Rhinovirus Infections and Associated Respiratory Morbidity in Infants: A Prospective Cohort Study.

BACKGROUND Risk factors promoting rhinovirus (RV) infections are inadequately described in healthy populations, especially infants. OBJECTIVES To determine the frequency of symptomatic and asymptomatic RV infections and identify possible risk factors from host and environment among otherwise healthy infants. METHODS In a prospective birth cohort, respiratory health was assessed in 41 term-born infants by weekly telephone interviews during the first year of life, and weekly nasal swabs were collected to determine RV prevalence. In a multilevel logistic regression model, associations between prevalence and respiratory symptoms during RV infections and host/environmental factors were determined. RESULTS 27% of nasal swabs in 41 infants tested positive for RVs. Risk factors for RV prevalence were autumn months (OR=1.71, p=0.01, 95% CI 1.13-2.61), outdoor temperatures between 5-10 °C (OR=2.33, p=0.001, 95% CI 1.41-3.86), older siblings (OR=2.60, p=0.001, 95% CI 1.50-4.51) and childcare attendance (OR=1.53, p=0.07, 95% CI 0.96-2.44). 51% of RV-positive samples were asymptomatic. Respiratory symptoms during RV infections were less likely during the first three months of life (OR=0.34, p=0.003, 95% CI 0.17-0.69) and in infants with atopic mothers (OR=0.44, p=0.008, 95% CI 0.24-0.80). Increased tidal volume (OR=1.67, p=0.03, 95% CI 1.04-2.68) and outdoor temperatures between 2-5 °C (OR=2.79, p=0.02, 95% CI 1.17-6.61) were associated with more symptoms. CONCLUSIONS RVs are highly prevalent during the first year of life, and most infections are asymptomatic. Frequency of RV infections is associated with environmental factors, while respiratory symptoms during RV infections are linked to host determinants like infant age, maternal atopy, or premorbid lung function.

Estimating the net contribution of interleukin-28B variation to spontaneous hepatitis C virus clearance

The identification of associations between interleukin-28B (IL-28B) variants and the spontaneous clearance of hepatitis C virus (HCV) raises the issues of causality and the net contribution of host genetics to the trait. To estimate more precisely the net effect of IL-28B genetic variation on HCV clearance, we optimized genotyping and compared the host contributions in multiple- and single-source cohorts to control for viral and demographic effects. The analysis included individuals with chronic or spontaneously cleared HCV infections from a multiple-source cohort (n = 389) and a single-source cohort (n = 71). We performed detailed genotyping in the coding region of IL-28B and searched for copy number variations to identify the genetic variant or haplotype carrying the strongest association with viral clearance. This analysis was used to compare the effects of IL-28B variation in the two cohorts. Haplotypes characterized by carriage of the major alleles at IL-28B single-nucleotide polymorphisms (SNPs) were highly overrepresented in individuals with spontaneous clearance versus those with chronic HCV infections (66.1% versus 38.6%, P = 6 × 10(-9) ). The odds ratios for clearance were 2.1 [95% confidence interval (CI) = 1.6-3.0] and 3.9 (95% CI = 1.5-10.2) in the multiple- and single-source cohorts, respectively. Protective haplotypes were in perfect linkage (r(2) = 1.0) with a nonsynonymous coding variant (rs8103142). Copy number variants were not detected. CONCLUSION: We identified IL-28B haplotypes highly predictive of spontaneous HCV clearance. The high linkage disequilibrium between IL-28B SNPs indicates that association studies need to be complemented by functional experiments to identify single causal variants. The point estimate for the genetic effect was higher in the single-source cohort, which was used to effectively control for viral diversity, sex, and coinfections and, therefore, offered a precise estimate of the net host genetic contribution.

Management of hepatitis C virus (HCV) infection in drug substitution programs

In Switzerland, intravenous drug use (IDU) accounts for 80% of newly acquired hepatitis C virus (HCV) infections. Early HCV treatment has the potential to interrupt the transmission chain and reduce morbidity/mortality due to decompensated liver cirrhosis and hepatocellular carcinoma. Nevertheless, patients in drug substitution programs are often insufficiently screened and treated.

Phylogenetic and virulence analysis of tick-borne encephalitis virus field isolates from Switzerland

Tick-borne encephalitis (TBE) is an endemic disease in Switzerland, with about 110-120 reported human cases each year. Endemic areas are found throughout the country. However, the viruses circulating in Switzerland have not been characterized so far. In this study, the complete envelope (E) protein sequences and phylogenetic classification of 72 TBE viruses found in Ixodes ricinus ticks sampled at 39 foci throughout Switzerland were analyzed. All isolates belonged to the European subtype and were highly related (mean pairwise sequence identity of 97.8% at the nucleotide and 99.6% at the amino acid level of the E protein). Sixty-four isolates were characterized in vitro with respect to their plaque phenotype. More than half (57.8%) of isolates produced a mixture of plaques of different sizes, reflecting a heterogeneous population of virus variants. Isolates consistently forming plaques of small size were associated with recently detected endemic foci with no or only sporadic reports of clinical cases. All of six virus isolates investigated in an in vivo mouse model were highly neurovirulent (100% mortality) but exhibited a relatively low level of neuroinvasiveness, with mouse survival rates ranging from 50% to 100%. Therefore, TBE viruses circulating in Switzerland belong to the European subtype and are closely related. In vitro and in vivo surrogates suggest a high proportion of isolates with a relatively low level of virulence, which is in agreement with a hypothesized high proportion of subclinical or mild TBE infections.

Molecular pathogenesis of infections caused by Moraxella catarrhalis in children

Moraxella catarrhalis (M. catarrhalis) is a human-restricted commensal of the normal bacterial flora in the upper respiratory tract of children, and - during the previous two decades - has been recognised as a true human pathogen. M. catarrhalis is the third most common pathogen causing acute otitis media in children, which is the most common reason to visit a paediatrician during childhood. Acute otitis media thus causes a high clinical and economical burden. With the introduction of the conjugate pneumococcal vaccines the microbiomic pattern in the nasopharyngeal flora of children has changed, and the frequency of isolation of M. catarrhalis has increased. Compared to adults, children are more often colonised with M. catarrhalis. Over the last three decades there has been a dramatic increase in the acquisition of β-lactam resistance in M. catarrhalis. Today 95-100% of clinically isolated M. catarrhalis produce β-lactamase. It is thus desirable to reduce the burden of M. catarrhalis disease by developing a vaccine. There are several potential vaccine antigen candidates in different stages of development, but none of them has entered clinical trials at the present time.

Rhinovirus infections in infancy and early childhood

Rhinovirus (RV) infections occur early and recurrently in life, imposing a significant burden of disease on infants and young children. They are the most frequent causative agents of both upper and lower respiratory tract infections in this age group and are associated with a broad variety of clinical outcomes, ranging from asymptomatic infections to severe respiratory disease requiring hospitalisation. In addition to their impact on short-term morbidity, RVs are also debated as important pathogens in the development of recurrent wheeze and/or asthma. Several studies in infants at high-risk for atopy and asthma and in hospitalised children have demonstrated that recurrent wheezing illnesses induced by RVs early in life are a risk factor for the development of asthma later in childhood. However, underlying mechanisms are poorly understood. The question whether RVs are directly involved in the development of childhood wheeze and asthma, or whether symptomatic RV infections only represent a proxy for infants prone to develop obstructive lung diseases, is still open. In this review we provide an overview on the role of RVs as important disease-causing agents from infancy to early childhood and discuss their contribution to the subsequent development of childhood wheeze and/or asthma.

[How the bovine viral diarrhea virus outwits the immune system]

The interaction of bovine viral diarrhea virus (BVD virus) with its host has several unique features, most notably the capacity to infect its host either transiently or persistently. The transient infection stimulates an antiviral immune reaction similar to that seen in other transient viral infections. In contrast, being associated with immunotolerance specific for the infecting BVD viral strain, the persistent infection differs fundamentally from other persistent infections like those caused by lentiviruses. Whereas the latter are characterized by complex viral evasion of the host's adaptive immune response by mechanisms such as antigenic drift and interference with presentation of T cell epitopes, BVD virus avoids the immune response altogether by inducing both humoral and cellular immune tolerance. This is made possible by invasion of the fetus at an early stage of development. In addition to adaptive immunity, BVD virus also manipulates key elements of the host's innate immune response. The non-cytopathic biotype of BVD virus, which is capable of persistently infecting its host, fails to induce type I interferon. In addition, persistently infected cells are resistant to the induction of apoptosis by double-stranded RNA and do not produce interferon when treated with this pathogen-associated molecular pattern (PAMP) that signals viral infection. Moreover, when treated with interferon, cells persistently infected with non-cytopathic BVD virus do not clear the virus. Surprisingly, however, despite this lack of effect on persistent infection, interferon readily induces an antiviral state in these cells, as shown by the protection against infection by unrelated viruses. Overall, BVD virus manipulates the host's interferon defense in a manner that optimises its chances of maintaining the persistent infection as well as decreasing the risks that heterologous viral infections may carry for the host. Thus, since not all potential host cells are infected in animals persistently infected with BVD virus, heterologous viruses replicating in cells uninfected with BVD virus will still trigger production of interferon. Interferon produced by such cells will curtail the replication of heterologous viruses only, be that in cells already infected with BVD virus, or in cells in which the heterologous virus may replicate alone. From an evolutionary viewpoint, this strategy clearly enhances the chances of transmission of BVD virus to new hosts, as it attenuates the negative effects that a global immunosuppression would have on the survival of persistently infected animals.

Hepatitis C virus and non-Hodgkin's lymphoma: Findings from the Swiss HIV Cohort Study

Infections with hepatitis C virus (HCV) and, possibly, hepatitis B virus (HBV) are associated with an increased risk of non-Hodgkin's lymphoma (NHL) in the general population, but little information is available on the relationship between hepatitis viruses and NHL among people with HIV (PHIV). We conducted a matched case-control study nested in the Swiss HIV Cohort Study (SHCS). Two hundred and ninety-eight NHL cases and 889 control subjects were matched by SHCS centre, gender, age group, CD4+ count at enrollment, and length of follow-up. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were computed using logistic regression to evaluate the association between NHL and seropositivity for antibodies against HCV (anti-HCV) and hepatitis B core antigen (anti-HBc), and for hepatitis B surface antigen (HBsAg). Anti-HCV was not associated with increased NHL risk overall (OR = 1.05; 95% CI: 0.63-1.75), or in different strata of CD4+ count, age or gender. Only among men having sex with men was an association with anti-HCV found (OR = 2.37; 95% CI: 1.03-5.43). No relationships between NHL risk and anti-HBc or HBsAg emerged. Coinfection with HIV and HCV or HBV did not increase NHL risk compared to HIV alone in the SHCS.

Imatinib mesylate selectively impairs expansion of memory cytotoxic T cells without affecting the control of primary viral infections

Imatinib mesylate (imatinib) is a potent inhibitor of defined tyrosine kinases (TKs) and is effective in the treatment of malignancies characterized by constitutive activation of these TKs such as chronic myeloid leukemia and gastrointestinal stromal tumors. TKs also play an important role in T-cell receptor (TCR) signal transduction. Inhibitory as well as stimulating effects of imatinib on T cells and dendritic cells have been described. Here, we analyzed the effects of imatinib treatment on antiviral immune responses in vivo. Primary cytotoxic T-cell (CTL) responses were not impaired in imatinib-treated mice after infection with lymphocytic choriomeningitis virus (LCMV) or after immunization with a tumor cell line expressing LCMV glycoprotein (LCMV-GP). Similarly, neutralizing antibody responses to vesicular stomatitis virus (VSV) were not affected. In contrast, secondary expansion of LCMV-specific memory CTLs was reduced in vitro and in vivo, resulting in impaired protection against reinfection. In addition, imatinib treatment delayed the onset of diabetes in a CTL-induced diabetes model. In summary, imatinib treatment in vivo selectively inhibits the expansion of antigen-experienced memory CTLs without affecting primary T- or B-cell responses. Therefore, imatinib may be efficacious in the suppression of CTL-mediated immunopathology in autoimmune diseases without the risk of acquiring viral infections.

Nitazoxanide, a broad-spectrum thiazolide anti-infective agent for the treatment of gastrointestinal infections

Colonisation of the gastrointestinal tract by anaerobic bacteria, protozoa, trematodes, cestodes and/or nematodes and other infectious pathogens, including viruses, represents a major cause of morbidity and mortality in Africa, South America and southeast Asia, as well as other parts of the world. Nitazoxanide is a member of the thiazolide class of drugs with a documented broad spectrum of activity against parasites and anaerobic bacteria. Moreover, the drug has recently been reported to have a profound activity against hepatitis C virus infection. In addition, nitazoxanide exhibits anti-inflammatory properties, which have prompted clinical investigations for its use in Crohn's disease. Studies with nitazoxanide derivatives have determined that there must be significantly different mechanisms of action acting on intracellular versus extracellular pathogens. An impressive number of clinical studies have shown that the drug has an excellent bioavailability in the gastrointestinal tract, is fast acting and highly effective against gastrointestinal bacteria, protozoa and helminthes. A recent Phase II study has demonstrated viral response (hepatitis C) to monotherapy, with a low toxicity and an excellent safety profile over 24 weeks of treatment. Pre-clinical studies have indicated that there is a potential for application of this drug against other diseases, not primarily affecting the liver or the gastrointestinal tract.

Chronic rhinoviral infection in lung transplant recipients

RATIONALE: Lung transplant recipients are particularly at risk of complications from rhinovirus, the most frequent respiratory virus circulating in the community. OBJECTIVES: To determine whether lung transplant recipients can be chronically infected by rhinovirus and the potential clinical impact. METHODS: We first identified an index case, in which rhinovirus was isolated repeatedly, and conducted detailed molecular analysis to determine whether this was related to a unique strain or to re-infection episodes. Transbronchial biopsies were used to assess the presence of rhinovirus in the lung parenchyma. The incidence of chronic rhinoviral infections and potential clinical impact was assessed prospectively in a cohort of 68 lung transplant recipients during 19 mo by screening of bronchoalveolar lavages. MEASUREMENTS AND MAIN RESULTS: We describe 3 lung transplant recipients with graft dysfunctions in whom rhinovirus was identified by reverse transcriptase-polymerase chain reaction in upper and lower respiratory specimens over a 12-mo period. In two cases, rhinovirus was repeatedly isolated in culture. The persistence of a unique strain in each case was confirmed by sequence analysis of the 5'NCR and VP1 gene. In the index case, rhinovirus was detected in the lower respiratory parenchyma. In the cohort of lung transplant recipients, rhinoviral infections were documented in bronchoalveolar lavage specimens of 10 recipients, and 2 presented with a persistent infection. CONCLUSIONS: Rhinoviral infection can be persistent in lung transplant recipients with graft dysfunction, and the virus can be detected in the lung parenchyma. Given the potential clinical impact, chronic rhinoviral infection needs to be considered in lung transplant recipients.

Vaccination with a T-cell-priming Gag peptide of caprine arthritis encephalitis virus enhances virus replication transiently in vivo

CD4+ T cells are involved in several immune response pathways used to control viral infections. In this study, a group of genetically defined goats was immunized with a synthetic peptide known to encompass an immunodominant helper T-cell epitope of caprine arthritis encephalitis virus (CAEV). Fifty-five days after challenge with the molecularly cloned CAEV strain CO, the vaccinated animals had a higher proviral load than the controls. The measurement of gamma interferon and interleukin-4 gene expression showed that these cytokines were reliable markers of an ongoing immune response but their balance did not account for more or less efficient control of CAEV replication. In contrast, granulocyte-macrophage colony-stimulating factor appeared to be a key cytokine that might support virus replication in the early phase of infection. The observation of a potential T-cell-mediated enhancement of virus replication supports other recent findings showing that lentivirus-specific T cells can be detrimental to the host, suggesting caution in designing vaccine candidates.

Worldwide occurrence of feline hemoplasma infections in wild felid species

While hemoplasma infections in domestic cats are well studied, almost no information is available on their occurrence in wild felids. The aims of the present study were to investigate wild felid species as possible reservoirs of feline hemoplasmas and the molecular characterization of the hemoplasma isolates. Blood samples from the following 257 wild felids were analyzed: 35 Iberian lynxes from Spain, 36 Eurasian lynxes from Switzerland, 31 European wildcats from France, 45 lions from Tanzania, and 110 Brazilian wild felids, including 12 wild felid species kept in zoos and one free-ranging ocelot. Using real-time PCR, feline hemoplasmas were detected in samples of the following species: Iberian lynx, Eurasian lynx, European wildcat, lion, puma, oncilla, Geoffroy's cat, margay, and ocelot. "Candidatus Mycoplasma haemominutum" was the most common feline hemoplasma in Iberian lynxes, Eurasian lynxes, Serengeti lions, and Brazilian wild felids, whereas "Candidatus Mycoplasma turicensis" was the most prevalent in European wildcats; hemoplasma coinfections were frequently observed. Hemoplasma infection was associated with species and free-ranging status of the felids in all animals and with feline leukemia virus provirus-positive status in European wildcats. Phylogenetic analyses of the 16S rRNA and the partial RNase P gene revealed that most hemoplasma isolates exhibit high sequence identities to domestic cat-derived isolates, although some isolates form different subclusters within the phylogenetic tree. In conclusion, 9 out of 15 wild felid species from three different continents were found to be infected with feline hemoplasmas. The effect of feline hemoplasma infections on wild felid populations needs to be further investigated.

Immunohistochemical diagnosis of persistent infection with Bovine Viral Diarrhea Virus (BVDV) on skin biopsies

Detection of persistent infection with BovineViral Diarrhea Virus (BVDV) is essential for both epidemiological and clinical reasons. In addition to the classical virological methods such as virus isolation in tissue culture, ELISA and RT-PCR, immunohistochemistry of skin biopsies has become a useful and reliable tool. Assuming that the presence of BVDV antigen in skin structures is restricted to persistent infection, this method could differentiate from transient infection. In order to answer this question, 6 calves were experimentally infected orally with a non-cytopathic genotype 1 BVDV strain belonging to the subtype k.The calves developed fever, mucopurulent nasal discharge, coughing and leucopenia with relative lymphopenia. Immunohistochemistry of skin biopsies taken daily up to day 13-post infection did not reveal any evidence of BVDV infection. BVDV was, however, isolated from blood samples on cell cultures. Anti-NS3-antibody-ELISA and serum neutralization tests showed that all six calves seroconverted. We conclude that in acute BVDV infections, with genotype 1 and the subtypes found in Switzerland (b, e, h and k) viral antigen is not found in epidermal structures of the skin. In contrast, persistently infected animals test positive for BVD viral antigen by immunohistochemistry of the skin.