Evidence of Renal Infection in Fatal Cases of 2009 Pandemic Influenza A (HI NI)

The 2009 pandemic influenza A (H1N1) caused significant morbidity and mortality. Acute lung injury is the hallmark of the disease, but multiple organ system dysfunction can develop and lead to death. Therefore, we sought to investigate whether there was postmortem evidence of H1N1 presence and virus-induced organ injury in autopsy specimens. Five cases in which patients died of influenza A (H1N1) virus infection were studied. The lungs of all patients showed macroscopic and microscopic findings already described for H1N1 (consolidation, edema, hemorrhage, alveolar damage, hyaline membrane, and inflammation), and H1N1 viruses were present in alveolar cells in immunochemical studies. Acute tubular necrosis was present in all cases, but there was no evidence of direct virus-induced kidney injury. Nevertheless, H1N1 viruses were found in the cytoplasm of glomerular macrophages in the kidneys of 4 patients. Therefore, our data provide strong evidence that H1N1 presence is not restricted to the lungs.

Fungal infection by Paracoccidioides brasiliensis mimicking bone tumor

Paracoccidioides brasiliensis infection causes a systemic mycosis originally described in Latin America but with Current reports of worldwide distribution. The clinical presentation of paracoccidiodomycosis as an isolated long-bone lesion in children is quite unusual. This article describes a 10-year-old male with a lytic femoral bone lesion caused by P. brasiliensis infection that was first suspected of being of neoplasic etiology. The text also emphasizes the importance of including endemic fungal infections in the differential diagnosis of bone lesions.

Cutting Edge: Nucleotide-Binding Oligomerization Domain 1-Dependent Responses Account for Murine Resistance against Trypanosoma cruzi Infection

An effective innate immune recognition of the intracellular protozoan parasite Trypanosoma cruzi is critical for host resistance against Chagas disease, a severe and chronic illness that affects millions of people in Latin America. In this study, we evaluated the participation of nucleotide-binding oligomerization domain (Nod)like receptor proteins in host response to T cruzi infection and found that Nod1-dependent, but not Nod2-dependent, responses are required for host resistance against infection. Bone marrow-derived macrophages from Nod1(-/-) mice showed an impaired induction of NF-kappa B-dependent products in response to infection and failed to restrict T cruzi infection in presence of IFN-gamma. Despite normal cytokine production in the sera, Nod1(-/-) mice were highly susceptible to T cruzi infection, in a similar manner to MyD88(-/-) and NO synthase 2(-/-) mice. These studies indicate that Nod1-dependent responses account for host resistance against T cruzi infection by mechanisms independent of cytokine production. The Journal of Immunology, 2010, 184: 1148-1152.

Birth Prevalence and Natural History of Congenital Cytomegalovirus Infection in a Highly Seroimmune Population

Background. The natural history of congenital cytomegalovirus (CMV) infection is scarcely known in populations with high maternal CMV seroprevalence. This study evaluated the birth prevalence, clinical findings at birth, and hearing outcome in CMV-infected children from such a population. Methods. Consecutively born infants were screened for the presence of CMV in urine and/or saliva specimens during the first 2 weeks after birth. Neonatal clinical findings were recorded, and CMV-infected children were tested to document hearing function during follow-up. A subset of mothers of CMV-infected infants were prenatally tested for the presence of anti-CMV immunoglobulin G antibodies. Results. Congenital CMV infection was confirmed in 87 (1.08%; 95% confidence interval [CI], 0.86%-1.33%) of 8047 infants. Seven infants (8.1%; 95% CI, 3.3%-15.9%) had at least 1 clinical finding suggestive of CMV infection, and 4 (4.6%; 95% CI, 1.3%-11.3%) had 13 findings of systemic disease. Sensorineural hearing loss was found in 5 (8.6%; 95% CI, 2.9%-19.0%) of 58 children tested at a median age of 21 months. Bilateral profound hearing loss was observed in 2 children, and the hearing threshold was 160 decibels in all 5 children with hearing loss, including 2 children born to mothers with probable nonprimary CMV infection. Conclusions. The results of this large newborn screening study in a population with high CMV seroimmunity provide additional evidence that congenital CMV disease occurs in populations with high seroprevalence rates, with a similar incidence of CMV-related hearing loss to that reported in the offspring of women from populations in developed countries with lower rates of seroimmunity to CMV.

Development of chronic cardiomyopathy in canine Chagas disease correlates with high IFN-gamma, TNF-alpha, and low IL-10 production during the acute infection phase

When infected with Trypanosoma cruzi, Beagle dogs develop symptoms similar to those of Chagas disease in human beings, and could be an important experimental model for a better understanding of the immunopathogenic mechanisms involved in chronic chagasic infection. This study evaluates IL-10, IFN-gamma and TNF-alpha production in the sera, culture supernatant, heart and cervical lymph nodes and their correlation with cardiomegaly, cardiac inflammation and fibrosis in Beagle dogs infected with T. cruzi. Pathological analysis showed severe splenomegaly, lymphadenopathy and myocarditis in all infected dogs during the acute phase of the disease, with cardiomegaly, inflammation and fibrosis observed in 83% of the animals infected by T. cruzi during the chronic phase. The data indicate that infected animals producing IL-10 in the heart during the chronic phase and showing high IL-10 production in the culture supernatant and serum during the acute phase had lower cardiac alterations (myocarditis, fibrosis and cardiomegaly) than those with high IFN-gamma and TNF-alpha levels. These animals produced low IL-10 levels in the culture supernatant and serum during the acute phase and did not produce IL-10 in the heart during the chronic phase of the disease. Our findings showed that Beagle dogs are a good model for studying the immunopathogenic mechanism of Chagas disease, since they reproduce the clinical and immunological findings described in chagasic patients. The data suggest that the development of the chronic cardiac form of the disease is related to a strong Th1 response during the acute phase of the disease, while the development of the indeterminate form results from a blend of Th1 and Th2 responses soon after infection, suggesting that the acute phase immune response is important for the genesis of chronic cardiac lesions. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

Molecular characteristics of extended-spectrum beta-lactamase-producing Escherichia coli from Rio de Janeiro, Brazil

Twenty-five extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli clinical isolates from Rio de Janeiro, Brazil were characterized by isoelectric focusing, PCR and sequencing of bla(ESBL) genes, plasmid-mediated quinolone resistance determinants, phylogenetic groups, replicon typing, pulsed-field electrophoresis, and multilocus sequencing typing. Twenty-three (92%) ESBL-producing E. coli isolates were positive for bla(CTX-M) genes, aac(6`)-lb-cr, and qnrB. Genetic relatedness of ESBL producers clustered seven (28%) CTX-M-15-producing isolates as sequence type (ST) 410, clonal complex (CC) 23, and two (8%) as clone O25-ST131. Our results illustrate the predominance of phylo-group A (52%), ST410 (CC 23) and CTX-M-15 among ESBL-producing E. coli isolates from hospitals in Rio de Janeiro.

Case Report: Esophageal Histoplasmosis Associated with Disseminated Tuberculosis in Acquired Immunodeficiency Syndrome

Bacterial and fungal infections are common in acquired immunodeficiency syndrome (AIDS). Histoplasmosis is a common fungal disease in severely immunocompromised patients infected with human immunodeficiency virus (HIV) in endemic areas. In this population the most frequent form of presentation of histoplasmosis is disseminated, with the clinical manifestations being similar to those of disseminated tuberculosis. Esophageal histoplasmosis and the association of histoplasmosis with tuberculosis are infrequent. We report here a rare Case of esophageal histoplasmosis associated with disseminated tuberculosis in AIDS.

The involvement of CD4(+)CD25(+) T cells in the acute phase of Trypanosoma cruzi infection

The infection with Trypanosoma cruzi leads to a vigorous and apparently uncontrolled inflammatory response in the heart. Although the parasites trigger specific immune response, the infection is not completely cleared out, a phenomenon that in other parasitic infections has been attributed to CD4(+)CD25(+) T cells (Tregs). Then, we examined the role of natural Tregs and its signaling through CD25 and GITR in the resistance against infection with T. cruzi. Mice were treated with mAb against CD25 and GITR and the parasitemia, mortality and heart pathology analyzed. First, we demonstrated that CD4(+)CD25(+)GITR(+)Foxp3(+) T cells migrate to the heart of infected mice. The treatment with anti-CD25 or anti-GITR resulted in increased mortality of these infected animals. Moreover, the treatment with anti-GITR enhanced the myocarditis, with increased migration of CD4(+), CD8(+), and CCR5(+) leukocytes, TNF-alpha production, and tissue parasitism, although it did not change the systemic nitric oxide synthesis. These data showed a limited role for CD25 signaling in controlling the inflammatory response during this protozoan infection. Also, the data suggested that signaling through GITR is determinant to control of the heart inflammation, parasite replication, and host resistance against the infection. (C) 2008 Elsevier Masson SAS. All rights reserved.

A DNA vaccine candidate encoding the structural prM/E proteins elicits a strong immune response and protects mice against dengue-4 virus infection

A DNA vaccine expressing dengue-4 virus premembrane (prM) and envelope (E) genes was produced by inserting these genes into a mammalian expression plasmid (pCI). Following a thorough screening, including confirmation of protein expression in vitro, a recombinant clone expressing these genes was selected and used to immunize BALB/c mice. After 3 immunizations all the animals produced detectable levels of neutralizing antibodies against dengue-4 virus. The cytokines levels and T cell proliferation, detected ex vivo from the spleen of the immunized mice, showed that our construction induced substantial immune stimulation after three doses. Even though the antibody levels, induced by our DNA vaccine, were lower than those obtained in mice immunized with dengue-4 virus the levels of protection were high with this vaccine. This observation is further supported by the fact that 80% of the vaccine immunized group was protected against lethal challenge. In conclusion, we developed a DNA vaccine employing the genes of the prM and E proteins from dengue-4 virus that protects mice against this virus. (C) 2010 Elsevier Ltd. All rights reserved.

Recognition by toll-like receptor 2 induces antigen-presenting cell activation and Th1 programming during infection by Neospora caninum

Neospora caninum is an apicomplexan parasite responsible for major economic losses due to abortions in cattle. Toll-like receptors (TLRs) sense specific microbial products and direct downstream signaling pathways in immune cells, linking innate, and adaptive immunity. Here, we analyze the role of TLR2 on innate and adaptive immune responses during N. caninum infection. Inflammatory peritoneal macrophages and bone marrow-derived dendritic cells exposed to N. caninum-soluble antigens presented an upregulated expression of TLR2. Increased receptor expression was correlated to TLR2/MyD88-dependent antigen-presenting cell maturation and pro-inflammatory cytokine production after stimulation by antigens. Impaired innate responses observed after infection of mice genetically deficient for TLR2((-/-)) was followed by downregulation of adaptive T helper 1 (Th1) immunity, represented by diminished parasite-specific CD4(+) and CD8(+) T-cell proliferation, IFN-gamma:interleukin (IL)-10 ratio, and IgG subclass synthesis. In parallel, TLR2(-/-) mice presented higher parasite burden than wild-type (WT) mice at acute and chronic stages of infection. These results show that initial recognition of N. caninum by TLR2 participates in the generation of effector immune responses against N. caninum and imply that the receptor may be a target for future prophylactic strategies against neosporosis. Immunology and Cell Biology (2010) 88, 825-833; doi:10.1038/icb.2010.52; published online 20 April 2010

Evaluation of the Expression and Protective Potential of Leptospiral Sphingomyelinases

Leptospirosis is a zoonotic disease of global distribution, which affects both animals and humans. Pathogenic leptospires, the bacteria that cause this disease, require iron for their growth, and these spirochetes probably use their hemolysins, such as the sphingomyelinases, as a way to obtain this important nutrient from host red blood cells during infection. We expressed and purified the leptospiral sphingomyelinases Sph1, Sph2, Sph4, and SphH in a heterologous system. However, the recombinant proteins were not able to lyse sheep erythrocytes, despite having regular secondary structures. Transcripts for all sphingomyelinases tested were detected by RT-PCR analyses, but only Sph2 and SphH native proteins could be detected in Western blot assays using Leptospira whole extracts as well as in renal tubules of infected hamsters. Moreover, antibodies present in the serum of a human patient with laboratory-confirmed leptospirosis recognized Sph2, indicating that this sphingomyelinase is expressed and exposed to the immune system during infection in humans. However, in an animal challenge model, none of the sphingomyelinases tested conferred protection against leptospirosis.

Chemokines expression during Leptospira interrogans serovar Copenhageni infection in resistant BALB/c and susceptible C3H/HeJ mice

The role of innate immune responses in protection against leptospirosis remains unclear. We examined the expression of the chemokines CCL2/JE (MCP-1), CCL3/MIP-1 alpha (MIP-1 alpha) and CXCL1/KC (IL-8) regarding resistance and susceptibility to leptospirosis in experimental mice models BALB/c and C3H/HeJ, respectively. A virulent strain of Leptospira interrogans serovar Copenhageni was used in this study. Twenty-five animals of each mouse strain of C3H/HeJ and BALB/c, were infected intraperitoneally with 106 cells. Five un-infected animals of each strain were kept as control. Mortality of C3H/HeJ mouse was observed while BALB/c mice were asymptomatic. The presence of leptospire DNA in tissues of infected animals was demonstrated by PCR. Chemokines were measured in serum, spleen, liver, kidney and lung of both strains of animals using immunoenzymatic assay (ELISA). Elevations in the levels of chemokines MCP-1 and IL-8 occurred in all organs and sera of C3H/HeJ and BALB/c infected mice. The levels of MIP-1 alpha were lower when compared to MCP-1 and IL-8 in all analyzed organs, with a slight increase in liver and kidney. Our results indicate that the expression of inflammatory mediators can vary greatly, depending on the tissue and mouse strains. It is possible that the resistance to Leptospira can be partially correlated to the increase of MIP-1 alpha observed in BALB/c mice, while an increasing and a sustained expression of MCP-1 and IL-8 in the lungs of C3H/HeJ mice can be correlated to the severity and progression of leptospirosis. (C) 2009 Elsevier Ltd. All rights reserved.

Serum cardiac troponin I concentration in dogs with ehrlichiosis

Background: Ehrlichiosis is a multisystemic disease with the potential to cause cardiomyocyte injury in naturally infected dogs. Hypothesis: Myocardial injury occurs in dogs infected with Ehrlichia canis. Animals: One-hundred and ninety-four dogs from Brazil with clinical and laboratory abnormalities indicative of ehrlichiosis. Sixteen healthy dogs served as controls. Methods: Electrocardiogram, echocardiogram, noninvasive blood pressure measurement, and serum cardiac troponin I (cTnI) concentrations were evaluated. Serologic assays and PCR determined the exposure and infection status for E. canis, Anaplasma spp., Babesia canis vogeli, Bartonella spp., Borrelia burgdorferi, Dirofilaria immitis, Ehrlichia chaffeensis, Ehrlichia ewingii, Leishmania chagasi, and spotted-fever group Rickettsia. Dogs were assigned to groups according to PCR status: E. canis infected, infected with other vector-borne organisms, sick dogs lacking PCR evidence for infection, and healthy controls. Results: E. canis-infected dogs had higher serum cTnI concentrations than controls (median: 0.04 ng/dL; range 0.04-9.12 ng/dL; control median: 0.04 ng/dL; range: 0.04-0.10 ng/dL; P = .012), and acute E. canis infection was associated with myocardial injury (odds ratio [OR]: 2.67, confidence interval [CI] 95%: 1.12-6.40, P = .027). Severity of anemia was correlated with increased risk of cardiomyocyte damage (r = 0.84, P < .001). Dogs with clinical signs of systemic inflammatory response syndrome (SIRS) were at higher risk for myocardial injury than were other sick dogs (OR: 2.55, CI 95%: 1.31-4.95, P = .005). Conclusions and Clinical Importance: Acute infection with E. canis is a risk factor for myocardial injury in naturally infected Brazilian dogs. Severity of anemia and SIRS might contribute to the pathophysiology of myocardial damage.

Experimental infection of capybaras Hydrochoerus hydrochaeris by Rickettsia rickettsii and evaluation of the transmission of the infection to ticks Amblyomma cajennense

The present study evaluated the infection of capybaras (Hydrochoerus hydrochaeris) by Rickettsia rickettsii and their role as amplifier hosts for horizontal transmission of R. rickettsii to Amblyomma cajennense ticks. Two groups of two capybaras each were evaluated: on day 0, group 1 (G1) was infested by R. rickettsii-infected ticks, and group 2 (G2) was inoculated intraperitoneally with R. rickettsii. Two additional groups were control groups, not exposed to R. rickettsii, being CG1 group the control of G1, and CG2 group the control of G2. Capybara rectal temperature was measured daily. Blood samples were collected every 3 days during 30 days, and used to (i) inoculate guinea pigs intraperitoneally; (ii) DNA extraction followed by real-time PCR targeting the rickettsial gene gltA; (iii) hematology; (iv) detection of R. rickettsii-reactive antibodies by indirect immunofluorescence assay (IFA). Blood was also collected from G I capybaras every approximate to 10-30 days till the 146th day, to be tested by serology. Capybaras were infested by uninfected A. cajennense nymphs from the 3rd to the 18th day. Engorged nymphs were collected, allowed to molt to adults in an incubator. Thereafter, the subsequent flat ticks were tested by PCR. All G1 and G2 capybaras became infected by R. rickettsii, as demonstrated by guinea pig inoculation and seroconversion, but they showed no fever. Rickettsemia was continually detected from the 6th (G2 capybaras) or 9th (G1 capybaras) to the 18th day post inoculation or infestation with R. rickettsii-infected ticks. A total of 20-25% and 30-35% of the flat ticks previously fed on G1 and G2 capybaras, respectively, became infected by R. rickettsii. The study demonstrated that R. rickettsii was capable to infect capybaras without causing clinical illness, inducing rickettsemia capable to cause infection in guinea pigs and ticks. Our results indicate that capybaras act as amplifier host of R. rickettsii for A. cajennense ticks in Brazil. (c) 2008 Elsevier B.V. All rights reserved.

Ecology of Rickettsia in South America

Until the year 2000, only three Rickettsia species were known in South America: (i) Rickettsia rickettsii, transmitted by the ticks Amblyomma cajennense, and Amblyomma aureolatum, reported in Colombia, Argentina, and Brazil, where it is the etiological agent of Rocky Mountain spotted fever; (ii) Rickettsia prowazekii, transmitted by body lice and causing epidemic typhus in highland areas, mainly in Peru; (iii) Rickettsia typhi, transmitted by fleas and causing endemic typhus in many countries. During this new century, at least seven other rickettsiae were reported in South America: Rickettsia felis infecting fleas and the tick-associated agents Rickettsia parkeri, Rickettsia massiliae, Candidatus ""Rickettsia amblyommii,"" Rickettsia bellii, Rickettsia rhipicephali, and Candidatus ""Rickettsia andeanae. "" Among these other rickettsiae, only R. felis, R. parkeri and R. massiliae are currently recognized as human pathogens. R. rickettsii is a rare agent in nature, infecting : <= 1% individuals in a few tick populations. Contrastingly, R. parkeri, Candidatus ""R. amblyommii, "" R. rhipicephali, and R. bellii are usually found infecting 10 to 100% individuals in different tick populations. Despite rickettsiae being transmitted transovarially through tick generations, low infection rates for R. rickettsii are possibly related to pathogenic effect of R. rickettsii for ticks, as shown for A. aureolatum under laboratory conditions. This scenario implies that R. rickettsii needs amplifier vertebrate hosts for its perpetuation in nature, in order to create new lines of infected ticks (horizontal transmission). In Brazil, capybaras and opossums are the most probable amplifier hosts for R. rickettsii, among A. cajennense ticks, and small rodents for A. aureolatum.