Dana G. Wolf

Inhibition of the NKp30 activating receptor by pp65 of human cytomegalovirus

Human cytomegalovirus, a chief pathogen in immunocompromised people, can persist in a healthy immunocompetent host throughout life without being eliminated by the immune system. Here we show that pp65, the main tegument protein of human cytomegalovirus, inhibited natural killer cell cytotoxicity by an interaction with the activating receptor NKp30. This interaction was direct and specific, leading to dissociation of the linked CD3ζ from NKp30 and, consequently, to reduced killing. Thus, pp65 is a ligand for the NKp30 receptor and demonstrates a unique mechanism by which an intracellular viral protein causes general suppression of natural killer cell cytotoxicity by specific interaction with an activating receptor.

The Antiviral Activities of Artemisinin and Artesunate

Traditional Chinese medicine commands a unique position among all traditional medicines because of its 5000 years of history. Our own interest in natural products from traditional Chinese medicine was triggered in the 1990s, by artemisinin-type sesquiterpene lactones from Artemisia annua L. As demonstrated in recent years, this class of compounds has activity against malaria, cancer cells, and schistosomiasis. Interestingly, the bioactivity of artemisinin and its semisynthetic derivative artesunate is even broader and includes the inhibition of certain viruses, such as human cytomegalovirus and other members of the Herpesviridae family (e.g., herpes simplex virus type 1 and Epstein-Barr virus), hepatitis B virus, hepatitis C virus, and bovine viral diarrhea virus. Analysis of the complete profile of the pharmacological activities and molecular modes of action of artemisinin and artesunate and their performance in clinical trials will further elucidate the full antimicrobial potential of these versatile pharmacological tools from nature.

Comparison of human metapneumovirus, respiratory syncytial virus and influenza a virus lower respiratory tract infections in hospitalized young children

Background: We compared the clinical and demographic features of children with lower respiratory tract infection (LRI) caused by human metapneumovirus (HMPV), respiratory syncytial virus (RSV) and influenza A virus and sought to determine whether coinfection by HMPV and other respiratory viruses leads to increased disease severity. Methods: Nasal wash specimens were prospectively obtained from 516 children hospitalized for LRI during a 1-year period and tested for the presence of HMPV by reverse transcription-polymerase chain reaction and for RSV and influenza A by direct immunofluorescence. Results: HMPV was detected in 68 (13%) patients and was the third most common viral pathogen; 16 of 68 HMPV-positive children (24%) had coinfection with other respiratory viruses (HMPVco). HMPV patients were older than RSV patients (17.6 ± 16.8 months versus 10.5 ± 11.8 months, P = 0.02). HMPV was associated with wheezing and hypoxemia at a rate similar to that of RSV and higher than that of influenza A. Atelectasis was more common among HMPV (40%) than among RSV and influenza patients (13%, P < 0.05 for each). HMPV infection was more often associated with a diagnosis of pneumonia than RSV and influenza A and was more often associated with a diagnosis of asthma and less often associated with a diagnosis of bronchiolitis than RSV infection (P < 0.05 for each), even when corrected for age. Children with HMPVco had a higher rate of gastrointestinal symptoms but did not show a more severe respiratory picture. Conclusions: The clinical pattern of HMPV more closely resembles that of RSV than that of influenza A LRI, yet the differences in age, radiographic findings and clinical diagnosis suggest that HMPV pathogenesis may differ from that of RSV.

Mutations in human cytomegalovirus UL97 gene confer clinical resistance to ganciclovir and can be detected directly in patient plasma.

Specific mutations in the UL97 region of human cytomegalovirus (HCMV) have been found to confer resistance to laboratory-adapted strains subjected to ganciclovir selection. In this study, mutations in the UL97 region of HCMV isolates obtained from patients receiving ganciclovir therapy were examined to determine whether they would confer ganciclovir resistance, and if these mutations could be detected directly in the plasma of AIDS patients with progressive HCMV disease despite ganciclovir treatment. A single nucleotide change within a conserved region of UL97 was found in five resistant isolates, resulting in an amino acid substitution in residue 595: from leucine to phenylalanine in one, and from leucine to serine in four resistant isolates. A sixth resistant isolate demonstrated a single nucleotide change, leading to a threonine to isoleucine substitution in residue 659. The role of the 595 amino acid substitution in conferring ganciclovir resistance was confirmed by marker transfer experiments. In further studies, direct sequencing of HCMV DNA present in plasma obtained from persons with resistant viruses revealed the identical amino acid substitutions in plasma as those present in the cultured viruses. These findings indicate that clinical resistance to ganciclovir can result from specific point mutations in the UL97 gene, and that the emergence of the resistant genotype can be detected directly in patient plasma.

Global Genetic Diversity of Human Metapneumovirus Fusion Gene

We analyzed 64 human metapneumovirus strains from eight countries. Phylogenetic analysis identified two groups (A and B, amino acid identity 93%–96%) and four subgroups. Although group A strains predominated, accounting for 69% of all strains, as many B as A strains were found in persons >3 years of age.

The human cytomegalovirus microRNA miR-UL112 acts synergistically with a cellular microRNA to escape immune elimination

Although approximately 200 viral microRNAs are known, only very few share similar targets with their hosts microRNAs. A notable example of this is the stress-induced ligand MICB, which is targeted by several distinct viral and cellular microRNAs. Through the investigation of the microRNA-mediated immune-evasion strategies of herpesviruses, we initially identified two new cellular microRNAs that targeted MICB and were expressed differently both in healthy tissues and during melanocyte transformation. We show that coexpression of various pairs of cellular microRNAs interfered with the downregulation of MICB, whereas the viral microRNAs optimized their targeting ability to efficiently downregulate MICB. Moreover, we demonstrate that through site proximity and possibly inhibition of translation, a human cytomegalovirus (HCMV) microRNA acts synergistically with a cellular microRNA to suppress MICB expression during HCMV infection.

Pivotal role of CEACAM1 protein in the inhibition of activated decidual lymphocyte functions

Lymphocytes in direct contact with embryonic extravillous trophoblasts constitute more than 40% of decidual cells and appear to play major roles in implantation and early gestation. A unique subset of NK cells, making up 70-80% of decidual lymphocytes, express high levels of CD56 but lack CD16. We have recently demonstrated a novel class I MHC-independent inhibitory mechanism of NK cell cytotoxicity that is mediated by CEACAM1 homotypic interactions. This mechanism is used by some melanoma cells to avoid attack, mainly by CD16(-) NK cells. We now demonstrate that CEACAM1 is expressed on primary extravillous trophoblasts and is upregulated on the vast majority of IL-2-activated decidual lymphocytes, including NK, T, and NKT cells. Importantly, we present evidence that CEACAM1 interactions inhibit the lysis, proliferation, and cytokine secretion of activated decidual NK, T, and NKT cells, respectively. In vivo analysis of decidual lymphocytes isolated from cytomegalovirus-infected (CMV-infected) pregnant women revealed a dramatic increase in the expression of CEACAM1. Finally, we suggest that a novel ligand for this adhesion molecule is present on the surface of CMV-infected fibroblasts. These combined results demonstrate a major role for the CEACAM1 protein in controlling local decidual immune responses.

Artesunate as a Potent Antiviral Agent in a Patient with Late Drug-Resistant Cytomegalovirus Infection after Hematopoietic Stem Cell Transplantation

This is the first report of treatment of cytomegalovirus infection with artesunate, for a stem cell transplant recipient with a newly identified foscarnet-resistant and ganciclovir-resistant DNA polymerase L776M mutation. Artesunate treatment resulted in a 1.7-2.1-log reduction in viral load by treatment day 7, with a viral half-life of 0.9-1.9 days, indicating a highly effective block in viral replication.

Multidrug-resistant Trichosporon asahii infection of nongranulocytopenic patients in three intensive care units.

ABSTRACT Trichosporon asahii (Trichosporon beigelii) infections are rare but have been associated with a wide spectrum of clinical manifestations, ranging from superficial involvement in immunocompetent individuals to severe systemic disease in immunocompromised patients. We report on the recent recovery ofT. asahii isolates with reduced susceptibility in vitro to amphotericin B (AMB), flucytosine, and azoles from six nongranulocytopenic patients who exhibited risk factors and who developed either superficial infections (four individuals) or invasive infections (two individuals) while in intensive care units. The latter two patients responded clinically and microbiologically to AMB treatment. All six isolates were closely related according to random amplified polymorphic DNA studies and showed 71% similarity by amplified fragment length polymorphism analysis, suggesting a common nosocomial origin. We also review the literature pertaining toT. asahii infections and discuss the salient characteristics of this fungus and recent taxonomic proposals for the genus.

High Seroprevalence of Human Metapneumovirus among Young Children in Israel

Exposure to the newly discovered human metapneumovirus (HMPV) during the first 2 years of life was studied by longitudinal serological analysis in 40 healthy children in southern Israel. The seropositivity rate decreased to a minimum by age 13 months and increased to 52% by age 24 months. Evidence of new infection was detected in 13%, 23%, and 55% of children by ages 7, 13, and 24 months, respectively. The high exposure rates suggest that HMPV may be an important cause of community-acquired respiratory-tract infections in young children.