Multiple organ infection and the pathogenesis of SARS

After >8,000 infections and >700 deaths worldwide, the pathogenesis of the new infectious disease, severe acute respiratory syndrome (SARS), remains poorly understood. We investigated 18 autopsies of patients who had suspected SARS; 8 cases were confirmed as SARS. We evaluated white blood cells from 22 confirmed SARS patients at various stages of the disease. T lymphocyte counts in 65 confirmed and 35 misdiagnosed SARS cases also were analyzed retrospectively. SARS viral particles and genomic sequence were detected in a large number of circulating lymphocytes, monocytes, and lymphoid tissues, as well as in the epithelial cells of the respiratory tract, the mucosa of the intestine, the epithelium of the renal distal tubules, the neurons of the brain, and macrophages in different organs. SARS virus seemed to be capable of infecting multiple cell types in several organs; immune cells and pulmonary epithelium were identified as the main sites of injury. A comprehensive theory of pathogenesis is proposed for SARS with immune and lung damage as key features.

A new phlebovirus associated with severe febrile illness in Missouri

Two men from northwestern Missouri independently presented to a medical facility with fever, fatigue, diarrhea, thrombocytopenia, and leukopenia, and both had been bitten by ticks 5 to 7 days before the onset of illness. Ehrlichia chaffeensis was suspected as the causal agent but was not found on serologic analysis, polymerase-chain-reaction (PCR) assay, or cell culture. Electron microscopy revealed viruses consistent with members of the Bunyaviridae family. Next-generation sequencing and phylogenetic analysis identified the viruses as novel members of the phlebovirus genus. Although Koch's postulates have not been completely fulfilled, we believe that this phlebovirus, which is novel in the Americas, is the cause of this clinical syndrome.

Cytomegalovirus remains latent in a common precursor of dendritic and myeloid cells

Hematopoietic cells and their progenitors play important roles in human cytomegalovirus latency and reactivation. Latent infection has been evaluated in defined populations of myeloid-lineage-committed progenitor cells coexpressing CD33 and CD15 or CD33 and CD14 along with the dendritic cell markers CD1a and CD10. These CD33+ cell populations were found to support latency and expression of viral latency-associated transcripts and to undergo reactivation of productive viral replication when differentiated in the presence of human fibroblasts. Reactivation was also observed when myeloid cells were carried in the presence of fibroblast-conditioned medium or medium supplemented with certain cytokines (interferon gamma, tumor necrosis factor alpha, interleukin 4, or granulocyte-macrophage colony-simulating factor), suggesting that cell differentiation pathways act as determinants of reactivation. More primitive CD34+ hematopoietic cells were also found to be susceptible to viral infection and latency was maintained as these cells differentiated into CD33+-lineage-committed populations. Between 0.01% and 0.001% of CD33+ CD14+ or CD33+ CD15+ bone marrow mononuclear cells isolated from naturally infected individuals were found to express latent transcripts. Thus, cytomegalovirus is carried within a small percentage of myeloid and dendritic cell progenitors in the healthy seropositive host. Virus reactivation may be triggered by factors associated with the inflammatory response.

Human cytomegalovirus UL131-128 genes are indispensable for virus growth in endothelial cells and virus transfer to leukocytes

Human cytomegalovirus (HCMV), a ubiquitous human pathogen, is the leading cause of birth defects and morbidity in immunocompromised patients and a potential trigger for vascular disease. HCMV replicates in vascular endothelial cells and drives leukocyte-mediated viral dissemination through close endothelium- leukocyte interaction. However, the genetic basis of HCMV growth in endothelial cells and transfer to leukocytes is unknown. We show here that the UL131-128 gene locus of HCMV is indispensable for both productive infection of endothelial cells and transmission to leukocytes. The experimental evidence for this is based on both the loss-of-function phenotype in knockout mutants and natural variants and the gain-of-function phenotype by trans-complementation with individual UL131, UL130, and UL128 genes. Our findings suggest that a common mechanism of virus transfer may be involved in both endothelial cell tropism and leukocyte transfer and shed light on a crucial step in the pathogenesis of HCMV infection.

Transcytosis of infectious human immunodeficiency virus across a tight human epithelial cell line barrier

Contact between various epithelial cell lines and HIV chronically infected mononuclear cell lines results in a massive and rapid budding of HIV virions toward the epithelium followed by their internalization into epithelial endosome-like structures. Here it is shown that as early as 30 minutes after apical contact, primary virus isolates generated from primary peripheral blood leukocytes from HIV-infected patients can cross an epithelial cell line barrier using transcytosis, the characteristic epithelial transcellular vesicular pathway. As the next step in the spread of infection, transcytosed HIV particles can productively infect mononuclear cells located at the basolateral side of the epithelial barrier. These observations suggest an alternative, rapid and efficient mechanism for transmission of HIV across an intact epithelial barrier.

Prevalence of cytomegalovirus infection in severe refractory ulcerative and Crohn's colitis

OBJECTIVES

Cytomegalovirus infection has been reported as a cause of refractory inflammatory bowel disease, but no data are available on its prevalence in severe colitis. The aim of this study was to evaluate the prevalence and outcome of cytomegalovirus infection in a consecutive series of patients with severe steroid refractory colitis admitted to our department from 1997 to 1999.

METHODS

Among 62 patients with severe colitis, 55 with ulcerative colitis and seven with Crohn's disease, 19 (30%) were resistant to intravenous steroids and bowel rest. In all of them, rectal biopsies were examined for cytomegalovirus (the flexible proctoscopy being performed without air insufflation and limited to the first 10 cm). Buffy coat preparation on leukocytes was also performed to detect systemic infection. If cytomegalovirus was not detected, cyclosporine was started.

RESULTS

In seven (five with ulcerative colitis and two with Crohn's disease) out of 19 (36%) patients with refractory disease, cytomegalovirus was diagnosed in the rectal specimens as well as by buffy coat preparation. Five patients went into remission after antiviral treatment (three with ganciclovir and two with foscarnet). One patient did not respond and was operated on. In one patient, cytomegalovirus was found in the surgical specimen.

CONCLUSIONS

Cytomegalovirus infection is a frequent cause of severe refractory colitis. Rectal biopsy should always be performed in severe steroid-resistant colitis.

Antigen crosspresentation by human plasmacytoid dendritic cells

Crosspresentation is a specialized function of myeloid dendritic cells (mDCs), allowing them to induce CD8+ T cell responses against exogenous antigens that are not directly produced in their cytotosol. Human plasmacytoid DCs (pDCs) are not considered so far as able to perform crosspresentation. We showed here that purified human pDCs crosspresented vaccinal lipopeptides and HIV-1 antigens from apoptotic cells to specific CD8+ T lymphocytes. Apoptotic debris were internalized by phagocytosis and the lipopeptide LPPol reached nonacidic endosomes. This crosspresentation was amplified upon influenza virus infection. Importantly, the efficiency of crosspresentation by pDCs was comparable to that of mDCs. This property of human pDCs needs to be taken into account to understand the pathogenesis of infectious, allergic, or autimmune diseases and to help achieve desired responses during vaccination by targeting specifically either type of DCs.

The interferon landscape along the respiratory tract impacts the severity of COVID-19

Severe coronavirus disease 2019 (COVID-19) is characterized by overproduction of immune mediators, but the role of interferons (IFNs) of the type I (IFN-I) or type III (IFN-III) families remains debated. We scrutinized the production of IFNs along the respiratory tract of COVID-19 patients and found that high levels of IFN-III, and to a lesser extent IFN-I, characterize the upper airways of patients with high viral burden but reduced disease risk or severity. Production of specific IFN-III, but not IFN-I, members denotes patients with a mild pathology and efficiently drives the transcription of genes that protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In contrast, compared to subjects with other infectious or noninfectious lung pathologies, IFNs are overrepresented in the lower airways of patients with severe COVID-19 that exhibit gene pathways associated with increased apoptosis and decreased proliferation. Our data demonstrate a dynamic production of IFNs in SARS-CoV-2-infected patients and show IFNs play opposing roles at distinct anatomical sites.

Foreign (M13) DNA ingested by mice reaches peripheral leukocytes, spleen, and liver via the intestinal wall mucosa and can be covalently linked to mouse DNA

Food-ingested foreign DNA is not completely degraded in the gastrointestinal tract of mice. Phage M13mp18 DNA as a test molecule devoid of homology to mouse DNA was pipette-fed to or added to the food supply of mice. The fate of this foreign DNA in the animals was followed by several methods. In 84 animals, fragments of M13mp18 DNA were detected in the contents of the small intestine, the cecum (until 18 h), the large intestine, or the feces. In 254 animals, M13mp18 DNA fragments of up to 976 bp were found in blood 2-8 h after feeding. In buffer-fed control animals, M13mp18 DNA could not be detected. M13mp18 DNA fragments were traced by PCR in peripheral leukocytes and located by fluorescent in situ hybridization in about 1 of 1000 white cells between 2 and 8 h, and in spleen or liver cells up to 24 h after feeding, but not later. M13mp18 DNA could be traced by fluorescent in situ hybridization in the columnar epithelial cells, in the leukocytes in Peyer's patches of the cecum wall, in liver cells, and in B cells, T cells, and macrophages from spleen. These findings suggest transport of foreign DNA through the intestinal wall and Peyer's patches to peripheral blood leukocytes and into several organs. Upon extended feeding, M13mp18 DNA could be recloned from total spleen DNA into a lambda vector. Among about 2.5 x 10(7) lambda plaques, one plaque was isolated that contained a 1299 nucleotide pair fragment (nt 4736-6034) of sequence-identified M13mp18 DNA. This fragment was covalently linked to an 80 nt DNA segment with 70% homology to the mouse IgE receptor gene. The DNA from another lambda plaque also contained mouse DNA, bacterial DNA, and rearranged lambda DNA. Two additional plaques contained M13mp18 DNA fragments of at least 641 (nt 2660-3300) or 794 (nt 4640-5433) nucleotide pairs. The medical and evolutionary implications of these observations may be considerable.

Asymptomatic primary cytomegalovirus infection: virologic and immunologic features

We followed 45 seronegative adolescents for acquisition of cytomegalovirus (CMV); 6 (5 female, 1 male) seroconverted after a median of 7.5 months. All were free of signs and symptoms. CMV was isolated from 32 (59.2%) of 54 urines, 2-80 weeks after infection; viruria was less frequent after 6 months. CMV was isolated from saliva of 3 subjects, vaginal swabs of 2 of 5, and 1 white blood cell (WBC) sample. CMV DNA was detected by polymerase chain reaction in WBCs and plasma from all subjects tested. The proportion of WBC samples with CMV DNAemia was 75%-80% within 16 weeks of infection, declining to 0%-25% after 48 weeks. The rate of plasma DNAemia was 25%-40% at 8-16 weeks, declining with time. IgG antibody to CMV, glycoprotein B (gB), and neutralizing antibody were present after 6-8 weeks. Lymphocyte proliferative responses to CMV and to gB were low, compared with those of controls. CMV shedding was of shorter duration than expected. Although antibody response was prompt and vigorous, CMV DNA could be detected in blood for months.

Cell cycle arrest by Vpr in HIV-1 virions and insensitivity to antiretroviral agents

Expression of human immunodeficiency virus-type 1 (HIV-1) Vpr after productive infection of T cells induces cell cycle arrest in the G2 phase of the cell cycle. In the absence of de novo expression, HIV-1 Vpr packaged into virions still induced cell cycle arrest. Naturally noninfectious virus or virus rendered defective for infection by reverse transcriptase or protease inhibitors were capable of inducing Vpr-mediated cell cycle arrest. These results suggest a model whereby both infectious and noninfectious virions in vivo, such as those surrounding follicular dendritic cells, participate in immune suppression.

Human cytomegalovirus in blood of immunocompetent persons during primary infection: prognostic implications for pregnancy

Human cytomegalovirus (HCMV) was investigated in peripheral blood leukocytes (PBL) of 52 immunocompetent patients (40 pregnant women) with primary HCMV infection by quantitative determination of pp65 antigenemia, viremia, and leukoDNAemia. pp65 antigenemia was detected in 12 (57.1%) of 21, 4 (25%) of 16, and 0 of 10 patients examined 1, 2, and 3 months after onset, respectively. Viremia was detected in 5 (26.3%) of 19 patients during the first month only. LeukoDNAemia was detected in 20 of 20, 17 (89.5%) of 19, and 9 (47.3%) of 19 patients tested 1, 2, and 3 months after onset, respectively. Four (26.6%) of 15 patients were still DNAemia-positive at 4-6 months, whereas none were positive at >6 months. HCMV was not detected in PBL of 20 HCMV-immune donors or of 9 seropositive subjects with recurrent infection. Virus levels were low by all assays and did not correlate with clinical course of infection, intrauterine transmission, or severity of outcome. Invasive procedures in the presence of maternal leukoDNAemia did not seem to interfere with vertical transmission of HCMV infection.

The clinical use of various blood compartments for cytomegalovirus (CMV) DNA quantitation in transplant recipients with CMV disease

BACKGROUND

The quantitation of cytomegalovirus (CMV) DNA is a cornerstone in the management of CMV disease in transplant recipients. However, a consensus as to what is the optimal blood compartment for the detection and quantitation of CMV DNA in peripheral blood is nonexistent.

METHODS

With an automated quantitative assay, we have simultaneously quantified the CMV DNA load in whole blood (WB), plasma (PL), peripheral blood leukocytes (PBL), and peripheral blood mononuclear cells (PBMC) in 319 samples from 17 transplant recipients with 19 episodes of CMV disease that were treated with 2 weeks of intravenous ganciclovir.

RESULTS

Higher levels of CMV DNA were observed in WB than PL (PL minus WB mean difference, 0.67 log; 95% confidence interval, -1.02 to -0.32; P=0.0009). This observation was most evident before treatment with intravenous ganciclovir (pretreatment geometric mean CMV DNA was 45,412 copies per ml of WB vs. 14,995 copies per ml of PL). In contrast, the CMV DNA levels between PBL and PBMC were highly comparable throughout the course of CMV disease and its treatment. Intravenous ganciclovir exerted a uniform effect on the four blood compartments with no statistically significant difference in the degree and rate of CMV DNA decline between WB and PL and between PBL and PBMC.

CONCLUSIONS

Although our study demonstrates the adequacy of all blood compartments for CMV DNA quantification, the higher sensitivity of WB and its yield of higher CMV DNA render it an optimal sample for monitoring CMV DNA load during CMV disease in immunocompromised patients.

Quantification of human cytomegalovirus DNA by real-time PCR

A quantitative real-time PCR assay was developed to measure human cytomegalovirus (HCMV) DNA load in peripheral blood leukocytes (PBLs). The HCMV DNA load in PBLs was normalized by means of the quantification of a cellular gene (albumin). The results of the real-time PCR assay correlated with those of the HCMV pp65-antigenemia assay (P < 0.0001).

Infection of a yellow baboon with simian immunodeficiency virus from African green monkeys: evidence for cross-species transmission in the wild

Many African primates are known to be naturally infected with simian immunodeficiency viruses (SIVs), but only a fraction of these viruses has been molecularly characterized. One primate species for which only serological evidence of SIV infection has been reported is the yellow baboon (Papio hamadryas cynocephalus). Two wild-living baboons with strong SIVAGM seroreactivity were previously identified in a Tanzanian national park where baboons and African green monkeys shared the same habitat (T. Kodama, D. P. Silva, M. D. Daniel, J. E. Phillips-Conroy, C. J. Jolly, J. Rogers, and R. C. Desrosiers, AIDS Res. Hum. Retroviruses 5:337-343, 1989). To determine the genetic identity of the viruses infecting these animals, we used PCR to examine SIV sequences directly in uncultured leukocyte DNA. Targeting two different, nonoverlapping genomic regions, we amplified and sequenced a 673-bp gag gene fragment and a 908-bp env gene fragment from one of the two baboons. Phylo-genetic analyses revealed that this baboon was infected with an SIVAGM strain of the vervet subtype. These results provide the first direct evidence for simian-to-simian cross-species transmission of SIV in the wild.

M11L: a novel mitochondria-localized protein of myxoma virus that blocks apoptosis of infected leukocytes

M11L, a novel 166-amino acid membrane-associated protein expressed by the poxvirus, myxoma virus, was previously found to modulate apoptosis after infection of rabbit leukocytes. Furthermore, infection of rabbits with an M11L knockout virus unexpectedly produced lesions with a profound proinflammatory phenotype. We show here that M11L is antiapoptotic when expressed independently of other viral proteins, and is directed specifically to mitochondria by a short COOH-terminal region that is necessary and sufficient for targeting. This targeting region consists of a hydrophobic domain flanked by basic amino acid residues, adjacent to a positively charged tail. M11L blocks staurosporine-induced apoptosis by preventing mitochondria from undergoing a permeability transition, and the mitochondrial localization of this protein is essential for this function. We show that M11L is specifically required to inhibit the apoptotic response of monocytes/macrophages during virus infection, as cells of this lineage undergo apoptosis when infected with the M11L knockout virus. As monocyte apoptosis is uniquely proinflammatory, we propose that this observation reconciles the paradoxical proapoptotic and proinflammatory phenotypes of the M11L knockout virus. We suggest that apoptosis of tissue macrophages represents an important antiviral defense, and that the inhibition of apoptosis by viral proteins can be directed in a cell-specific fashion.

Comparative quantitation of human cytomegalovirus DNA in blood leukocytes and plasma of transplant and AIDS patients

A new method for the quantitation of human cytomegalovirus (HCMV) DNA was used to determine the levels of viral DNA in parallel in 120 blood leukocyte (leukoDNAemia) and plasma (plasmaDNAemia) samples from 8 heart or heart-lung transplant patients and 17 AIDS patients with disseminated HCMV infection. PlasmaDNAemia was consistently associated with leukoDNAemia in both groups of patients. However, at least in the transplant patients, plasmaDNAemia was not necessarily associated with clinical symptoms, appearing later and disappearing earlier than leukoDNAemia during the course of infection. Quantitative mean levels of leukoDNAemia were mostly higher than those of plasmaDNAemia in both transplant and AIDS patients. However, in the absence of antiviral treatment, plasmaDNAemia levels were significantly higher in AIDS patients than in transplant recipients, whereas leukoDNAemia levels were not significantly different between the two groups of patients. A significant correlation was found between leukoDNAemia and plasmaDNAemia in AIDS patients, as well as in transplant recipients, although to a lesser degree. However, from a diagnostic standpoint, quantitative determination of plasmaDNAemia appears to represent a much less sensitive parameter than that of leukoDNAemia (or antigenemia) for monitoring HCMV infections and antiviral treatment.

Transmission of tick-borne pathogens between co-feeding ticks: Milan Labuda's enduring paradigm

During the 1990s, Milan Labuda's experimental results established a new paradigm for the study of tick-borne viruses that has since been strengthened by its demonstrated effectiveness in explaining the epidemiology of tick-borne encephalitis (TBE). This brief review summarizes the essential features of the transmission of tick-borne pathogens such as TBE virus. Leukocytes migrate between tick feeding sites, bearing infective virions and providing a transport route for the virus between co-feeding ticks independent of a systemic viraemia. Such tick-borne pathogens are thus transmitted from tick to tick via vertebrates; the ticks are the reservoirs as well as the vectors, while the vertebrate is the transient bridge. The aim is to bring the related but non-synonymous terms (co-feeding and non-systemic) to the attention of workers who use simple PCR screening to identify additional vertebrate reservoir hosts of vector-borne pathogens that are not in fact maintained in nature through systemic transmission.

Hepatitis C augments cognitive deficits associated with HIV infection and methamphetamine

OBJECTIVE

To examine the contribution of hepatitis C virus (HCV) infection to neurocognitive dysfunction in individuals with comorbid HIV infection or methamphetamine (METH) dependence.

METHODS

Neurocognitive functioning was examined in 430 study participants who were either normal controls or had HCV infection, HIV infection, history of METH dependence, or combinations of these factors as risks for cognitive deficits.

RESULTS

Rates of global and domain-specific neuropsychological (NP) impairment increased with the number of risk factors. HCV serostatus was a significant predictor of NP performance both globally and in the areas of learning, abstraction, and motor skills, with trends in speeded information processing and delayed recall. HCV serostatus did not predict scores in attention/working memory or verbal fluency.

CONCLUSION

Hepatitis C virus infection contributes to the neuropsychological deficits observed among HIV-infected and stimulant-dependent populations.

African swine fever virus infection of the bushpig (Potamochoerus porcus) and its significance in the epidemiology of the disease

Warthog (Phacochoerus aethiopicus), giant forest hog (Hylochoerus meinertzhageni) and bushpig (Potamochoerus porcus) are known to be susceptible to infection with African swine fever (ASF) virus. Little however, is known about the ecology of the disease in the bushpig. This study has shown that the bushpig remains viraemic for between 35 and 91 days following infection during which time it is able to infect the tick vector O. moubata. These ticks were able to transmit the disease to pigs. The virus persists in the lymphatic tissues for less than 34 weeks. Bushpigs infected with LIL 20/l virus but not VIC T90/l virus transmitted infection to in-contact pigs. Infected domestic pigs did not transmit the infection to in-contact bushpigs. ASF virus was able to replicate in in vitro cultures of bushpig leucocytes and endothelial cells. Recovered bushpigs could be reinfected with some strains of virus but not others. While it has been demonstrated that bushpigs remain carriers of ASFV following infection a complete understanding of their significance in the epidemiology of the disease awaits further investigations of their association with O. moubata.

Nodavirus increases the expression of Mx and inflammatory cytokines in fish brain

Nodavirus has become a serious pathogen for a wide range of cultured marine fish species. In the present work, the expression of genes related to immune and inflammatory responses of sea bream (Sparus aurata L.), considered as non susceptible species, was studied both in vitro and in vivo. No replication of the virus was observed in head kidney macrophages and blood leukocytes. Moreover, the enhancement of expression of several immune genes (tumor necrosis factor alpha (TNFalpha), interleukin-1-beta (IL-1beta), interferon-induced Mx protein) was not detected in both head kidney macrophages and blood leucocytes in response to an in vitro infection with nodavirus. However, in vivo, nodavirus was detected 1 day post-infection (p.i.) by a reverse transcription-polymerase chain reaction (RT-PCR) in blood, liver, head kidney and brain of experimentally infected sea bream, while its presence clearly decreased in blood after 3 days p.i. Also, a transitory increment of the expression of TNFalpha and IL-1beta was detected in the brain of intramuscular (i.m.) infected sea bream 3 days p.i. In head kidney, the over expression of TNFalpha was only observed 1 day p.i. The expression of Mx, an interferon induced gene, was increased in brain and head kidney of infected sea bream, reaching values of 1300-fold compared to controls in brain three days post-infection. For comparative purposes, we analyzed the expression of the same genes on a susceptible species, such as sea bass (Dicentrarchus labrax) and, although the same pattern of expression was observed both in brain and kidney, the magnitude was different mainly in the case of brain, the key organ of the infection, where higher expression of TNFalpha and lower expression of Mx compared with control was observed.

Interferon-alpha-induced endogenous superantigen. a model linking environment and autoimmunity

We earlier proposed that a human endogenous retroviral (HERV) superantigen (SAg) IDDMK(1,2)22 may cause type I diabetes by activating autoreactive T cells. Viral infections and induction of interferon-alpha (IFN-alpha) are tightly associated with the onset of autoimmunity. Here we establish a link between viral infections and IFN-alpha-regulated SAg expression of the polymorphic and defective HERV-K18 provirus. HERV-K18 has three alleles, IDDMK(1,2)22 and two full-length envelope genes, that all encode SAgs. Expression of HERV-K18 SAgs is inducible by IFN-alpha and this is sufficient to stimulate V beta 7 T cells to levels comparable to transfectants constitutively expressing HERV-K18 SAgs. Endogenous SAgs induced via IFN-alpha by viral infections is a novel mechanism through which environmental factors may cause disease in genetically susceptible individuals.

Myocarditis and inflammatory cardiomyopathy: microbiological and molecular biological aspects

Myocarditis is an inflammatory disease of the myocardium associated with cardiac dysfunction. The natural history of myocarditis is frequently characterised by the evolution in dilated cardiomyopathy. Due to its variable clinical manifestation from latent to very severe clinical forms, such as acute congestive heart failure and sudden death, its prevalence is still unknown and probably underestimated. In spite of the development of various diagnostic modalities, early and definite diagnosis of myocarditis still depends on the detection of inflammatory infiltrates in endomyocardial biopsy specimens according to the Dallas criteria. Routine application of immunohistochemistry, used for identification and characterisation of inflammatory cell populations, has now significantly increased the sensistivity of the diagnosis of inflammatory cardiomyopathy. Various molecular techniques, such as PCR, gene sequencing and real-time PCR, often applied on the same endomyocardial specimen, have become an essential part of the diagnostic armamentarium for rapid, specific and sensitive identification of infective agents. The correct application of molecular techniques will allow increasingly more information to be obtained: new epidemiology, new patient risk stratification and overall more appropriate medical treatment.

Herpesvirus infection of inflammatory cells in human periodontitis

Human cytomegalovirus (HCMV) and Epstein-Barr virus type 1 (EBV-1) are frequently detected in human periodontitis lesions. However, no information is available on the types of gingival cells infected by herpesviruses. The present study determined the presence of herpesviruses in polymorphonuclear neutrophils, monocytes, macrophages and T and B lymphocytes in biopsies of periodontitis lesions from 20 adults. A nested polymerase chain reaction method was employed to detect HCMV, EBV-1, EBV-2, human herpes virus-6 and herpes simplex virus (HSV) in periodontal tissue biopsy and in gingival cell fractions separated by immunomagnetic cell sorting. Tissue specimens from 18 (90%) and cell fractions from 14 (70%) patients demonstrated herpesviruses. Periodontitis-derived monocytes and macrophages revealed HCMV in cell fractions from 11 (55%) patients and HSV in cells from 1 (5%) patient. T lymphocytes harbored HCMV in cell fractions from 4 (20%) patients and HSV in cell fractions from 4 (20%) patients. B lymphocytes showed EBV-1 in cell fractions from 9 (45%) patients. Periodontal polymorphonuclear neutrophils demonstrated no herpesviruses. This study suggests that HCMV mainly infects periodontal monocytes, macrophages and less frequently T lymphocytes and that EBV-1 infects periodontal B lymphocytes. The possible etio-pathologic significance of periodontal herpesvirus infection is discussed.

Regulation of human immunodeficiency virus type 1 and cytokine gene expression in myeloid cells by NF-kappa B/Rel transcription factors

CD4+ macrophages in tissues such as lung, skin, and lymph nodes, promyelocytic cells in bone marrow, and peripheral blood monocytes serve as important targets and reservoirs for human immunodeficiency virus type 1 (HIV-1) replication. HIV-1-infected myeloid cells are often diminished in their ability to participate in chemotaxis, phagocytosis, and intracellular killing. HIV-1 infection of myeloid cells can lead to the expression of surface receptors associated with cellular activation and/or differentiation that increase the responsiveness of these cells to cytokines secreted by neighboring cells as well as to bacteria or other pathogens. Enhancement of HIV-1 replication is related in part to increased DNA-binding activity of cellular transcription factors such as NF-kappa B. NF-kappa B binds to the HIV-1 enhancer region of the long terminal repeat and contributes to the inducibility of HIV-1 gene expression in response to multiple activating agents. Phosphorylation and degradation of the cytoplasmic inhibitor I kappa B alpha are crucial regulatory events in the activation of NF-kappa B DNA-binding activity. Both N- and C-terminal residues of I kappa B alpha are required for inducer-mediated degradation. Chronic HIV-1 infection of myeloid cells leads to constitutive NF-kappa B DNA-binding activity and provides an intranuclear environment capable of perpetuating HIV-1 replication. Increased intracellular stores of latent NF-kappa B may also result in rapid inducibility of NF-kappa B-dependent cytokine gene expression. In response to secondary pathogenic infections or antigenic challenge, cytokine gene expression is rapidly induced, enhanced, and sustained over prolonged periods in HIV-1-infected myeloid cells compared with uninfected cells. Elevated levels of several inflammatory cytokines have been detected in the sera of HIV-1-infected individuals. Secretion of myeloid cell-derived cytokines may both increase virus production and contribute to AIDS-associated disorders.