Opportunistic pathogens frequently cause volatile infections in hosts with compromised immune systems or a disrupted normal microbiota. The commensalism of diverse microorganisms contributes to colonization resistance, which prevents the expansion of opportunistic pathogens. Following microbiota disruption, pathogens promptly adapt to altered niches and obtain growth advantages. Nevertheless, whether and how resident bacteria modulate the growth dynamics of invasive pathogens and the eventual outcome of such infections are still unclear. Here, we utilized birds as a model animal and observed a resident bacterium exacerbating the invasion of Avibacterium paragallinarum (previously Haemophilus paragallinarum) in the respiratory tract. We first found that negligibly abundant Staphylococcus chromogenes, rather than Staphylococcus aureus, played a dominant role in Av. paragallinarum-associated infectious coryza in poultry based on epidemic investigations and in vitro analyses. Furthermore, we determined that S. chromogenes not only directly provides the necessary nutrition factor nicotinamide adenine dinucleotide (NAD+) but also accelerates its biosynthesis and release from host cells to promote the survival and growth of Av. paragallinarum. Last, we successfully intervened in Av. paragallinarum-associated infections in animal models using antibiotics that specifically target S. chromogenes. Our findings show that opportunistic pathogens can hijack commensal bacteria to initiate infection and expansion and suggest a new paradigm to ameliorate opportunistic infections by modulating the dynamics of resident bacteria.

The compound genotype KIR3DS1/HLA-B Bw4-80I, which presumably favors natural killer cell activation, has been implicated in protection against HIV disease. We show that this genotype confers dual protection over the course of HIV disease; early direct containment of HIV viral load, and late specific defense against opportunistic infections, but not AIDS-related malignancies. The double protection of KIR3DS1/Bw4-80I in an etiologically complex disease such as AIDS, along with the disease specificity of its effects is conceptually novel and underscores the intricacy of host immunogenetics against HIV/AIDS.

The rise in nosocomial infections caused by multidrug-resistant pathogens is a major public health concern. Patients taking immunosuppressants or chemotherapeutics are naturally more susceptible to infections. Thus, strategies for protecting immunodeficient individuals from infections are of great importance. Here, we investigate the effectiveness of a biomimetic nanotoxoid vaccine in defending animals with immunodeficiency against Pseudomonas aeruginosa. The nanotoxoids use a macrophage membrane coating to sequester and safely present bacterial virulence factors that would otherwise be too toxic to administer. Vaccination with the nanoformulation results in rapid and long-lasting immunity, protecting against lethal infections despite severe immunodeficiency. The nanovaccine can be administered through multiple routes and is effective in both pneumonia and septicemia models of infection. Mechanistically, protection is mediated by neutrophils and pathogen-specific antibodies. Overall, nanotoxoid vaccination is an attractive strategy to protect vulnerable patients and could help to mitigate the threat posed by antibiotic-resistant superbugs.

Hematological malignancies disturb the blood, lymph nodes, and bone marrow. Taking medications for treating opportunistic infections (OIs) in these individuals may enhance the risk of medication interaction as well as adverse drug reactions.

HIV-infected individuals with severe immunodeficiency are at risk of opportunistic infection (OI). Tuberculosis (TB) may occur without substantial immune suppression suggesting an early and sustained adverse impact of HIV on Mycobacterium tuberculosis (MTB)-specific cell mediated immunity (CMI). This prospective observational cohort study aimed to observe differences in OI-specific and MTB-specific CMI that might underlie this. Using polychromatic flow cytometry, we compared CD4+ responses to MTB, cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Candida albicans in individuals with and without HIV infection. MTB-specific CD4+ T-cells were more polyfunctional than virus specific (CMV/EBV) CD4+ T-cells which predominantly secreted IFN-gamma (IFN-γ) only. There was a reduced frequency of IFN-γ and IL-2 (IL-2)-dual-MTB-specific cells in HIV-infected individuals, which was not apparent for the other pathogens. MTB-specific cells were less differentiated especially compared with CMV-specific cells. CD127 expression was relatively less frequent on MTB-specific cells in HIV co-infection. MTB-specific CD4+ T-cells PD-1 expression was infrequent in contrast to EBV-specific CD4+ T-cells. The variation in the inherent quality of these CD4+ T-cell responses and impact of HIV co-infection may contribute to the timing of co-infectious diseases in HIV infection.

Rapidly fatal cases of invasive fungal infections due to a fungus later identified as Saprochaete clavata were reported in France in May 2012. The objectives of this study were to determine the clonal relatedness of the isolates and to investigate possible sources of contamination. A nationwide alert was launched to collect cases. Molecular identification methods, whole-genome sequencing (WGS), and clone-specific genotyping were used to analyze recent and historical isolates, and a case-case study was performed. Isolates from thirty cases (26 fungemias, 22 associated deaths at day 30) were collected between September 2011 and October 2012. Eighteen cases occurred within 8 weeks (outbreak) in 10 health care facilities, suggesting a common source of contamination, with potential secondary cases. Phylogenetic analysis identified one clade (clade A), which accounted for 16/18 outbreak cases. Results of microbiological investigations of environmental, drug, or food sources were negative. Analysis of exposures pointed to a medical device used for storage and infusion of blood products, but no fungal contamination was detected in the unused devices. Molecular identification of isolates from previous studies demonstrated that S. clavata can be found in dairy products and has already been involved in monocentric outbreaks in hematology wards. The possibility that S. clavata may transmit through contaminated medical devices or can be associated with dairy products as seen in previous European outbreaks is highly relevant for the management of future outbreaks due to this newly recognized pathogen. This report also underlines further the potential of WGS for investigation of outbreaks due to uncommon fungal pathogens.

Apolipoprotein L1 (APOL1), an innate immune factor against African trypanosoma brucei, inhibits HIV-1 in vitro. The impact of APOL1 G1-G2 variants on HIV-1-associated opportunistic infections (OIs) is unknown. Here, we report findings from a metaanalysis of four HIV/AIDS prospective cohorts (ALIVE, LSOCA, MACS, and WIHS) including 2066 African American participants. Using a global test combining all four cohorts, carriage of two APOL1 variant alleles is associated with a 50% reduction in odds of OI (combined OR 0.50, 95% CI 0.33-0.76). Subgroup analysis of OI etiological categories (viral, parasitic, fungal and Mycobacterial) suggests the possibility of specific protection from fungal infections (OR 0.54. 95% CI 0.32-0.93; PBonferroni corrected = 0.08). We observe an association of APOL1 variant alleles with host protection against OI in HIV-positive individuals. The study suggests a broader role of APOL1 variant alleles in innate immunity in vivo.

Orosomucoid (ORM, composed of two isoforms, ORM1 and ORM2) has been described as an inducer of M2 macrophages, which are cells that decrease host antibacterial innate immunities. However, it is unknown which phenotypes of M2 macrophages are induced by ORM. In this study, healthy donor monocytes stimulated with ORM (ORM-monocytes) were characterized phenotypically and biologically. CCL1 (a biomarker of M2b macrophages) and IL-10 were detected in monocyte cultures supplemented with ORM1; however, CCL17 (a biomarker of M2a macrophages) and CXCL13 (a biomarker of M2c macrophages) were not produced in these cultures. All of these soluble factors were not detected in the culture fluids of monocytes stimulated with ORM2. Monocytes stimulated with ORM1 were characterized as CD64(-)CD209(-)CD163(+)CCL1(+) cells. MRSA and Enterococcus faecalis infections were accelerated in chimeras (NOD/scid IL-2Rγ(null) mice reconstituted with white blood cells) after inoculation with monocytes stimulated with ORM1 or treatment with ORM1; however, the infections were greatly mitigated in both chimeras inoculated with ORM1-stimulated monocytes and treated with ORM1, after an additional treatment with an inhibitor of M2b macrophages (CCL1 antisense ODN). These results indicate that ORM1 stimulates quiescent monocytes to polarize to M2b monocytes. The regulation of M2b macrophages may be beneficial in controlling opportunistic infections in patients with a large amount of plasma ORM1.

Oropharyngeal candidiasis (OPC) is an opportunistic fungal infection caused by Candida albicans. OPC is frequent in HIV/AIDS, implicating adaptive immunity. Mice are naive to Candida, yet IL-17 is induced within 24 h of infection, and susceptibility is strongly dependent on IL-17R signaling. We sought to identify the source of IL-17 during the early innate response to candidiasis. We show that innate responses to Candida require an intact TCR, as SCID, IL-7Rα(-/-), and Rag1(-/-) mice were susceptible to OPC, and blockade of TCR signaling by cyclosporine induced susceptibility. Using fate-tracking IL-17 reporter mice, we found that IL-17 is produced within 1-2 d by tongue-resident populations of γδ T cells and CD3(+)CD4(+)CD44(hi)TCRβ(+)CCR6(+) natural Th17 (nTh17) cells, but not by TCR-deficient innate lymphoid cells (ILCs) or NK cells. These cells function redundantly, as TCR-β(-/-) and TCR-δ(-/-) mice were both resistant to OPC. Whereas γδ T cells were previously shown to produce IL-17 during dermal candidiasis and are known to mediate host defense at mucosal surfaces, nTh17 cells are poorly understood. The oral nTh17 population expanded rapidly after OPC, exhibited high TCR-β clonal diversity, and was absent in Rag1(-/-), IL-7Rα(-/-), and germ-free mice. These findings indicate that nTh17 and γδ T cells, but not ILCs, are key mucosal sentinels that control oral pathogens.

Histoplasmosis and cryptococcosis are important public health problems in people living with HIV (PLHIV) in Central America. Conventional laboratory tests, such as culture and microscopy, are not optimal; however, antigen (Ag) tests are rapid, highly sensitive, and specific for diagnosis of fungal opportunistic infections (OI). The aim of this study was to describe the results of a laboratory-based surveillance system for histoplasmosis and cryptococcosis.

: The HIV/acquired immunodeficiency syndrome (AIDS) pandemic has affected the health status of the population in many countries. Early symptomatic HIV infection includes persistent generalized lymphadenopathy (PGL), which can be associated with opportunistic infections, e.g., toxoplasmosis and Cytomegalovirus (CMV) infection. This study followed the occurrence of PGL, toxoplasmosis, and Cytomegalovirus infection in 32 HIV-positive patients and analyzed the clinical signs of disease in relation to the number of CD4 T lymphocytes. In monitored patients, the average number of CD4 T lymphocytes was 940.8 ± 396.7/µL of blood. Severe immunodeficiency was recorded in four persons, who also suffered from colitis and/or retinitis and pneumonitis. The number of CD4 T cells in patients with PGL was significantly lower than that in patients without lymphadenopathy. In 6 (18.8%) IgM and 11 (34.4%) IgG Toxoplasma gondii seropositive patients, the number of CD4 T lymphocytes was significantly lower than that in seronegative patients. The presence of IgM and IgG antibodies to Cytomegalovirus was recorded in all examined patients, and CMV infection clinically manifested in five persons. The occurrence of PGL, the higher viral load, and seropositivity to T. gondii were significantly related to decline in the CD4 T lymphocyte number. The clinical course of the diseases was influenced by the status of the patient's immunodeficiency and suggests ongoing immunosuppression and possible reactivation of both infections in all patients.

Vedolizumab (ENTYVIO) is a humanized α4β7 integrin antagonist approved for the treatment of inflammatory bowel disease, which selectively blocks gut-specific lymphocyte trafficking. We evaluated the risk of opportunistic infections of interest in patients treated with vedolizumab.

Opportunistic bacterial and fungal infections are the major cause of morbidity and mortality among immune suppressed HIV-positive patients. The main objective of this study was to determine bacterial and fungal organisms causing respiratory infections and their susceptibility to commonly prescribed antimicrobials among HIV patients attending a tertiary infectious disease hospital in Kathmandu.

To derive a list of opportunistic infections (OI) through the analysis of the juvenile idiopathic arthritis (JIA) patients in the Pharmachild registry by an independent Safety Adjudication Committee (SAC).

As immune-modulating therapy has become the standard of care for idiopathic inflammatory joint diseases (IJD), we investigated whether this has changed the rates for hospitalization with opportunistic infections (OI).

Botryosphaeriaceae are an important fungal family that cause woody plant diseases worldwide. Recent studies have established a correlation between environmental factors and disease expression; however, less is known about factors that trigger these diseases. The current study reports on the 43.3 Mb de novo genome of Lasiodiplodia theobromae and five other genomes of Botryosphaeriaceae pathogens. Botryosphaeriaceous genomes showed an expansion of gene families associated with cell wall degradation, nutrient uptake, secondary metabolism and membrane transport, which contribute to adaptations for wood degradation. Transcriptome analysis revealed that genes involved in carbohydrate catabolism, pectin, starch and sucrose metabolism, and pentose and glucuronate interconversion pathways were induced during infection. Furthermore, genes in carbohydrate-binding modules, lysine motif domain and the glycosyl hydrolase gene families were induced by high temperature. Among these genes, overexpression of two selected putative lignocellulase genes led to increased virulence in the transformants. These results demonstrate the importance of high temperatures in opportunistic infections. This study also presents a set of Botryosphaeriaceae-specific effectors responsible for the identification of virulence-related pathogen-associated molecular patterns and demonstrates their active participation in suppressing hypersensitive responses. Together, these findings significantly expand our understanding of the determinants of pathogenicity or virulence in Botryosphaeriaceae and provide new insights for developing management strategies against them.

Opportunistic infections in the central nervous system (CNS) of people with HIV/AIDS (PLWHA) remain significant contributors to morbidity and mortality, especially in resource-limited scenarios. Diagnosing these infections can be challenging, as brain imaging is non-specific and expensive. Therefore, molecular analysis of cerebrospinal fluid (CSF) may offer a more accurate and affordable method for diagnosing pathogens.

Infections are a major cause of mortality after allogeneic haemopoietic stem cell transplantation (alloHSCT), and immune recovery is necessary for prevention. Novel transplant procedures have changed the epidemiology of infections but contemporary data on functional immune recovery are limited. In this pilot study, we aimed to measure immune recovery in the current era of alloHSCT.

Background and Objectives: Rheumatoid Arthritis (RA) is an auto-immune disease in which the body mistakenly considers some parts of its own system as pathogens and attacks them. Prevalence is approximately 0.75% in India. About 40% of the diseased become work disabled within 5 years from the onset of symptoms. The objective of this paper is to assess the sign/symptoms, joints' involvement, difficulties in daily activities and screening accuracy of serology tests of clinically suspected RA patients. Material and Methods: A cross-sectional cohort study design was conducted on two hundred ninety clinically suspected subjects who were referred by different OPDs of hospitals for screening. The profiles of study subjects were carried through a semi-structured, pre-tested schedule method. About 2 mL of blood samples were collected in a plain vial from each patient and tested for diagnostic tests RF, CRP and AntiCCP by using RF-Latex, CRP Latex and ELISA method, respectively, by the laboratory persons. Results: Joint pain shows to be a leading problem in RA as compared to other signs and symptoms. The majority of the study subjects suffer from knee problems (62%). Approximately equal numbers of RA-positive cases were screened by RF and AntiCCP tests. The CRP test screened about one-third of cases. CRP+ AntiCCP, RF+ AntiCCP and RF + CRP all have good sensitivity, and RF+ AntiCCP + CRP has a very high sensitivity for diagnosing RA. Conclusions: This study found that a substantiation of a major proportion of clinically suspected RA patients were suffering from knee pain. Predication of AntiCCP increased the possibility for the diagnosis of RA. However, RF was also moderately related to the diagnosis of RA, and the combination of both tests was more valuable.

Neutralizing anti-interferon (IFN)-γ autoantibodies are linked to opportunistic infections (OIs). To explore the association between anti-IFN-γ autoantibodies and OIs in patients with adult-onset Still's disease (AOSD), we aimed to examine the ability of these autoantibodies to blockade signal transducer and activator of transcription (STAT1)-phosphorylation and chemokines production.