCs) from 26 patients with MM and 4 normal donors. Polymerase chain reaction (PCR) using primers which amplify a KSHV gene sequence to yield a 233-bp fragment (KS330233 within open reading frame 26) was negative in all cases. Aliquots of these PCR products were used as templates in subsequent nested PCR, with primers that amplify a 186-bp product internal to KS330233. BMSCs from 24 of 26 (92%) patients with MM and 1 of 4 normal donors were KSHV PCR+. DNA sequence analyses showed interpatient specific mutations (2 to 3 bp). Both Southern blot and sequence analyses confirmed the specificity of PCR results. The presence of the KSHV gene sequences was further confirmed by amplifying T 1.1 (open reading frame [ORF] K7) and viral cyclin D (ORF 72), two other domains within the KSHV genome. Immunohistochemical studies of KSHV PCR+ MM BMSCs demonstrate expression of dendritic cell (DC) lineage markers (CD68, CD83, and fascin). Serological studies for the presence of KSHV lytic or latent antibodies were performed using sera from 53 MM patients, 12 normal donors, and 5 human immunodeficiency virus (HIV)/KSHV+ patients. No lytic or latent antibodies were present in sera from either MM patients or normal donors. Taken together, these findings show that KSHV DNA sequences are detectable in BMSCs from the majority of MM patients, but that serologic responses to KSHV are not present. Ongoing studies are defining whether the lack of antibody response is caused by the absence of ongoing infection, the presence of a novel viral strain associated with MM, or underlying immunodeficiency in these patients.

The Epstein-Barr virus thymidine kinase does not phosphorylate ganciclovir or acyclovir and demonstrates a narrow substrate specificity compared to the herpes simplex virus type 1 thymidine kinase.

The Epstein-Barr virus (EBV) thymidine kinase (TK) was expressed in mammalian 143B TK- cells to investigate its substrate specificity. The herpes simplex virus type 1 (HSV-1) TK was similarly expressed for comparison. Both viral TKs conferred a TK+ phenotype on 143B TK- cells. The nucleoside analog ganciclovir (GCV) did not affect the growth of 143B EBV TK or 143B TK- cells but effectively killed 143B HSV-1 TK cells. Furthermore, lysates of 143B EBV TK cells could not phosphorylate GCV, which was confirmed by high-performance liquid chromatography. EBV TK, HSV-1 TK, and EBV TK N-, a truncated EBV TK missing 243 N-terminal amino acids, were purified as fusion proteins expressed in bacteria, and all had TK activity. In addition, EBV TK was observed to have a thymidylate kinase activity but could not phosphorylate GCV, acyclovir, or 2'-deoxycytidine. In competition assays, only nucleoside analogs of thymidine significantly inhibited thymidine phosphorylation by EBV TK, with the following rank order: 5-bromodeoxyuridine > zidovudine > stavudine > sorivudine. These results demonstrate that EBV TK substrate specificity is narrower than those of alphaherpesvirus TKs and that thymidine analogs may be the most suitable nucleoside antivirals to target the enzyme. Clinical implications for gammaherpesviruses are discussed.

A versatile prokaryotic cloning vector with six dual restriction enzyme sites in the polylinker facilitates efficient subcloning into vectors with unique cloning sites.

In large and complex vectors a single restriction enzyme recognition site may be available for introduction of additional DNA requiring the development of linker fragments to create compatible insertion sites. This technology can be time consuming and costly. We describe the construction of a simple phagemid, pSFI, with a polylinker that contains six pairs of dual, rare-cutting, restriction enzyme recognition sites (NotI, SpeI, EcoRV, PstI, SacII, EagI) with multiple unique sites between each pair. This has permitted rapid subcloning of DNA with creation of single flanking restriction enzyme sites. pSFI was used to expedite transfer of viral genes to a LacZ-inducible expression vector and to an adenovirus expression cassette for production of replication-defective virus. The use of this phagemid has facilitated complex vector manipulations and is a valuable adjunct to the family of multifunctional cloning vectors.

Arginine butyrate-induced susceptibility to ganciclovir in an Epstein-Barr-virus-associated lymphoma.

Lymphoproliferative disorders associated with Epstein-Barr virus (EBV) infections can occur in the setting of immunosuppression. In some patients, the lymphoproliferative disorder can resemble an aggressive monoclonal non-Hodgkins lymphoma (NHL). These NHL are poorly responsive to conventional therapy. Similarly, antiviral therapy with synthetic nucleosides such as ganciclovir are ineffective because the genes that render the virus susceptible to therapy are not expressed in EBV+ lymphomas. Using a cell line derived from a lung transplant recipient with an EBV+ immunoblastic NHL, we studied the ability of arginine butyrate to induce the expression of EBV thymidine kinase. Arginine butyrate was not only effective in inducing EBV thymidine kinase transcription, but also acted synergistically with the antiviral agent ganciclovir to inhibit cell proliferation and decrease cell viability. Based on these findings, the patient from whom the cell line was derived was treated with arginine butyrate/ganciclovir as well as conventional cytotoxic chemotherapy. No additional toxicity was observed with the arginine butyrate/ganciclovir therapy. Histologic examination of the tumor showed substantial necrosis. These observations suggest the feasibility of arginine butyrate induction of ganciclovir susceptibility in patients with EBV-associated lymphomas.

IGIV: a potential role for hepatitis B prophylaxis in the bone marrow peritransplant period.

Prevention of hepatitis B virus infection in transplant recipients can be difficult. Patients may be unresponsive to vaccination and intolerant of the intramuscular injections required to administer hepatitis B immune globulin (HBIG). A recipient of HBsAg-positive donor cells for a bone marrow transplant received multiple i.m. injections of HBIG. This mode of antibody delivery was limited by his thrombocytopenia and neutropenia and alternative forms of passive immunization were sought. Four lots of IGIV were investigated for anti-hepatitis B surface antibody (anti-HBs) content and all were found to contain significant antibody titer. Moreover, IGIV that was administered to four bone marrow transplant recipients for medical purposes unrelated to HBV transmission produced protective anti-HBs titers in all. These studies suggest IGIV may be useful for HBV prophylaxis in the appropriate setting or if HBIG is unavailable. The optimum regimen for HBV prevention in distinct transplant settings needs to be determined.

Prevention of transmission of hepatitis C virus in bone marrow transplantation by treating the donor with alpha-interferon.

Transmission of hepatitis C virus (HCV) in the setting of allogeneic bone marrow transplantation can occur through an infected marrow donor. Prevention of transmission may reduce the risks of peritransplant complications. We describe a 43-year-old patient with chronic myelogenous leukemia whose HLA-identical donor was found to be HCV antibody positive and HCV RNA positive by polymerase chain reaction (PCR). The patient was HCV antibody negative and HCV RNA negative by PCR of the serum. For 6 months before bone marrow transplantation, the donor was treated with alpha-interferon at a standard dose. After 3 months, HCV RNA was no longer detectable by PCR. Interferon was discontinued 1 week before harvest. Bone marrow cellularity was normal. Engraftment was prompt. The recipient's serum remained negative for HCV RNA at 1, 3, 5, and 10 months after transplantation. Hepatitis C transmission from a viremic donor to an HCV-seronegative recipient may be preventable by treating the donor with alpha-interferon.

Immunoblastic lymphoma of donor origin in the allograft after lung transplantation.

Posttransplant lymphoproliferative disorders (PTLD) are EBV-associated lymphoid neoplasms that are caused by the uncontrolled growth of EBV-infected B lymphocytes. The clinical presentation of PTLD can range from benign polygonal lymphoproliferative disorders to aggressive monoclonal immunoblastic lymphomas. In this report, we describe a seronegative lung transplant recipient who developed an immunoblastic lymphoma 4 months after lung transplantation from a seropositive donor. The neoplastic cells expressed B lymphocyte markers (CD19+, CD20+, sIgM+, kappa+) as well as the EBV antigen EBNA-2. A cell line with similar cytologic features spontaneously grew from in vitro cultures of the patient's peripheral blood mononuclear cells. The cell line and the lymphoma were EBV+, expressed a similar spectrum of B cell surface proteins, and had the donor's HLA haplotype. Analysis of immunoglobulin gene rearrangements and viral terminal repeat sequences revealed that the cell line and the tumor represented distinct B cell clones. Cultured peripheral blood mononuclear cells were restimulated in vitro with the EBV transformed cell line and tested for cytolytic activity. The host T cells demonstrated high levels of cytolytic activity against the tumor cell line that was abrogated by the addition of a anti-monomorphic HLA class I monoclonal antibody (mAb) (W6/32). These studies indicate that cells of donor origin can persist in the transplanted organ and may lead to an EBV-associated posttransplant lymphoma.

Expression of recombination activating genes (RAG-1 and RAG-2) in Epstein-Barr virus-bearing B cells.

Recombination activating genes 1 and 2 (RAG-1 and RAG-2), are the only lymphoid-specific genes required for the site-directed recombination reaction leading to generation of B-cell receptors and T-cell receptors (TCRs). RAGs are normally expressed during a narrow window of precursor lymphocyte development. RAG expression was examined in Epstein-Barr virus (EBV)-infected B cells. No steady-state RAG RNA was found in EBV immortalized cells, including newly established B lymphoblastoid cell lines derived from precursor lymphocytes that transcribed RAGs at the time of infection. RAG RNAs were detected in some endemic (EBV+) and also in some sporadic (EBV-) Burkitt's lymphoma lines that had been infected with EBV in vitro. The RAG+, EBV+ Burkitt's lines were unusual in that they were SIgM+ (one was SIgG+, SIgM-), CD10+, and lacked terminal deoxynucleotidyl transferase. In EBV+ Burkitt's lymphoma lines, transcription of virus latent membrane protein-1 (LMP-1) was correlated with downregulation of RAG-1 and RAG-2. Conversely, absence of LMP-1 in clones of EBV+ tumor lines was associated with increased RAG transcription. Translocation of c-myc into V(D)J loci has been observed in endemic Burkitt's lymphomas, and heptamer-nonamer recombination signal sequences have been identified at some chromosomal breakpoints. Association of RAG transcription with EBV infection raises the possibility that, under certain conditions, virus might predispose to aberrant V(D)J recombination reactions.

Marrow transplantation from hepatitis C virus seropositive donors: transmission rate and clinical course.

Bone marrow transplant recipients are at risk for acquiring hepatitis C infection from the donated marrow. Twelve patients who were hepatitis C virus (HCV) RNA-negative pretransplant received marrow from anti-HCV seropositive donors. HCV RNA was present in the sera of seven of these donors. After transplant, serial serum specimens were obtained from all marrow recipients for determination of HCV RNA and aminotransferase levels. All seven recipients of marrow from HCV RNA-positive donors were HCV RNA-positive after marrow infusion; none cleared virus from the serum. All five recipients of marrow from anti-HCV seropositive, HCV RNA-negative donors remained free of HCV RNA in serum up to day 100. Abnormal serum aminotransferases were common in both HCV RNA-negative and HCV RNA-positive marrow recipients. One HCV-infected recipient developed marked elevation in aminotransferases after immunosuppressive drugs were stopped. We conclude that the presence of HCV RNA in the serum of marrow donors is an accurate predictor of HCV infection in marrow recipients. The acute infection was subclinical in all patients. The long-term risk of chronic hepatitis C virus infection in these patients remains to be determined.

Zygomycosis due to Mucor circinelloides in a neutropenic patient receiving chemotherapy for acute myelogenous leukemia.

Mucor circinelloides form circinelloides has rarely been associated with human disease, even in immunocompromised patients. We report a case of cutaneous zygomycosis caused by M. circinelloides in a 23-year-old neutropenic woman receiving consolidation chemotherapy for acute myelogenous leukemia. The organism was exquisitely susceptible to amphotericin B. Despite the fact that the patient was profoundly neutropenic for an additional 3 weeks, the lesions began to resolve during therapy, and no surgical debridement was required.

Role of interleukin 6 in the growth of myeloma-derived cell lines.

The role of interleukin 6 (IL-6) in the growth of five multiple myeloma-derived cell lines was characterized. The U266 and RPMI 8226 cell lines demonstrated increased DNA synthesis when cultured with exogenous IL-6, expressed IL-6 cell surface receptors (IL-6Rs) and expressed mRNA for IL-6R. However, these cells did not secrete detectable IL-6 protein, and a neutralizing antibody to IL-6 did not inhibit their growth. Three other myeloma-derived cell lines ARH-77, IM-9 and HS-Sultan did not respond to exogenous IL-6, secrete IL-6 or express cell surface IL-6Rs. The IL-6 responsive cell lines bore late B-cell surface antigens (Ags), CD38 and PCA-1, whereas those lines which were non-IL-6 responsive strongly expressed B1 (CD20) and B4 (CD19) Ags, representing earlier stages in B-cell differentiation. Finally, the two IL-6 responsive cell lines did not express Epstein-Barr virus (EBV) proteins; in contrast, EBV encoded proteins typically expressed during latency could be detected in the three non-IL-6 responsive lines, confirming infection with virus. These studies clarify the heterogeneity observed in the myeloma cell line phenotype and biology and suggest that the U266 and RPMI 8226 cell lines, which express IL-6 cell surface receptors and are IL-6 responsive, may be useful for further study of IL-6 signal transduction in and related IL-6 mediated growth of myeloma in vivo. In contrast, those cell lines which are IL-6-independent provide a model for further study of EBV transformation and IL-6-dependent growth mechanisms in malignancy.

Structure, expression, and T cell costimulatory activity of the murine homologue of the human B lymphocyte activation antigen B7.

Following occupancy of the T cell receptor by antigen, T cell proliferation and lymphokine production are determined by a second costimulatory signal delivered by a ligand expressed on antigen presenting cells. The human B cell activation antigen B7, which is expressed on antigen presenting cells including activated B cells and gamma interferon treated monocytes, has been shown to deliver such a costimulatory signal upon attachment to its ligand on T cells, CD28. We have cloned and sequenced the murine homologue of the human B7 gene. The predicted murine protein has 44% amino acid identity with human B7. The greatest similarity is in the Ig-V and Ig-C like domains. Murine B7 mRNA was detected in murine hematopoietic cells of B cell but not T cell origin. Cells transfected with murine B7 provided a costimulatory signal to human CD28+ T lymphocytes. These results demonstrate the costimulatory activity of murine B7 and provide evidence that the ligand attachment site is conserved between the two species.