Transient Infection Research Articles

High rates of Mycobacterium fortuitum isolation in respiratory samples from Iranian patients with suspected tuberculosis: is it clinically important?

Although Mycobacterium fortuitum (M. fortuitum) is not an organism rarely isolated from respiratory samples, its clinical importance is still not fully understood, which therefore prompted our current study. We evaluated respiratory samples from 6800 patients with suspected tuberculosis from May 2014 to May 2016, for the detection of M. fortuitum using phenotypic and genotyping methods.Results/Key findings. Of the 40 patients with M. fortuitum lung disease, 35 had two or more positive culture results. The mean age of these 35 patients was 50.7±18.4 years, and 20 (57.1 %) were men. Sputum (68.6 %), haemoptysis (51.4 %), cough (45.7 %) and gastroesophageal disease (22.9 %) were the major presenting symptoms. Cystic fibrosis, other bacterial lung diseases and lung cancer were the main underlying pulmonary diseases. Five patients (12.5 %) were human immunodeficiency virus (HIV) positive. The most common chest X-ray findings were reticulonodular opacities (53.3 %). Multivariate logistic regression analysis revealed that cigarette smoking history (OR 0.334, 95 % CI 0.125-0.843, P=0.048) and underlying lung disease (OR 0.393, 95 % CI 0.216-0.588, P=0.023) were significant predictors for positive M. fortuitum infection. These results demonstrated the high frequency of M. fortuitum in respiratory samples and that this bacterium causes transient infection or colonization in patients with underlying pulmonary conditions, such as cystic fibrosis and cigarette smoking-induced. Additionally, it appears that infection with M. fortuitum is particularly common and may be important in patients with HIV.

Giardia Infection of the Small Intestine Induces Chronic Colitis in Genetically Susceptible Hosts.

The lumen-dwelling protozoan Giardia is an important parasitic cause of diarrheal disease worldwide. Infection can persist over extended periods with minimal intestinal inflammation, suggesting that Giardia may attenuate host responses to ensure its survival, although clearance eventually occurs in most cases. IL-10 is an anti-inflammatory regulator critical for intestinal homeostasis and controlling host responses to bacterial exposure, yet its potential role in coordinating antiprotozoal host defense in the intestine is not known. In this study, we found that murine infection with the natural enteric pathogen Giardia muris induced a transient IL-10 response after 2-4 wk at the primary site of infection in the upper small intestine, but parasite colonization and eradication were not affected by the absence of the cytokine in gene-targeted mice. However, IL-10 was critical for controlling infection-associated immunological sequelae in the colon because severe and persistent diarrhea and colitis were observed in IL-10-deficient mice within 1-2 wk postinfection but not in uninfected littermate controls. Inflammation was characterized by epithelial hyperplasia, neutrophil and macrophage expansion, and Th1 induction and could be prevented by blockade of IL-12/IL-23 p40 but not depletion of CD11c+ dendritic cells. Furthermore, the intestinal microbiota underwent characteristic shifts in composition and was required for disease because antibiotics and loss of TLR signaling in MyD88-deficient mice protected against colitis. Together, our data suggest that transient infection by a luminal and seemingly noninflammatory pathogen can trigger sustained colitis in genetically susceptible hosts, which has broader implications for understanding postinfectious syndromes and other chronic intestinal inflammatory conditions.

The myriad challenges of respiratory fungal infection in cystic fibrosis.

Fungal infection in cystic fibrosis (CF) is a recognized challenge, with many areas requiring further investigation. Consensus definitions exist for allergic bronchopulmonary aspergillus in CF, but the full scope of clinically relevant non-allergic fungal disease in CF-asymptomatic colonization, transient or chronic infection localized to endobronchial mucus plugs or airway tissue, and invasive disease-is yet to be clearly defined. Recent advances in mycological culture and non-culture identification have expanded the list of both potential pathogens and community commensals in the lower respiratory tract. Here we aim to outline the current understanding of fungal presence in the CF respiratory tract, risk factors for acquiring fungi, host-pathogen interactions that influence the role of fungi from bystander to pathogen, advances in the diagnostic approaches to isolating and identifying fungi in CF respiratory samples, challenges of classifying clinical phenotypes of CF patients with fungi, and current treatment approaches. Development and validation of biomarkers characteristic of different fungal clinical phenotypes, and controlled trials of antifungal agents in well-characterized target populations, remain central challenges to surmount and goals to be achieved.

Abstract CT080: Clinical and immunologic results of a multi-center, randomized, double blind, phase II trial using poly-gamma-glutamic acid (γ-PGA) for women with cervical intraepithelial neoplasia 1 (CIN 1) and correlation of PD-1/PD-L1 tumor expression

Abstract Introduction : The poly-gamma-glutamic acid (γ-PGA) is a safe and edible polypeptide that is naturally synthesized by Bacillus subtilis 1 and has long been taken up as an ingredient of fermented soybean foods. The γ-PGA as a signaling regulator of Toll-like receptor 4 (TLR4), has been shown to enhance natural killer (NK) cell activity and inhibit tumors. Although CIN-1 typically represents transient infection, about 10% of CIN-1 is found to progress to CIN-3, and HPV infection persists and leads to high grade cervical dysplasia in some women with CIN-1. The aim of this study was to investigate the efficacy and safety of γ-PGA and impact γ-PGA on the immune system including PD-1 / PD-L1 in patients with CIN 1. Material & Methods : We conducted a multi-center, randomized, double blind, placebo control, parallel designed, phase 2b study. Participants were randomly assigned to one of two groups: half received oral solution containing 1500 mg of γ-PGA; half received a placebo. Each participants took one dose every 24 hours for 4 weeks. Colposcopy with biopsy was assessed at the time of screening and 12 weeks. Blood samples were drawn at the initial treatment and at the 4th, 8th, 12th weeks after treatment. The primary endpoint of the study was histologic regression rate between screening and 12th weeks. The secondary endpoint were cytologic response rate, HPV clearance, change of immune responses and PD-1/PD-L1 expression. Result From April 2013 to December 2015, 254 patients were screened and a total of 200 patients participated in the study. Of these, Of 101 women in γ-PGA group, 42 (42.4%) women experienced histologic regression, whereas 26 (27.1%) in the control group experienced histologic regression, showing statistically significant differences (p=0.018). In the γ- PGA group, HPV clearance was found in 37 (43.5%) of the 85 high-risk HPV infected patients, showing a meaningful difference compared to the control group showing HPV clearance of 20 (26.7%) out of 75 (p=0.026). However, there was no significant difference between the two groups in terms of cytologic regression rate and type specific clearance of HPV. The immunologic factors including NK cell activity, CD8 cell count and PD-1/PD-L1 expression, which are thought to be related to the therapeutic mechanism of γ- PGA, showed no significant difference between the two groups. Conclusion : The γ-PGA enhance histologic regression in CIN-1 patients and showed the possibility of non-invasive medical treatment. In addition, γ-PGA has shown its potential as a treatment for high-grade CIN or cancer in the future as it has been shown to be effective against high-risk HPV infection. Citation Format: Hyun-Woong Cho, Yung-Taek Ouh, Jin Hwa Hong, Jae Kwan Lee, Jae-Won Jeon, Moon-Hee Sung. Clinical and immunologic results of a multi-center, randomized, double blind, phase II trial using poly-gamma-glutamic acid (γ-PGA) for women with cervical intraepithelial neoplasia 1 (CIN 1) and correlation of PD-1/PD-L1 tumor expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT080.

Viral Load in the Natural History of Human Papillomavirus Infection Among Men in Rural China: A Population-based Prospective Study.

High-risk human papillomavirus (HR-HPV) load is predictive of HR-HPV persistence and subsequent carcinogenesis in women. However, in men, data on genital HPV load and its effect on the natural history of HPV infection are limited. The subjects included 1532 men aged 25-65 years with up to 7 biannual visits for evaluation of genital HPV load in rural China during 2009-2013 who were positive for ≥1 of the 18 selected HPV types (including 10 HR-HPV types) detected by general primer-mediated polymerase chain reaction (PCR) and sequencing. Type-specific HPV load was quantified with real-time PCR and dichotomized based on median values. Men with multiple lifetime sex partners were more likely to have higher overall levels of HR-HPV load across visits (adjusted odds ratio, 2.42; 95% confidence interval [CI], 1.12-5.24; 2 partners vs 0-1 partner). Higher levels of HR-HPV load at the time of the first HPV diagnosis conferred an increased probability of the subject remaining type-specific HPV-positive up to 12 months and an increased probability of persistent/intermittent infection (virus detected repeatedly with or without a period of intercurrent negativity) versus transient infections (single-time positive). Higher overall HR-HPV levels were predictive of reduced HR-HPV clearance rates (adjusted hazard ratio, 0.47; 95% CI, .27-.83). Having multiple lifetime sex partners is associated with increased male genital HR-HPV load. Higher HR-HPV load predicts persistence of HR-HPV in men from rural China.

18 - Identification of productive and transforming anal intraepithelial neoplasia using immunohistochemical markers p16INK4a and HPV E4

Background Immunohistochemical (IHC) biomarkers enable standardised, reproducible grading of anal intraepithelial neoplasia (AIN) based on progression of HPV infection from transient productive infection to complete neoplastic transformation. We investigated the expression of IHC biomarker HPV E4, a marker of productive HPV infection, in different grades of AIN caused by low-risk (lr) and high-risk (hr) HPV infection. Methods A reference grading of AIN was established using expert, consensus, subjective HE diagnoses supported by p16 expression for 183 anal biopsies: normal squamous epithelium 37, AIN1 67, AIN2 43, AIN3 36. Causative HPV genotype of the worst lesion was identified using laser capture microdissection and SPF10-PCR. Results Most AIN1 lesions were caused by lrHPV (72%) whereas most AIN2 (84%) and AIN3 (92%) was caused by hrHPV. None of the normal biopsies showed E4 positivity and 49% (33/67) of AIN1, 56% (24/43) of AIN2 and 3% (1/36) of AIN3 showed E4 positivity. While the large majority of E4 positive AIN1 (26/33) and AIN2 (16/24) lesions showed extensive positivity, the E4 positive AIN3 lesion showed only focal, superficial E4 positivity. HPV E4 positivity was seen in lesions caused by lr and hr HPV. Conclusions Our results show that when using HPV E4 in addition to p16, productive infections among both low-grade and high-grade AIN can be identified. Studies that further explore progression and regression in transforming (E4 negative) and productive (E4 positive) high-grade AIN, are necessary.

In vitro studies identify a low replication phenotype for hepatitis B virus genotype H generally associated with occult HBV and less severe liver disease

Hepatitis B virus (HBV) exists as 9 major genotypes and multiple subtypes, many of which exhibit differences in pathogenicity and treatment response. Genotype H identified in Central America is associated with low incidence of liver disease and HCC, but higher incidence of occult HBV (low level HBV DNA positivity, HBsAg negative). The replication phenotype of genotype H associated with less severe forms of liver disease is unknown. We hypothesized that the reduced pathogenesis associated with this genotype may be due to by lower rates of viral replication and/or secretion compared to other characterised strains. We used transient transfection and infection cell culture models to characterise the replication phenotype, compared to our D3 reference strain. Genotype H exhibited reduced viral replication and altered envelope protein expression compared to genotype D, with functional studies showing that low replication was in part likely due to sequence differences in the major transcriptional regulatory region.

G-108 Molecular etiology of cervical cancer, HPV and gene methylation

Most cervical cancers are caused by persistent infections with one of a dozen carcinogenic human papillomaviruses (HPV). The cancer risk differs by HPV genotype, with HPV16 and HPV18 accounting for over 70% of all cervical cancers. E6 and E7, are potent oncoproteins that inhibit apoptosis by disabling p53 and activate the cell cycle by disrupting the pRB pathway. In addition, the viral oncogenes cause major chromosomal instability already at precancerous stages and may induce integration of the viral genome into the host cells. Despite these strong oncogenic features of HPV, only a small subset of HPV infections ever progress to precancer or cancer. Recently, the important role of host and viral methylation in the molecular etiology of cervical cancer has been recognized. We recently conducted a discovery effort that yielded a set of host gene methylation markers that showed promising performance to detect cervical precancer. Similarly, we recently showed that regions of the HPV genome of 11 carcinogenic types are highly methylated in women with CIN3 compared to women with transient infections, suggesting that methylation is a general phenomenon in the transition from infection to precancer. Methylation patterns were found to be similar between closely related HPV genotypes. These findings may improve our understanding of the molecular basis for viral persistence and increase our ability to identify women who are more likely to progress to cervical cancer. Measuring host or HPV DNA methylation could serve as a specific marker for cervical precancer in cervical cancer screening.

The Human Respiratory Microbiome: Implications and Impact.

Once considered a sterile site below the larynx, the tracheobronchial tree and parenchyma of the lungs are now known to harbor a rich diversity of microbial species including bacteria, viruses, fungi, and archaea. Many of these organisms, particularly the viruses which comprise the human respiratory virome, have not been identified, so their true role is unknown. It seems logical to conclude that a "healthy" respiratory microbiome exists which may be modified in disease states and perhaps by therapies such as antibiotics, antifungals, and antiviral treatments. It is likely that there is a critical relationship or equilibrium between components of the microbiome until such time as perturbations occur which lead to a state of dysbiosis or an "unhealthy" microbiome. The act of lung transplantation provides an extreme change to an individual's respiratory microbiome as, in effect, the donor respiratory microbiome is transplanted into the recipient. The mandatory ex-vivo period of the donor lungs appears to be associated with blooms of resident viral species in particular. Subsequently, allograft injury, rejection, and immune suppressive therapy all combine to create periods of dysbiosis which when combined with transient infections such as community acquired respiratory viruses may facilitate the development of chronic allograft dysfunction in predisposed individuals. As our understanding of the respiratory microbiome is rapidly expanding, based on the use of new-generation sequencing tools in particular, it is to be hoped that insights gained into the subtle relationship between the microbiome and the lung allograft will facilitate improved outcomes by directing novel therapeutic endeavors.

The Colibactin Genotoxin Generates DNA Interstrand Cross-Links in Infected Cells.

ABSTRACTColibactins are hybrid polyketide-nonribosomal peptides produced by Escherichia coli, Klebsiella pneumoniae, and other Enterobacteriaceae harboring the pks genomic island. These genotoxic metabolites are produced by pks-encoded peptide-polyketide synthases as inactive prodrugs called precolibactins, which are then converted to colibactins by deacylation for DNA-damaging effects. Colibactins are bona fide virulence factors and are suspected of promoting colorectal carcinogenesis when produced by intestinal E. coli. Natural active colibactins have not been isolated, and how they induce DNA damage in the eukaryotic host cell is poorly characterized. Here, we show that DNA strands are cross-linked covalently when exposed to enterobacteria producing colibactins. DNA cross-linking is abrogated in a clbP mutant unable to deacetylate precolibactins or by adding the colibactin self-resistance protein ClbS, confirming the involvement of the mature forms of colibactins. A similar DNA-damaging mechanism is observed in cellulo, where interstrand cross-links are detected in the genomic DNA of cultured human cells exposed to colibactin-producing bacteria. The intoxicated cells exhibit replication stress, activation of ataxia-telangiectasia and Rad3-related kinase (ATR), and recruitment of the DNA cross-link repair Fanconi anemia protein D2 (FANCD2) protein. In contrast, inhibition of ATR or knockdown of FANCD2 reduces the survival of cells exposed to colibactin-producing bacteria. These findings demonstrate that DNA interstrand cross-linking is the critical mechanism of colibactin-induced DNA damage in infected cells.

Evaluation of bovine viral diarrhea virus transmission potential to naïve calves by direct and indirect exposure routes

Bovine viral diarrhea viruses (BVDV) can cause both acute and persistent infections in cattle. Exposure to BVDV persistently infected (PI) animals results in transmission of the virus to a naïve animal which causes a transient acute infection. While it is known that direct exposure to PI animals is a highly efficient means of transmission, less information is available regarding the potential for transmission from acutely infected either by direct or indirect exposure to naïve animals. Therefore, the objective of this study was to evaluate the potential for spread of the virus from calves acutely infected, with typical virulence field viruses know to have minimal shedding and viremia, to naïve contact animals either by direct or indirect exposure. To accomplish this objective, two BVDV isolates belonging to two species of BVDV, type 1 and type 2, were used to inoculate calves. Subsequently on day 2 post-infection, naïve calves were exposed to inoculated calves, either directly or indirectly, over a period of two weeks. All calves were evaluated for the presence of virus in blood samples and nasal swabs, pyrexia, lymphopenia and seroconversion. BVDV was isolated from inoculated calves but not from any of the direct and indirect contact animals or from control calves. Similarly, pyrexia and lymphopenia were observed in the inoculated calves, but not in contact and control calves. Only the inoculated calves seroconverted by day 38 of the study indicating that no transmission had occurred to the naïve contact calves. This data would suggest that there may be an infectious dose needed for transmission of virus for typical virulent isolates.

Control of Bovine Viral Diarrhea.

Bovine viral diarrhea (BVD) is one of the most important infectious diseases of cattle with respect to animal health and economic impact. Its stealthy nature, prolonged transient infections, and the presence of persistently infected (PI) animals as efficient reservoirs were responsible for its ubiquitous presence in cattle populations worldwide. Whereas it was initially thought that the infection was impossible to control, effective systematic control strategies have emerged over the last 25 years. The common denominators of all successful control programs were systematic control, removal of PI animals, movement controls for infected herds, strict biosecurity, and surveillance. Scandinavian countries, Austria, and Switzerland successfully implemented these control programs without using vaccination. Vaccination as an optional and additional control tool was used by e.g., Germany, Belgium, Ireland, and Scotland. The economic benefits of BVD control programs had been assessed in different studies.

Bovine viral diarrhea virus infections in pigs: why is this situation important for Brazilian herds?

ABSTRACT: Swine can be infected by the bovine viral diarrhea virus (BVDV) under natural conditions. For this reason, further information and divulgation are needed regarding the pathogenicity of this virus in swine. This infection is practically unknown in the realm of pig farming, and, as it shares some similarities with the classical swine fever virus (CSFV), its diagnosis becomes a challenge for official sanitary programs. Studies have shown the absence of clinical signs in piglets and reproductive problems in sows due to BVDV infections. There is little research on the prevalence, risk factors, preventive measures and control of BVDV in pigs around the world. And in Brazil, the data is practically non-existent. At the time of diagnosis, comparing the most efficient laboratory tests such as virus neutralization, ELISA, RT-PCR, and immunofluorescence so as to minimize the risk of cross serological reactions when dealing with a persistent or transient infection, can be an important tool. Moreover, the practical implications for CSFV eradication programs are a main reason for the development of further research against this infection. Therefore, this paper aims to review various aspects of BVDV infection in pigs, and how this information can be important for Brazilian herds.

Identification of genes required for Mycobacterium abscessus growth in vivo with a prominent role of the ESX-4 locus

Mycobacterium abscessus, a rapidly growing mycobacterium (RGM) and an opportunistic human pathogen, is responsible for a wide spectrum of clinical manifestations ranging from pulmonary to skin and soft tissue infections. This intracellular organism can resist the bactericidal defense mechanisms of amoebae and macrophages, an ability that has not been observed in other RGM. M. abscessus can up-regulate several virulence factors during transient infection of amoebae, thereby becoming more virulent in subsequent respiratory infections in mice. Here, we sought to identify the M. abscessus genes required for replication within amoebae. To this end, we constructed and screened a transposon (Tn) insertion library of an M. abscessus subspecies massiliense clinical isolate for attenuated clones. This approach identified five genes within the ESX-4 locus, which in M. abscessus encodes an ESX-4 type VII secretion system that exceptionally also includes the ESX conserved EccE component. To confirm the screening results and to get further insight into the contribution of ESX-4 to M. abscessus growth and survival in amoebae and macrophages, we generated a deletion mutant of eccB4 that encodes a core structural element of ESX-4. This mutant was less efficient at blocking phagosomal acidification than its parental strain. Importantly, and in contrast to the wild-type strain, it also failed to damage phagosomes and showed reduced signs of phagosome-to-cytosol contact, as demonstrated by a combination of cellular and immunological assays. This study attributes an unexpected and genuine biological role to the underexplored mycobacterial ESX-4 system and its substrates.

Molecular detection and characterization of transient bovine viral diarrhea virus (BVDV) infections in cattle commingled with ten BVDV persistently infected cattle.

Fifty-three cattle of unknown serologic status that were not persistently infected (PI) with bovine viral diarrhea virus (BVDV) were commingled with 10 cattle that were PI with different strains of BVDV, and were monitored for an extended commingle period using a reverse-transcription real-time PCR (RT-rtPCR) BVDV assay on various sample types. Transient infections with BVDV were also assessed by virus isolation, virus neutralization (VN) assays, and direct buffy coat 5'-UTR sequencing. Infections were demonstrated in all cattle by RT-rtPCR; however, the detection rate was dependent on the type of sample. Buffy coat samples demonstrated a significantly greater number of positive results ( p ≤ 0.05) than either serum or nasal swab samples. Presence of elevated BVDV VN titers at the onset inversely correlated with the number of test days positive that an individual would be identified by RT-rtPCR from buffy coat samples, and directly correlated with the average Ct values accumulated over all RT-rtPCR test days from buffy coat samples. Both single and mixed genotype/subgenotype/strain infections were detected in individual cattle by direct sample 5'-UTR sequencing. A BVDV-2a strain from a PI animal was found to be the predominant strain infecting 64% of all non-PI cattle; BVDV-1b strains originating from 3 PI cattle were never detected in non-PI cattle. Although direct sample 5'-UTR sequencing was capable of demonstrating mixed BVDV infections, identifying all strains suspected was not always efficient or possible.

Natural history of Mycobacterium fortuitum pulmonary infection presenting with migratory infiltrates: a case report with microbiological analysis

BackgroundPresence of Mycobacterium fortuitum in respiratory tracts usually indicates mere colonization or transient infection, whereas true pulmonary infection occurs in patients with gastroesophageal disease. However, little is known about the diagnostic indications for true M. fortuitum pulmonary infection and the natural history of the disease.Case presentationA 59-year-old man was referred to our hospital for treatment against M. fortuitum pulmonary infection. Fifteen years before the referral, he underwent total gastrectomy, after which he experienced esophageal reflux symptoms. After the referral, the patient was closely monitored without antimicrobial therapy because of mild symptoms and no pathological evidence of M. fortuitum pulmonary infection. During the observation, chest imaging showed migratory infiltrates. Two years after the referral, his lung biopsy specimen revealed foamy macrophages and multinucleated giant cells, indicating lipoid pneumonia. However, he was continually monitored without any treatment because there was no evidence of nontuberculous mycobacterial infection. Four years after the referral, he developed refractory pneumonia despite receiving adequate antibiotic therapy. After confirmation of granulomatous lesions, multiple antimicrobial therapy for M. fortuitum resulted in a remarkable improvement with no exacerbation for over 5 years. Random amplified polymorphic DNA polymerase chain reaction analysis revealed identical M. fortuitum strains in seven isolates from six sputum and one intestinal fluid specimens obtained during the course of the disease.ConclusionsWe have described a patient with M. fortuitum pulmonary infection who presented with migratory infiltrates. The pathological evidence and microbiological analysis suggested that M. fortuitum pulmonary infection was associated with lipoid pneumonia and chronic exposure to gastrointestinal fluid. Therefore, physicians should carefully monitor patients with M. fortuitum detected from lower respiratory tract specimens and consider antimicrobial therapy for M. fortuitum infection when the patient does not respond to adequate antibiotic therapy against common pneumonia pathogens.

Virome Analysis Reveals No Association of Head and Neck Vascular Anomalies with an Active Viral Infection.

Vascular anomalies encompass different vascular malformations [arteriovenous (AVM), lymphatic (LM), venous lymphatic (VLM), venous (VM)] and vascular tumors such as hemangiomas (HA). The pathogenesis of vascular anomalies is still poorly understood. Viral infection was speculated as a possible underlying cause. A total of 13 human vascular anomalies and three human skin control tissues were used for viral analysis. RNA derived from AVM (n=4) and normal skin control (n=3) tissues was evaluated by RNA sequencing. The Virome Capture Sequencing Platform for Vertebrate Viruses (VirCapSeq-VERT) was deployed on 10 tissues with vascular anomalies (2×AVM, 1×HA, 1×LM, 2×VLM, 4×VM). RNA sequencing did not show any correlation of AVM with viral infection. By deploying VirCapSeq-VERT, no consistent viral association was seen in the tested tissues. The analysis does not point to the presence of an active viral infection in vascular anomalies. However, transient earlier viral infections, e.g. during pregnancy, cannot be excluded with this approach.

Detection of human papillomavirus DNA in formalin-fixed, paraffin-embedded squamous papillomas of the oral cavity.

BackgroundSquamous papillomas are exophytic proliferations of surface oral epithelium. Human papillomavirus (HPV) infection is widely accepted as the etiology of squamous papillomas however the virus cannot be detected in a significant percentage of lesions.Material and MethodsUsing polymerase chain reaction (PCR), we tested 35 formalin-fixed paraffin-embedded (FFPE) squamous papillomas for the presence of HPV DNA.ResultsSix papillomas (17%) tested positive for HPV DNA; four contained HPV-6 and two contained HPV-11. Given that β–globin DNA was only identified in half of the samples, DNA degradation appears to have significantly impacted the results.ConclusionsThe results likely represent an underestimation of the true number of HPV-positive specimens in our study. Potential explanations for HPV-negative squamous papillomas include transient HPV infection, failure of the experiment to detect HPV if present, or the possibility that some lesions may not result from HPV infection. Key words:HPV, PCR, FFPE, papilloma, oral.

How do Viruses Cause Different Diseases? "From Transient Infection to Chronic Disease"

How do Viruses Cause Different Diseases? "From Transient Infection to Chronic Disease"

Genomic and Transcriptomic Analysis of Escherichia coli Strains Associated with Persistent and Transient Bovine Mastitis and the Role of Colanic Acid.

Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. It is most often transient in nature, causing an infection that lasts 2 to 3 days. However, E. coli has been shown to cause a persistent infection in a minority of cases. Mechanisms that allow for a persistent E. coli infection are not fully understood. The goal of this work was to determine differences between E. coli strains originally isolated from dairy cattle with transient and persistent mastitis. Using RNA sequencing, we show gene expression differences in nearly 200 genes when bacteria from the two clinical phenotypes are compared. We sequenced the genomes of the E. coli strains and report genes unique to the two phenotypes. Differences in the wca operon, which encodes colanic acid, were identified by DNA as well as RNA sequencing and differentiated the two phenotypes. Previous work demonstrated that E. coli strains that cause persistent infections were more motile than those that cause transient infections. Deletion of genes in the wca operon from a persistent-infection strain resulted in a reduction of motility as measured in swimming and swarming assays. Furthermore, colanic acid has been shown to protect bacteria from complement-mediated killing. We show that transient-infection E. coli strains were more sensitive to complement-mediated killing. The deletion of genes from the wca operon caused a persistent-infection E. coli strain to become sensitive to complement-mediated killing. This work identifies important differences between E. coli strains that cause persistent and transient mammary infections in dairy cattle.