B-1 Cells May Drive Macrophages Susceptibility to Trypanosoma cruzi Infection

B-1 cells can directly and indirectly influence the immune response. These cells are known to be excellent producers of natural antibodies and can secrete a variety of immunomodulatory molecules. They are also able to differentiate into B-1 cell-derived phagocytes (B-1CDP). B-1 cells can modulate macrophages to become less effective, and B-1CDP cells are more susceptible in infection models. In this work, we investigated the microbicidal ability of these cells in Trypanosoma cruzi infection in vitro. The results show that macrophages from BALB/c mice are more susceptible to infection than macrophages from XID mice. The resistance observed in macrophages from XID mice was abolished in the presence of B-1 cells, and this event seems to be associated with IL-10 production by B-1 cells, which may have contributed to the decrease of NO production. Additionally, B-1CDP cells were more permissive to intracellular T. cruzi infection than peritoneal macrophages. These findings strongly suggest that B-1 cells and B-1CDP cells have a potential role in the persistence of the parasite in host cells.

Human Kinetoplastid Protozoan Infections: Where Are We Going Next?

Kinetoplastida trypanosomatidae microorganisms are protozoan parasites exhibiting a developmental stage in the gut of insect vectors and tissues of vertebrate hosts. During the vertebrate infective stages, these parasites alter the differential expression of virulence genes, modifying their biological and antigenic properties in order to subvert the host protective immune responses and establish a persistent infection. One of the hallmarks of kinetoplastid parasites is their evasion mechanisms from host immunity, leading to disease chronification. The diseases caused by kinetoplastid parasites are neglected by the global expenditures in research and development, affecting millions of individuals in the low and middle-income countries located mainly in the tropical and subtropical regions. However, investments made by public and private initiatives have over the past decade leveraged important lines of intervention that if well-integrated to health care programs will likely accelerate disease control initiatives. This review summarizes recent advances in public health care principles, including new drug discoveries and their rational use with chemotherapeutic vaccines, and the implementation of control efforts to spatially mapping the kinetoplastid infections through monitoring of infected individuals in epidemic areas. These approaches should bring us the means to track genetic variation of parasites and drug resistance, integrating this knowledge into effective stewardship programs to prevent vector-borne kinetoplastid infections in areas at risk of disease spreading.

Canine Macrophage DH82 Cell Line As a Model to Study Susceptibility to Trypanosoma cruzi Infection

Trypanosoma cruzi is an obligatory intracellular protozoan parasite, and it is the etiological agent of Chagas' disease that is endemic in the Americas. In addition to humans, a wide spectrum of mammals can be infected by T. cruzi, including dogs. Dogs develop acute and chronic disease, similar to human infection. T. cruzi can infect almost all cell types and after cell invasion, the metacyclics trypomastigotes localize in the cytoplasm, where they transform into amastigotes, the replicative form of T. cruzi in mammals. After amastigote multiplication and differentiation, parasites lyse host cells and spread through the body by blood circulation. In this work, we evaluated the in vitro ability of T. cruzi to infect a canine macrophage cell line DH82 compared with RAW264.7, a murine tissue culture macrophage. Our results have shown that the T. cruzi is able to infect, replicate and differentiate in DH82 cell line. We observed that following treatment with LPS and IFN-γ DH82 cells were more resistant to infection and that resistance was not related reactive oxygen species production in our system. In this study, we also found that DH82 cells became more susceptible to T. cruzi infection when cocultured with apoptotic cells. The analysis of cytokine production has showed elevated levels of the TGF-β, IL-10, and TNF-α produced by T. cruzi-infected canine macrophages. Additionally, we demonstrated a reduced expression of the MHC class II and CD80 by infected DH82 cell line.

Inhibitory effects of Trypanosoma cruzi sialoglycoproteins on CD4+ T cells are associated with increased susceptibility to infection

Background

The Trypanosoma cruzi infection is associated with severe T cell unresponsiveness to antigens and mitogens characterized by decreased IL-2 synthesis. Trypanosoma cruzi mucin (Tc Muc) has been implicated in this phenomenom. These molecules contain a unique type of glycosylation consisting of several sialylated O-glycans linked to the protein backbone via N-acetylglucosamine residues.

Methodology/Principal Findings

In this study, we evaluated the ability of Tc Muc to modulate the activation of CD4⁺ T cells. Our data show that cross-linking of CD3 on naïve CD4⁺ T cells in the presence of Tc Muc resulted in the inhibition of both cytokine secretion and proliferation. We further show that the sialylated O-Linked Glycan residues from tc mucin potentiate the suppression of T cell response by inducing G1-phase cell cycle arrest associated with upregulation of mitogen inhibitor p27^kip1. These inhibitory effects cannot be reversed by the addition of exogenous IL-2, rendering CD4⁺ T cells anergic when activated by TCR triggering. Additionally, in vivo administration of Tc Muc during T. cruzi infection enhanced parasitemia and aggravated heart damage. Analysis of recall responses during infection showed lower frequencies of IFN-γ producing CD4⁺ T cells in the spleen of Tc Muc treated mice, compared to untreated controls.

Conclusions/Significance

Our results indicate that Tc Muc mediates inhibitory efects on CD4⁺ T expansion and cytokine production, by blocking cell cycle progression in the G1 phase. We propose that the sialyl motif of Tc Muc is able to interact with sialic acid-binding Ig-like lectins (Siglecs) on CD4⁺ T cells, which may allow the parasite to modulate the immune system.

Predicted annual costs for inpatients with diabetes and foot ulcers in a developing country-a simulation of the current situation in Brazil

AIMS

The objective of this cost-of-illness analysis was to quantify the annual costs associated with hospital admission for people with diabetes and foot ulcers in Brazil.

METHODS

A hypothetical cohort was simulated using a decision tree model. Prevalence and incidence rates and clinical outcomes were estimated from published studies and applied to the general Brazilian population over 30 years. Costs were quoted in Brazilian real (BRL) and converted to US dollars ($US) at the 2008 currency exchange rate ($US1 = BRL 1.64). In the sensitivity analysis, we reduced and increased rates to assess the robustness of the cost estimates.

RESULTS

In this hypothetical cohort there are 6.48 million (95% confidence interval 4.47-7.12) Brazilians citizens with Type 2 diabetes. Each year, approximately 323,000 (89,500-484,500) of these people develop foot ulcers and almost 97,200 (17,900-169,600) require hospital admission as a result. Each year, almost 46,300 (8500-80,900) limb amputations and 12,400 (2300-21,700) deaths occur as a result of diabetic foot disease in Brazil. The annual cost associated with these hospital admissions is estimated to be almost $US264m ($US51m-461m). The estimated cost for patients with amputation is nearly $US128m ($US24.5m-222.3m).

CONCLUSIONS

Our model shows that the social and economic impact of diabetic foot disease in Brazil is high. Government decision makers should reflect on the current situation and provide organized foot care throughout the whole country.

Increased immunoglobulin secretion by B lymphocytes from Trypanosoma cruzi infected mice after B lymphocytes-natural killer cell interaction

In the present study, we investigated whether natural killer (NK) cells modulate immunoglobulin (Ig) secretion by B cells from Trypanosoma cruzi-infected mice. B cells from infected mice increased IgM and IgG2a secretion in the presence of a NK cell line, and this response was cell contact-dependent. Stimulation of splenic B cells with polyinosinic-polycytidylic acid, a NK cell activator, also increased Ig secretion by B cells from infected mice. B cells from infected mice expressed higher levels of the B7.2 molecule. Our results suggest that NK cells may be involved in the control of the abnormal B cell activation observed during T. cruzi infection.

Increased susceptibility of Fas ligand-deficient gld mice to Trypanosoma cruzi infection due to a Th2-biased host immune response

Infection of BALB/c mice with Trypanosoma cruzi resulted in up-regulated expression of Fas and Fas ligand (FasL) mRNA by splenic CD4+ T cells, activation-induced CD4+ T cell death (AICD), and in Fas: FasL-mediated cytotoxicity. When CD4+ T cells from infected mice were co-cultured with T. cruzi-infected macrophages, onset of AICD exacerbated parasite replication. CD4+ T cells from T. cruzi-infected FasL-deficient BALB gld/gld mice had no detectable AICD in vitro and their activation with anti-TCR did not exacerbate T. cruzi replication in macrophages. However, infection of BALB gld/gld mice with T. cruzi resulted in higher and more prolonged parasitemia, compared to wild-type mice. Secretion of Th2 cytokines IL-10 and IL-4 by CD4+ T cells from infected gld mice was markedly increased, compared to controls. In addition, in vivo injection of anti-IL-4 mAb, but not of an isotype control mAb, reduced parasitemia in both gld and wild-type mice. These results indicate that, besides controlling CD4+ T cell AICD and parasite replication in vitro, an intact Fas: FasL pathway also controls the host cytokine response to T. cruzi infection in vivo, being required to prevent an exacerbated Th2-type immune response to the parasite.

Proapoptotic activity of a Trypanosoma cruzi ceramide-containing glycolipid turned on in host macrophages by IFN-gamma

The effects of glycoinositolphospholipid (GIPL), from the pathogenic protozoan Trypanosoma cruzi, and its isolated glycan and lipid (dihydroceramide) components, were investigated in J774 cells and primary macrophages. Isolated GIPL ceramide, but not intact GIPL or its glycan, induced intense fluid phase endocytosis when added exogenously. In the presence of the cytokine IFN-gamma, GIPL ceramide induced marked apoptosis in J774 cells and macrophages, independent of nitric oxide secretion. When cells were preincubated with the GIPL-derived glycan chain, addition of intact GIPL induced macrophage apoptosis in the presence of IFN-gamma. Synthetic C2-dihydroceramide also induced apoptosis in the presence of IFN-gamma. Induction of apoptosis in T. cruzi-infected macrophages by GIPL ceramide plus IFN-gamma led to increased parasite release compared with IFN-gamma treatment alone. Viable parasites released comprised both infective trypomastigote and spheromastigote forms. These results identify a novel pathway by which T. cruzi glycosylphosphatidylinositol family molecules affect host macrophages, with implications for the infectious process.

Activation-induced T cell death exacerbates Trypanosoma cruzi replication in macrophages cocultured with CD4+ T lymphocytes from infected hosts

Activation-induced cell death (AICD) of CD4+ T lymphocytes was described in infection with Trypanosoma cruzi, but a role for AICD in modulating parasite spread in host cells has not been investigated. In this study, replication of T. cruzi in vitro in murine macrophage (Mphi) monolayers was investigated. Long term (5 to 13 day) replication of infective (trypomastigote) T. cruzi forms was blocked by supernatants from activated (anti-TCR) CD4+ T cells of infected mice or by rIFN-gamma. However, when CD4+ T cells from infected mice were cocultured with Mphi and activated by anti-TCR, marked exacerbation of trypomastigote growth in Mphi ensued. The deleterious effect required contact between T cells and infected Mphi. Both anti-Fas and TCR activation killed a proportion of CD4+ T cells. Ly-6 activation did not induce AICD and did not exacerbate parasite growth. However, Fas-mediated killing of T cells before Ly-6 activation led to exacerbated parasite growth. Although a minor population, Fas-susceptible cells were the major source of IFN-gamma production by activated T cells. Addition of a neutralizing anti-Fas ligand antibody blocked 50 to 60% of CD4+ T cell AICD and reduced trypomastigote growth in T/Mphi cocultures stimulated by anti-TCR. The results demonstrate that in CD4+ T cells from infected mice, the onset of AICD selectively ablates IFN-gamma production and up-regulates parasite replication in Mphi in vitro. These findings suggest a deleterious role for AICD in T. cruzi infection.

Delivery by Trypanosoma cruzi of proteins into the MHC class I antigen processing and presentation pathway

Class I MHC-restricted T cell responses have been shown to be critical for the development of immune resistance to Trypanosoma cruzi in mice. However, to date, no antigenic targets of this anti-parasite response have been characterized. We have analyzed the characteristics of potential T. cruzi CTL target molecules by expression of the model CTL target molecule chicken OVA in different cellular compartments of T. cruzi. OVA (amino acids 139-385) was expressed as a secretory, cytoplasmic, transmembrane, or glycosylphosphatidylinositol-anchored protein in T. cruzi transfectants. Host cells infected with T. cruzi transfectants that secreted or released OVA, but not those producing cytoplasmic or transmembrane forms of OVA, could process and present OVA peptide via the class I MHC pathway, as indicated by the stimulation of OVA-specific CD8+ T cell hybridomas and the cytolysis of host cells infected with OVA-secreting parasites by OVA-specific CTLs. In addition, infection of mice with OVA-secreting parasites elicited the production of OVA-specific CTLs. These studies demonstrate the ability to target proteins to specific cellular compartments in T. cruzi using either trypanosomal or mammalian signal sequences. Furthermore, these results suggest that proteins secreted or released by T. cruzi in infected cells are a major source of peptides for MHC class I presentation and for the generation of parasite-specific CTL.

Delivery by Trypanosoma cruzi of proteins into the MHC class I antigen processing and presentation pathway

Class I MHC-restricted T cell responses have been shown to be critical for the development of immune resistance to Trypanosoma cruzi in mice. However, to date, no antigenic targets of this anti-parasite response have been characterized. We have analyzed the characteristics of potential T. cruzi CTL target molecules by expression of the model CTL target molecule chicken OVA in different cellular compartments of T. cruzi. OVA (amino acids 139-385) was expressed as a secretory, cytoplasmic, transmembrane, or glycosylphosphatidylinositol-anchored protein in T. cruzi transfectants. Host cells infected with T. cruzi transfectants that secreted or released OVA, but not those producing cytoplasmic or transmembrane forms of OVA, could process and present OVA peptide via the class I MHC pathway, as indicated by the stimulation of OVA-specific CD8+ T cell hybridomas and the cytolysis of host cells infected with OVA-secreting parasites by OVA-specific CTLs. In addition, infection of mice with OVA-secreting parasites elicited the production of OVA-specific CTLs. These studies demonstrate the ability to target proteins to specific cellular compartments in T. cruzi using either trypanosomal or mammalian signal sequences. Furthermore, these results suggest that proteins secreted or released by T. cruzi in infected cells are a major source of peptides for MHC class I presentation and for the generation of parasite-specific CTL.

Prevention of suicide phenomenon in aeromonads

Clinical isolates of Aeromonas (13 Aeromonas caviae), 8 Aeromonas hydrophila, 3 Aeromonas spp., and 2 Aeromonas media recovered from diarrheal feces of children were submitted to the suicide phenomenon test and investigated at intervals of 24 h for up to 120 h. The same isolates were also stimulated by repeated passages in broth for ten days before the test. After the bacterial stimulus, a decreases in the number of aeromonads with suicidal capacity was observed. The suicide phenomenon was expressed after 72 h of incubation in only some isolates. The results show that the suicide phenomenon can be prevented by stimulation of bacterial metabolism.

Occurrence of Plesiomonas shigelloides in water environments of Rio de Janeiro city

Fresh and salt water samples analyzed in Rio de Janeiro city showed the presence of Plesiomonas shigelloides. Forty-six strains were isolated from both environments. A high incidence of P. shigelloides was achieved in polluted fresh and salt waters as well as in samples from non-polluted streams. P. shigelloides isolates had biochemical characteristics similar to those already described in the literature. None of the isolates analyzed produced enterotoxin in the suckling mouse assay. Hemolytic activity against sheep and human type A erythrocytes was detected in the strains tested. The results of the antibiotic susceptibility tests indicated that all the isolates were susceptible to the cephalosporins, penicillins combined with a beta-lactamase inhibitor, aminoglycosides, imipenem, norfloxacin, tetracycline, chloramphenicol and trimethoprim-sulfamethoxazole. All the isolates were resistant to the penicillins.

Aeromonas species exhibit aggregative adherence to HEp-2 cells

Clinical and environmental isolates of Aeromonas species (five A. hydrophila isolates, three A. caviae isolates, and two A. sobria isolates) were tested for their adherence to HEp-2 cells. Clinical isolates of A. hydrophila and A. sobria exhibited aggregative adherence similar to that presented by enteroadherent-aggregative Escherichia coli. Bacterial aggregates adhered to cells with a typical "stacked-brick" appearance. In contrast, A. caviae strains showed a diffuse adherence pattern.

Quantification of Trypanosoma cruzi in the heart, lymph nodes and liver of experimentally inffected mice, using limiting dilution analysis

Limiting dilution analysis was used to quantify Trypanosoma cruzi in the lymph nodes, liver and heart of Swiss and C57Bl/10 mice. The results showed that, in Swiss and Bl/10 mice infected with T. cruzi Y strain, the number of parasites/mg of tissue increased during the course of the infection in both types of mice, although a greater number of parasites were observed in heart tissue from Swiss mice than from Bl/10. With regard to liver tissue, it was observed that the parasite load in the initial phase of infection was higher than in heart. In experiments using T. cruzi Colombian strain, the parasite load in the heart of Swiss and Bl/10 mice increased relatively slowly, although high levels of parasitization were nonetheless observable by the end of the infection. As for the liver and lymph nodes, the concentration of parasites was lower over the entire course of infection than in heart. Both strains thus maintained their characteristic tissue tropisms. The limiting dilution assay (LDA) proved to be an appropriate method for more precise quantification of T. cruzi, comparing favorably with other direct microscopic methods that only give approximate scores.

Serological survey for canine cutaneous and visceral leishmaniasis in areas at risk for transmission in Rio de Janeiro where prophylactic measures had been adopted

A serological survey for canine visceral (VL) and American cutaneous leishmaniasis (ACL) has been carried out during 1984-1989, to assess the effects of the prophylactic measures adopted in areas where there was a risk of transmission of the diseases in Rio de Janeiro. A previous serological survey (1982/83) had detected serum positive dogs as well as the human disease in these same areas. A total of 22,828 dogs have been examined in this last survey, 7,807 of which came from Campo Grande (VL and ACL area), 4,110 from Jacarepaguá (ACL area), 4,146 from Realengo, 3,879 from Bangu and 2,886 from Senador Camará, (three VL areas). The analysis of these results showed a notable reduction in the number of serum positive dogs, compared to those of the first survey of 1982/83 as follows: (a) in Campo Grande (VL and ACL) the infection rate of the first survey was 12.7%, against 0.62% of the second; (b) in Jacarepaguá (ACL) it decreased from 8.6% to 1.8% (c) in Bangu, Realengo and Senador Camará (VL) the rate decreased from 4.3% to 0.38%. The results indicate that this decrease was due to the prophylactic measures adopted in those areas.

[Ecological aspects of American tegumentary leishmaniasis: 8. Evaluation of the enzootic activity of Leishmania (Viannia) braziliensis, in forest and peridomiciliary environments of the Ribeira Valley region, São Paulo State, Brazil]

The evidence of mucocutaneous leishmaniasis transmission in the non-forest environment in the Ribeira Valley region, São Paulo, Brazil, has made this epidemiologic four years' study possible, viewing the enzootic activity of L. (V.) braziliensis. Furthermore, the natural infection in small mammals and the domestic dog population has been completed in collecting of phlebotomine sandflies in the forest and peridomiciliar environments. Positive test-results have only been found in resident dogs (Canis familiaris) with a rate of 5.6 and 2.4% for serological and parasitological test respectively. Among silvatic and synanthropic rodents collected, Oryzomys (Olygoryzomys) and Rattus rattus are pre-eminent having both been collected in equal proportions, in peridomiciliar environment. The sandfly Lutzomyia intermedia has contributed only with 166 feminine specimens due to insecticide (DDT) application on and in the human and domestic habitations. From the general epidemiologic standpoint the fragile L. (V.) braziliensis cycle in the unforested areas as well as the canine and small mammals roles as a domiciliar infection source are discussed, and their potencial in the dispersion of this parasite in the researched area is analysed too.

Trypanosoma cruzi: quantification in tissues of experimentally infected mice by limiting dilution analysis

A limiting dilution assay (LDA) was developed for the quantification of Trypanosoma cruzi in the heart and blood of infected mice. Three groups of swiss mice were injected ip with "CL", "Colombiana," and "Y" strains. At 1-day intervals after infection, blood and the heart were removed. Serial blood dilutions in LIT medium were performed and distributed in four groups of 24 microplate wells. The growth of parasite was visually checked in an inverted microscope. It was found that curves of parasitemia obtained by parasite counting in a hemocytometer or estimated by LDA were similar. A similar method was used to quantify parasites in the heart of mice. The heart was cut, washed, dried, and its weight was determined. The heart pieces were disrupted by passage through a mesh stainless-steel screen into LIT. Serial dilutions of the heart homogenate were made in LIT and added to at least 24 replicate microplate wells. Parasites were detectable earlier in the heart of mouse infected with Y strain when compared to CL and Colombiana strains. Parasites were detected in the heart of mice of all strains by 6 days after infection. This LDA for quantification of T. cruzi permits a more precise evaluation of the number of living parasites in infected tissues.

Indirect immunofluorescence test in New World leishmaniasis: serological and clinical relationship

The indirect immunofluorescence test (IF) for anti-Leishmania antibodies (IgG and IgM) was performed with sera from the following groups of individuals: 214 cutaneous leishmaniasis patients, 28 healthy subjects with positive Montenegro's skin test (MST), 29 healthy subjects with negative MST and 16 visceral leishmaniasis patients. The first four groups came from a suburban area of Rio de Janeiro (Jacarepaguá) where cutaneous leishmaniasis caused by Leishmania braziliensis braziliensis is endemic. It was observed that IF-IgM titers were significantly higher amongst the cutaneous leishmaniasis patients with less than four months of disease as compared to those with longer periods and that IF-IgG titers were significantly higher in patients with multiple lesions as compared to those with single lesions. The visceral leishmaniasis patients had IF-IgG titers significantly higher than those from cutaneous leishmaniasis patients. A group of 28 individuals selected amongst the 214 cutaneous leishmaniasis patients had their IF-titers (IgG and IgM) compared to those of the two control groups of healthy subjects from the endemic area, respectively with positive and negative MST. Significantly higher titers of IF-IgG and IF-IgM were found in the group with active disease. The same group of patients showed IF-IgG titers significantly lower at the end of the antimonial therapy than those observed during this treatment.

Canine American cutaneous leishmaniasis: a clinical and immunological study in dogs naturally infected with Leishmania braziliensis braziliensis in an endemic area of Rio de Janeiro, Brazil

Clinical and immunological findings from 35 dogs infected with Leishmania braziliensis braziliensis are described. The majority of the dogs had ulcerated single lesions on the ears. Sera from all infected dogs showed detectable Leishmania-induced antibodies using an indirect fluorescent antibody test. Antimonial therapy resulted in prompt healing of the lesions in 80.9% of the animals followed by a significant reduction in the anti-Leishmania antibody titers. However, treatment follow-up showed recurrences at the site of the primary lesion in 42.8% of the cases. These data were correlated with a persistence of the parasite in clinically healed lesions as well as with a negative intradermal test (leishmanin-delayed type hypersensitivity) observed in all animals but one.

A survey for American cutaneous and visceral leishmaniasis among 1,342 dogs from areas in Rio de Janeiro (Brazil) where the human diseases occur

There are areas in the periphery of Rio de Janeiro city where human cases of Visceral and/or Cutaneous Leishmaniasis occur. The parasites have been identified as Leishmania donovani and Leishmania braziliensis braziliensis respectively. A survey for Leishmaniasis was done among 1,342 dogs from those areas using an indirect immunofluorescent test. From the dogs, 616 came from areas where only human cases of Visceral Leishmaniasis occurred, 373 from an area where all human cases were of Cutaneous Leishmaniasis and 353 from a third area (Campo Grande) where both visceral and cutaneous human cases were detected. The prevalence of parasite antibody titers among dogs from areas of Cutaneous Leishmaniasis was significantly higher than that of Visceral Leishmaniasis (8.6% vs. 4.3%, p less than 0.02). The highest prevalence was observed among dogs from the area where both diseases are present (12.7%).

Detection of Yersinia enterocolitica heat-stable enterotoxin by suckling mouse bioassay

A comparison of heat-stable enterotoxins from Escherichia coli and Yersinia enterocolitica by the suckling mouse bioassay showed that whereas E. coli heat-stable enterotoxin evoked a maximum ratio of gut weight to remaining body weight after a 4-h incubation period, the maximum ratio for Y. enterocolitica was achieved at 2 h, decreasing thereafter to values regarded as negative (less than 0.083). This action of Y. enterocolitica heat-stable enterotoxin may give false-negative results for the standard suckling mouse bioassay.

Bacteriophage specificity in the identification of Yersinia pestis as compared with other enterobacteria

Bacteriophage typing of Yersinia pestis and the specificity of the phage among Enterobacteriaceae were investigated. The bacteriophage used for rapid identification of Y. pestis reacted with representative strains of all recognized species of Shigella as well as with Salmonella cholerae-suis. Reactive Shigella serotypes were Sh. dysenteriae 1 and 9, Sh. flexneri 2a, Sh. boydii 1 and 6, and Sh. sonnei. Patterns consisting of isolated plaques (two cases) or absence of plaques were observed when the routine test dilution (RTD) of the phage was used. Results were independent of the incubation temperature (20, 28 or 37 degrees C). Representative strains of Escherichia, Proteus, Providencia and Klebsiella were resistant to the bacteriophage even at 1000 X the RTD established for Y. pestis.

Anti-brucella agglutinins in bats and "Callithrix" monkeys

Anti-Brucella agglutinins were found in 5 of 53 (9.4%) vampire bats Desmodus rotundus, captured in the State of Bahia, Brasil. Two specimens of Diphylla ecaudata were negative. Fifty specimens of the small monkey, Callithrix penicillata, were also negative.