IFN-γ enhances protective efficacy against Nocardia seriolae infection in largemouth bass (Micropterus salmoides).

Introduction: Nocardia seriolae adversely impacts a diverse range of fish species, exhibiting significant pathogenic characteristics that substantially impede the progress of aquaculture. N. seriolae infects in fish has a long incubation period, and clinical symptoms are not obvious in the early stages. There is presently no viable and eco-friendly approach to combat the spread of the disease. According to reports, N. seriolae primarily targets macrophages in tissues after infecting fish and can proliferate massively, leading to the death of fish. Interferon-gamma (IFN-γ) is a crucial molecule that regulates macrophage activation, but little is known about its role in the N. seriolae prevention. Methods: IFN-γ was first defined as largemouth bass (Micropterus salmoides, MsIFN-γ), which has a highly conserved IFN-γ characteristic sequence through homology analysis. The recombinant proteins (rMsIFN-γ) were obtained in Escherichia coli (E. coli) strain BL21 (DE3). The inflammatory response-inducing ability of rMsIFN-γ was assessed in vitro using monocytes/macrophages. Meanwhile, the protective effect of MsIFN-γ in vivo was evaluated by N. seriolae infection largemouth bass model. Results: In the inflammatory response of the monocytes/macrophages activated by rMsIFN-γ, various cytokines were significantly increased. Interestingly, interleukin 1ß (IL-1ß) and tumor necrosis factor alpha (TNF-a) increased by 183- and 12-fold, respectively, after rMsIFN-γ stimulation. rMsIFN-γ improved survival by 42.1% compared with the control. The bacterial load in the liver, spleen and head kidney significantly decreased. rMsIFN-γ was also shown to better induce increased expression of IL-1ß, TNF-α, hepcidin-1(Hep-1), major histocompatibility complex I (MHCI), and MHC II in head kidney, spleen and liver. The histopathological examination demonstrated the transformation of granuloma status from an early necrotic foci to fibrosis in the infection period. Unexpectedly, the development of granulomas was successfully slowed in the rMsIFN-γ group. Discussion: This work paves the way for further research into IFN-γ of largemouth bass and identifies a potential therapeutic target for the prevention of N. seriolae.

An Integrated in silico and in vivo study of nucleic acid vaccine against Nocardia seriolae infection in orange-spotted grouper Epinephelus coioides.

Nocardiosis in aquatic animals caused by Nocardia seriolae is a frequently occurring serious infection that has recently spread to many countries. In this study, DNA vaccines containing potential bacterial antigens predicted using the reverse vaccinology approach were developed and evaluated in orange-spotted groupers. In silico analysis indicated that proteins including cholesterol oxidase, ld-transpeptidase, and glycosyl hydroxylase have high immunogenicity and are potential vaccine candidates. In vitro assays revealed the mature and biological configurations of these proteins. Importantly, when compared to a control PBS injection, N. seriolae DNA-based vaccines showed significantly higher expression of IL1ß, IL17, and IFNγ at 1 or 2 days, in line with higher serum antibody production and expression of other cellular immune-related genes, such as MHCI, CD4, and CD8, at 7 days post-immunization. Remarkably, enhanced immune responses and strong protective efficacy against a highly virulent strain of N. seriolae were recorded in DNA vaccine-cholesterol oxidase (pcD::Cho) injected fish, with a relative survival rate of 73.3%. Our results demonstrate that the reverse vaccinology approach is a valid strategy for screening vaccine candidates and pcD::Cho is a promising candidate that can boost both innate and adaptive immune responses and confer considerable protection against N. seriolae infection.

Risk factors and prophylaxis for nocardiosis in solid organ transplant recipients: A nested case-control study.

BACKGROUND: Nocardia is an opportunistic pathogen that primarily affects immunocompromised individuals, including solid organ transplant (SOT) recipients. Up to 2.65% of SOT recipients develop nocardiosis; however, few studies have examined risk factors and prophylaxis for nocardiosis. METHODS: We performed a multicenter, matched nested case-control study of adult SOT recipients with culture-confirmed nocardiosis from 2000 through 2020. Controls were matched up to 2:1 by sex, first transplanted organ, year of transplant, transplant center, and adequate post-transplant follow-up. Multivariable conditional logistic regression was performed to analyze associations with nocardiosis. Cox proportional hazards regression compared 12-month mortality between infection and uninfected patients. RESULTS: One hundred and twenty-three SOT recipients were matched to 245 uninfected controls. Elevated calcineurin inhibitor level, acute rejection, cytomegalovirus infection, lymphopenia, higher prednisone dose, and older age were significantly associated with nocardiosis while trimethoprim-sulfamethoxazole prophylaxis was protective (odds ratio [OR] .34; 95% confidence interval [CI] .13-.84). The effect of prophylaxis was similar, though not always statistically significant, in sensitivity analyses that only included prophylaxis dosed more than twice-per-week (OR .30; 95% CI .11-.80) or restricted to years 2015-2020 (OR .33, 95% CI .09-1.21). Nocardiosis was associated with increased 12-month mortality (hazard ratio 5.47; 95% confidence interval 2.42-12.35). CONCLUSIONS: Multiple measures of immunosuppression and lack of trimethoprim-sulfamethoxazole prophylaxis were associated with nocardiosis in SOT recipients. Effectiveness of prophylaxis may be related to trimethoprim-sulfamethoxazole dose or frequency. Trimethoprim-sulfamethoxazole should be preferentially utilized over alternative agents in SOT recipients with augmented immunosuppression or signs of heightened immunocompromise.

Construction of an alanine dehydrogenase gene deletion strain for vaccine development against Nocardia seriolae in hybrid snakehead (Channa maculata ♀ × Channa argus ♂).

Nocardia seriolae is the main pathogen of fish nocardiosis. In our previous study, alanine dehydrogenase was identified as a potential virulence factor of N. seriolae. On the basis of this fact, the alanine dehydrogenase gene of N. seriolae (NsAld) was knocked out to establish the strain ΔNsAld for vaccine development against fish nocardiosis in this study. The LD50 of strain ΔNsAld was 3.90 × 105 CFU/fish, higher than that of wild strain (5.28 × 104 CFU/fish) significantly (p < 0.05). When the strain ΔNsAld was used as a live vaccine to immunize hybrid snakehead (Channa maculata ♀ × Channa argus ♂) at 2.47 × 105 CFU/fish by intraperitoneal injection, the non-specific immune indexes (LZM, CAT, AKP, ACP and SOD activities), specific antibody (IgM) titers and several immune-related genes (CD4, CD8α, IL-1ß, MHCIα, MHCIIα and TNFα) were up-regulated in different tissues, indicating that this vaccine could induce humoral and cell-mediated immune responses. Furthermore, the relative percentage survival (RPS) of ΔNsAld vaccine was calculated as 76.48% after wild N. seriolae challenge. All these results suggest that the strain ΔNsAld could be a potential candidate for live vaccine development to control fish nocardiosis in aquaculture.

Risk Factors and Outcomes of Nocardiosis in Hematopoietic Stem Cell Transplantation Recipients.

Nocardiosis occurs in up to 1.7% of hematopoietic stem cell transplantation (HSCT) recipients. Risk factors for its development and subsequent outcomes have been incompletely studied. The present study evaluated risk factors for nocardiosis in HSCT recipients and an association with 12-month mortality following Nocardia infection. We performed a nested case-control study of HSCT recipients at 3 transplantation centers between 2011 and 2021. Allogeneic HSCT recipients were matched 1:4 to controls based on age, sex, date of transplantation, and transplantation site. Because of theorized differences in the risk for nocardiosis between allogeneic HSCT recipients and autologous HSCT recipients and a low number of infected autologous HSCT recipients, only allogeneic HSCT recipients were matched to controls. Associations with nocardiosis in the allogeneic group were assessed by multivariable conditional logistic regression. Outcomes of all HSCT recipients with nocardiosis included 12-month mortality and post-treatment recurrence. Twenty-seven HSCT recipients were diagnosed with nocardiosis, including 20 allogeneic HSCT recipients and 7 autologous HSCT recipients. Twenty (74.1%) had localized pulmonary infection, 4 (14.8%) had disseminated infection, and 3 (11.1%) had localized skin infection. The allogeneic recipients were diagnosed at a median of 12.2 months after transplantation, compared with 41 months for the autologous recipients. All autologous HSCT recipients had alternative reasons for ongoing immunosuppression at diagnosis, most frequently therapy for relapsed hematologic disease. No infected patients were receiving trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis. In multivariable analysis of 20 allogeneic patients and 80 matched controls, graft-versus-host disease (GVHD) requiring current immunosuppression and lack of prophylaxis were associated with nocardiosis. Nocardiosis was significantly associated with subsequent mortality, with a 12-month mortality rate of 29.6%; however, no patients who completed treatment experienced Nocardia recurrence. OUR DATA INDICATE THAT: intensified immunosuppression following allogeneic HSCT, such as treatment for GVHD, is associated with the development of nocardiosis. Nocardiosis occurs more distantly from transplantation in autologous recipients, possibly driven by therapy for relapsed hematologic disease. No patients receiving TMP-SMX prophylaxis developed nocardiosis. Nocardia infection is associated with high mortality, and further strategies for prevention and treatment are needed.

Induction of attenuated Nocardia seriolae and their use as live vaccine trials against fish nocardiosis.

Nocardia seriolae, a Gram-positive facultative intercellular pathogen, has been identified as the causative agent of fish nocardiosis, causing substantial mortality and morbidity of a wide range of fish species. Looking into that fact, the effective vaccine against this pathogen is urgently needed to control the significant losses in aquaculture practices. In order to induct attenuated strains for developing the potential live vaccines, the mutagenic N. seriolae strain S-250 and U-20 were obtained from wild-type strain ZJ0503 through continuous passaging and ultraviolet (UV) irradiation, respectively. Additionally, the biological characteristic, virulence, stability, mediating immune response and supplying protective efficacy to hybrid snakehead of the S-250 and U-20 strains were determined in the present study. The results showed that U-20 strain displayed dramatic changes in morphological characteristic and significant decreased in the virulence to hybrid snakehead, while that of S-250 strain had no obvious different in comparison to ZJ0503 strain. When hybrid snakehead were intraperitoneally injected with ZJ0503, S-250 and U-20 strains at their respective sub-clinical dosage, the non-specific immunity parameters (serum LYZ, POD, ACP, AKP and SOD activities), specific antibody (IgM) titers production and immune-related genes (CC1, CC2, IL-1ß, IL-8, TNFα, IFNγ, MHCIα, MHCIIα, CD4, CD8α, TCRα and TCRß) expression were up-regulated, indicating that they were able to trigger humoral and cell-mediated immune responses. Furthermore, the protective efficacy in hybrid snakehead after vaccination with ZJ0503, S-250 and U-20 strains, in terms of relative percentage survival (RPS), were 28.85%, 56.89% and 89.65% respectively. Taken together, two attenuated N. seriolae strains S-250 and U-20 were obtained successfully and they could elicit strong immune response and supply protective efficacy to hybrid snakehead against N. seriolae, which suggested that these two attenuated strains were the potential candidates for live vaccine development to control fish nocardiosis in aquaculture.

Recurrent nocardiosis in solid organ transplant recipients: An evaluation of secondary prophylaxis.

BACKGROUND: Immunocompromised individuals are at risk for Nocardia infection, with a recurrence rate of approximately 5%. Solid organ transplant (SOT) recipients often receive secondary prophylaxis due to their requirement of lifelong immunosuppression. However, data supporting this practice is sparse. We sought to evaluate Nocardia recurrence in SOT recipients, specifically evaluating secondary prophylaxis. METHODS: We conducted a retrospective cohort study of SOT recipients diagnosed with nocardiosis from 2000 through 2020. We included adult SOT recipients who completed their course of Nocardia therapy and had at least 6 months of posttherapy follow-up. The primary outcome was Nocardia recurrence, which included relapse and reinfection. RESULTS: One hundred two patients met inclusion criteria. Sixty-six (64.7%) were male and mean age was 58.6 ± 11.7 years. Most common SOT types were kidney (46.1%), heart (18.6%), kidney-pancreas (11.8%), and lung (10.8%). Most common sites of infection were lung (85.3%), skin (17.6%), and brain (14.7%). Secondary prophylaxis was utilized in 53 (52.0%) patients. Trimethoprim-sulfamethoxazole (TMP-SMX) single-strength daily was the most common prophylaxis agent and dose. Five patients (4.9%) experienced Nocardia recurrence, three of which were receiving secondary prophylaxis at time of recurrence. Two recurrences were with the same Nocardia species. Factors associated with recurrence were lung transplantation (p = .011), chronic lung disease (p = .032), and treatment ≤120 days (p = .006). Time from treatment completion to recurrence ranged from 107 to 875 days. CONCLUSIONS: Nocardia recurrence in SOT recipients is an uncommon event. TMP-SMX secondary prophylaxis is incompletely protective and recurrence may be dependent upon other factors. Further study of secondary prophylaxis is warranted.

Nocardiosis in Immunocompromised Patients on Alternative Pneumocystis Prophylaxis.

Prophylactic trimethoprim/sulfamethoxazole (TMP/SMX) prevents Pneumocystis jirovecii pneumonia and nocardiosis in immunocompromised patients but sometimes is avoided because of purported allergies or side effects. Of 25 immunocompromised patients receiving alternative prophylaxis in whom nocardiosis developed, 16 subsequently tolerated TMP/SMX treatment. Clinicians should consider TMP/SMX allergy evaluation and rechallenging to assess patient tolerance.

Recombinant resuscitation-promoting factor protein of Nocardia seriolae, a promissing vaccine candidate for largemouth bass (Micropterus salmoides).

Nocardia seriolae is an important pathogenic bacterium that causes nocardiosis in various fish species and leads to economic losses in the fish industry. To develop an effective subunit vaccine against nocardial infection, the truncated resuscitation-promoting factor (tRPF) of N. seriolae was selected and recombinantly produced using the Escherichia coli expression system. Western blotting results indicated that the recombinant protein could be strongly recognised by largemouth bass anti-N. seriolae antibodies. The protective efficacy of tRPF recombinant protein was assessed in combination with the commercial adjuvant Montanide™ ISA 763 A VG. The results showed that emulsified tRPF + ISA significantly induced high serum antibody response and serum lysozyme activity in the vaccinated fish. Quantitative reverse transcription polymerase chain reaction analysis indicated that tRPF + ISA could notably enhance the expression of immune-related genes in both the head kidney and spleen of the vaccinated fish. Finally, vaccinated largemouth bass displayed higher immuno-protection with a relative percent survival of 69.23% compared to the control groups. Taken together, the combination of tRPF + ISA is an ideal vaccine candidate against N. seriolae infection.

Nocardia prophylaxis, treatment, and outcomes of infection in lung transplant recipients: A matched case-control study.

BACKGROUND: Lung transplant recipients are at heightened risk for nocardiosis compared to other solid organ transplant recipients, with incidence rates as high as 9% and up to 30% associated mortality. No controlled studies assessing risk factors for nocardiosis in this high-risk population have been reported. METHODS: Patients undergoing lung transplantation at a single center between 2012 and 2018 and diagnosed with nocardiosis post-transplant were matched 1:2 to uninfected control subjects on the basis of age, transplant date, and sex. RESULTS: The incidence of nocardiosis in this lung transplant population was 3.4% (20/586), occurring a median of 9.4 months (range 4.4-55.2) post-transplant. In multivariable analysis, consistent use of trimethoprim/sulfamethoxazole (TMP/SMX) in the 12 weeks prior to diagnosis was independently associated with protection against nocardiosis (OR 0.038; 95% CI 0.01-0.29; P = .002). Augmented immunosuppression in the 6 months prior to diagnosis was independently associated with the development of nocardiosis (OR 9.94; 95% CI 1.62- 61.00; P = .013). Six case patients (30%) had disseminated disease; all-cause 6-month mortality was 25%. The most common species was Nocardia farcinica (7/17 isolates), which was associated with dissemination and mortality. The most active antibiotics were TMP/SMX (100%), linezolid (100%), and amikacin (76%). Imipenem was only active against 4/17 isolates (24% susceptibility), with two isolates becoming non-susceptible later in therapy. CONCLUSIONS: Trimethoprim/sulfamethoxazole prophylaxis was shown to be protective against nocardiosis in lung transplant recipients, while augmented immunosuppression conferred increased risk. Institutional epidemiologic data are needed to best guide empiric therapy for Nocardia, as historical in vitro data may not predict local susceptibilities.

Immunogenicity and efficacy of two DNA vaccines encoding antigenic PspA and TerD against Nocardia seriolae in hybrid snakehead.

Fish nocardiosis is a widespread chronic granulomatous disease in aquatic environment, which was particularly caused by Nocardia seriolae. The phage shock protein A (PspA) and tellurium resistance protein D (TerD) were identified to be the immunodominant antigens of the wild-type N. seriolae strain ZJ0503 in our previous study. In an attempt to develop effective DNA vaccines against this pathogen, PspA and TerD were used as candidates to ligate with pcDNA3.1-Flag plasmids, respectively. In addition, the abilities of these two DNA vaccines to elicit various immune responses in hybrid snakehead and supply protective efficacy against artificial challenge with N. seriolae were determined in the present study. The results showed that intramuscular injection with pcDNA-PspA and pcDNA-TerD did not exhibit cytotoxic activities in hybrid snakehead via histopathological examination. Besides, hybrid snakehead immunization with pcDNA-PspA and pcDNA-TerD could increase several non-specific immune paraments in serum, including LYZ, POD, ACP, AKP and SOD activities. Meanwhile, the pcDNA-TerD DNA vaccine could induce strongly specific antibody (IgM) titer in hybrid snakehead with a relative percent of survival (RPS) value of 83.14% against N. seriolae, while that of pcDNA-PspA DNA vaccine was displayed comparably low IgM titer with RPS value of 57.83%. Furthermore, quantitative real-time PCR assays presented that the expression of immune-related genes (MHCIα, MHCIIα, CD4, CD8α, IL-1ß and TNFα) were up-regulated to various degrees after vaccination with pcDNA-PspA or pcDNA-TerD, indicating that these two DNA vaccines were able to boost humoral and cell-mediated immune responses in hybrid snakehead. Taken together, both the pcDNA-PspA and pcDNA-TerD DNA vaccines were proved to be safe, immunogenic and effective in protecting hybrid snakehead against N. seriolae infection, which can promote the development and application of DNA vaccines to control fish nocardiosis in aquaculture.

The protective efficacy of recombinant hypoxic response protein 1 of Nocardia seriolae in largemouth bass (Micropterus salmoides).

Nocardia seriolae has become one of the major pathogens affecting the aquaculture industry and causes Nocardiosis, a highly devastating disease of marine and freshwater fish that leads to severe economic losses. Therefore, research efforts towards developing efficacious vaccines to control this disease are of high importance. In this study, the hypoxic response protein 1 (HRP1) cloned into pET32a vector was expressed, and produced in Escherichia coli strain BL21 (DE3). The antigenicity of purified recombinant TRX-tagged HRP (rHRP1) was analysed by western blotting using largemouth bass anti-N. seriolae sera. The results showed that largemouth bass anti-N. seriolae sera could specifically detect a 33 kDa rHRP1 protein. Further, the vaccine efficacy of rHRP1 was evaluated in a largemouth bass fish model by calculating the relative percent survival (RPS). rHRP1 incurred an RPS of 73.33% as compared to the control group. Immunological analysis showed that rHRP1 could produce significantly higher serum concentrations of anti-N. seriolae antibodies and serum lysozyme activity as compared to the control groups. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that rHRP1 significantly enhanced the expression of immune-related genes, such as IL-12p40, IL-8, IL-1ß, TNFα, IFNγ, NKEF, MHCIα, MHCIIα, CD4-1, CD8α, IgM, NF-κß, STAT3, IRF4, RORα, and CCL20. These results indicate that rHRP1 may be a promising vaccine candidate against nocardiosis.

Development of DNA vaccines encoding ribosomal proteins (RplL and RpsA) against Nocardia seriolae infection in fish.

Nocardia seriolae, a Gram-positive pathogen, has been identified as the causative agent of fish nocardiosis. DNA vaccination has been proven to be effective in conferring protection against bacterial infection in fish. The 30S ribosomal protein S1 (RpsA) and 50S ribosomal protein L7/L12 (RplL) were identified to be the common immunodominant antigens of three fish pathogenic Nocardia (N. seriolae, N. salmonicida and N. asteroids) by immunoproteomics profiling in our previous study. In current study, the immunogenicity and protective efficacy of two DNA vaccines encoding RplL and RpsA were evaluated and compared in hybrid snakehead. The results showed vaccination of hybrid snakehead with the pcDNA-RplL and pcDNA-RpsA DNA vaccines provided protective efficacy with relative percentage survival (RPS) of 78.31% and 71.08%, respectively. Meanwhile, the immune response of hybrid snakehead induced by these two DNA vaccines were investigated, and it revealed that the non-specific immunity parameters (serum lysozyme (LYZ), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP) and superoxide dismutase (SOD) activities), specific antibody (IgM) production and immune-related genes expression (MHCIα, MHCIIα, CD4, CD8α, IL-1ß and TNFα) were significantly increased compared with the corresponding control groups after immunization. Taken together, these results indicated that both pcDNA-RplL and pcDNA-RpsA DNA vaccines could boost the innate, humoral and cellular immune responses in hybrid snakehead and show highly protective efficacy against fish nocardiosis, suggesting that ribosomal proteins RplL and RpsA were promising candidates for DNA vaccines and it will promote the vaccine development against fish nocardiosis.

Identification of common antigens of three pathogenic Nocardia species and development of DNA vaccine against fish nocardiosis.

Fish nocardiosis is a chronic granulomatous bacterial disease and three pathogens have been reported so far, including Nocardia asteroids, N. seriolae and N. salmonicida. However, the absence of antigen markers is a bottleneck for developing effective vaccines against fish nocardiosis. In this study, the antigenicity of whole-cell protein of these three pathogenic Nocardia species were profiled by immunoproteomic analysis and 7 common immunogenic proteins were identified as follows: molecular chaperone DnaK (DnaK), molecular chaperone GroEL (GroEL), 30 S ribosomal protein S1 (RpsA), TerD family protein (TerD), FHA domain-containing protein (FHA), 50 S ribosomal protein L7/L12 (RplL) and PspA/IM30 family protein (PspA). Furthermore, the DNA vaccine encoding FHA gene against fish nocardiosis was developed and its efficacy was investigated in hybrid snakehead. The results suggested that it needed at least 7 d to transport pcDNA-FHA DNA vaccine from injected muscle to head kidney, spleen and liver and stimulate host's immune system for later protection. In addition, non-specific immunity paraments (serum lysozyme (LYZ), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP) and superoxide dismutase (SOD) activities), specific antibody (IgM) titers production and immune-related genes (MHCIα, MHCIIα, CD4, CD8α, IL-1ß and TNFα) were used to evaluate the immune response induced in pcDNA-FHA vaccinated hybrid snakehead, it proved that all these mentioned immune activities were significantly enhanced after immunization. The results also showed hybrid snakehead vaccinated with pcDNA-FHA had higher survival rate (79.33%) compared with the controls after challenge with N. seriolae, indicating that the pcDNA-FHA DNA vaccine can supply immune protection against N. seriolae infection. Taken together, this study may warrant further development of these common immunogenic proteins as the antigens for vaccine or diagnosis and facilitate the prevention and treatment of fish nocardiosis.

Nocardia infection in kidney transplant recipients: A single-center experience.

BACKGROUND: Data on Nocardia infection in kidney transplant patients remain limited. METHODS: A chart review of patients with a history of kidney transplant and one positive culture for Nocardia between 1999 and 2019 was performed. RESULTS: Ten patients (0.1%) had a Nocardia infection. Eight were deceased donor kidney transplant recipients, and the mean age at the time of transplant was 56.0 ± 14.5 years. Nocardia infection occurred at a median of 12 months (range, 6-102) after transplant with half of the cases within 1 year. Breakthrough Nocardia infection occurred in five patients receiving daily double-strength (160/800 mg) TMP-SMX as prophylaxis. Half of the patients had comorbid CMV infection at diagnosis. The most common site involved was the lung. TMP-SMX was the most frequently used antimicrobial agent for treating Nocardia infection (9 of 10); it was administered as single-drug therapy (4 of 10) or as combination therapy with other antimicrobials (5 of 10). Overall mortality was 60% with 30% attributable mortality within a mean of 3.3 ± 7.7 weeks after a diagnosis of Nocardia. DISCUSSION: TMP-SMX prophylaxis did not appear to protect against Nocardia but did appear to be associated with less severe disease. Overall outcomes remain poor, and infection can occur outside the traditional window.

Comparison of protective efficacy between two DNA vaccines encoding DnaK and GroEL against fish nocardiosis.

Fish nocardiosis is a chronic granulomatous bacterial disease mainly caused by three pathogenic bacteria, including Nocardia seriolae, N. asteroids and N. salmonicida. Molecular chaperone DnaK and GroEL were identified to be the common antigens of the three pathogenic Nocardia species in our previous studies. To evaluate the immune protective effect of two DNA vaccines encoding DnaK or GroEL against fish nocardiosis, hybrid snakehead were vaccinated and the immune responses induced by these two vaccines were comparatively analyzed. The results suggested it needed at least 7 d to transport DnaK or GroEL gene from injected muscle to head kidney, spleen and liver and stimulate host's immune system for later protection after immunization by DNA vaccines. Additionally, non-specific immunity parameters (serum lysozyme (LYZ), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP) and superoxide dismutase (SOD) activities), specific antibody (IgM) production and immune-related genes (MHCIα, MHCIIα, CD4, CD8α, IL-1ß and TNFα) were used to evaluate the immune responses induced in vaccinated hybrid snakehead. It proved that all the above-mentioned immune activities were significantly enhanced after immunization with these two DNA vaccines. The protective efficacy of pcDNA-DnaK and pcDNA-GroEL DNA vaccines, in terms of relative percentage survival (RPS), were 53.01% and 80.71% respectively. It demonstrated that these two DNA vaccines could increase the survival rate of hybrid snakehead against fish nocardiosis, albeit with variations in immunoprotective effects. Taken together, these results indicated that both pcDNA-DnaK and pcDNA-GroEL DNA vaccines could boost the innate, humoral and cellular immune response in hybrid snakehead and show highly protective efficacy against fish nocardiosis, suggesting that DnaK and GroEL were promising vaccine candidates. These findings will promote the development of DNA vaccines against fish nocardiosis in aquaculture.

Nocardiosis in Sudan: Current Situation and Future Perspective.

BACKGROUND: Infections caused by Nocardia are rare, but misguided to clinicians, especially if there is a delay in the diagnosis and/or low response to chemotherapy. The incidence of nocardiosis is increasing constantly worldwide, and the situation is getting worse if we consider immunocompromised individuals, such as human immune virus (HIV) positive patients since they are at higher risk. Surgical amputation, although not common, but should be considered as a result in some cases that cause partial disability. AIMS: To throw light on the situation of nocardiosis in Sudan, the possible reasons for the increased prevalence are investigated and discussed the possible strategies for prevention and control. Data Review: PubMed investigations were adopted using terms that included nocardiosis in Sudan as well as in other parts of the world. Part of the review has been retrieved from the main library of the postgraduate college, University of Khartoum and University of Newcastle upon Tyne. FINDINGS: In Sudan, nocardiosis revealed wide geographical distribution; different cases were reported from western, middle as well as the northern parts of the country. Moreover, several clinical presentations were seen. While pulmonary, coetaneous and subcutaneous infections represent the primary types caused by Nocardia, disseminated infection in two or more organs had also been reported. As in all other infectious diseases, opportunistic nocardiosis is more prevalent among HIV patients. Zoonotic transmission of the disease was also proved; several cases of bovine and caprine mastitis were due to one or another species of Nocardia. The effect of ecology on the prevalence and pathogenicity of Nocardia is proved by the isolation of Nocardia and other actinomycetes from Sudanese soil, which represents the most probable source of infection. Regarding treatment, effective results are usually obtained by the use of sulfonamides and thirdgeneration cephalosporins. However, surgical interference is also used when necessary, such as in cases of drainage of abscesses. CONCLUSION: Since the description of Nocardia by Edmond Nocard in 1888, it started to be well known worldwide. In Sudan, however, the awareness regarding this bacterium is still below the level and is only due to the end of the fifties of the twentieth century, which is relatively late. Hence, attention towards this neglected pathogen may lead to early recognition and prompt treatment, resulting in complete cure.

Adjuvant effect in aquaculture fish of cell-wall glycolipids isolated from acid-fast bacteria.

Mycobacteriosis and nocardiosis in cultured fish caused by infections with acid-fast bacteria, are responsible for large economic losses globally. In this study, we suggest a novel adjuvant using glycolipids that activates host immune systems. The immune response to glycolipids stimulation was investigated using ginbuna crucian carp. Ginbuna vaccinated with FKC (formalin-killed cells) + glycolipids isolated from Mycobacterium sp., upregulated inflammatory- and Th1-related cytokines, and a DTH (delayed-type hypersensitivity) response was confirmed only in ginbuna vaccinated with FKC + glycolipids. These observations suggest that glycolipids activated host innate and cell-mediated immunity. Subsequently, we evaluated the adjuvant effect of glycolipids against amberjack nocardiosis. In a challenge test, a higher survival rate was observed in amberjack vaccinated with FKC + glycolipids emulsified with conventional oil adjuvant than in fish vaccinated with FKC + oil adjuvant without glycolipids. Therefore, glycolipids potentially could be used as a practical, economical and safe adjuvant for aquaculture fish.

A 20-year experience with nocardiosis in solid organ transplant (SOT) recipients in the Southwestern United States: A single-center study.

BACKGROUND: Nocardiosis is a life-threatening opportunistic infection. Solid organ transplant (SOT) recipients are at higher risk (incidence 0.04%-3.5%) of developing nocardiosis. Rate of nocardiosis in the Southwestern US may be high due to environmental factors. METHODS: We performed a retrospective review study on 54 SOT patients diagnosed with Nocardia between 1997 and 2016 at our center. To explore the association of various risk factors with both the development of disseminated disease and mortality, a series of Fisher's exact tests was used. FINDINGS: Incidence of nocardiosis in SOT patients was 2.65%. Fisher's exact tests revealed no association between development of disseminated disease and the following variables: transplant rejection (P = 1), elevated tacrolimus levels (P = .4), and CMV viremia (P = .06). Also, we did not find any association between mortality and the variables we evaluated: type of transplant, transplant rejection, renal failure, disseminated nocardia, and patient's age. Overall mortality and 1-year mortality were 17% and 11%. INTERPRETATION: Based on our findings, daily 1 DS TMP/SMX prophylaxis did not appear to provide reliable protection against nocardiosis. However, we could not state definitely that TMP/SMX prophylaxis was or wasn't protective because of lack control group. None of the Fisher's exact tests revealed associations between the tested risk factors and either disease dissemination or mortality. This could be due to a true lack of association between the variables in each pair. However, it is also likely that our relatively small sample size limited our power to detect underlying relationships that may be present. Compared with other studies, 1-year mortality was lower at our institution (11% vs 16%).