Detection of Neorickettsia sp. in Oligoryzomys flavescens rodent from a protected urban area in Buenos Aires City (Argentina).

Rodents play an important role in vector-borne pathogens cycle. To detect Anaplasma, Ehrlichia, Neorickettsia, Rickettsia and Borrelia species in rodents from a protected urban area in Buenos Aires City (Argentina) were analyzed 203 organ pools of Mus musculus, Oligoryzomys flavescens, Rattus norvegicus, Deltamys kempi and Scapteromys aquaticus by PCR. Only one O. flavescens (1.2%) was positive by PCR for 16S rRNA fragment for the Anaplasmataceae family and the sequence had 99.7% identity with Neorickettsia risticii. Plus, the sequence obtained for a fragment of the p51 gene for the genus Neorickettsia from positive sample had 95.3-96.1% identity with N. risticii found previously in bats Tadarida brasiliensis from Buenos Aires City. Our study presents the first finding of Neorickettsia in rodents from natural environment, but further studies are necessary about these vector-borne bacteria and the rol of rodents in its epidemiology.

Serotonin Type 2a Receptor in the Prefrontal Cortex Controls Perirhinal Cortex Excitability During Object Recognition Memory Recall.

Previous experiences can drive adaptive behavior based on different characteristics, including contextual ones. Indeed, contextual information can be used as a criterion to guide the recall of the most relevant memory trace and the inhibition of others. The medial Prefontal Cortex (mPFC) has been proposed as an area that plays a pivotal role in regulating the retrieval of memory traces in downstream regions. Also, we have shown that mPFC Serotonin 2a Receptors (5-HT2aR) modulates the retrieval of a contextually guided recognition memory task and modulates the retrieval and reconsolidation of memories in the Perirhinal Cortex (PRH). However, how the mPFC output mediated by the 5-HT2aR activity is modulating memory retrieval in the PRH is a question that remains unclear. To tackle this question, we analyzed neuronal activity in the PRH and mPFC, by measuring expression of the immediate early gene c-Fos. We combined behavioral, pharmacological and immunohistochemical techniques to examine how mPFC 5-HT2aR controls mPFC and the PRH activity. We found that blockade of mPFC 5-HT2aR increase the level of c-Fos expression in the PHR and that this increase correlates with animals' performance in the task. We also found an increase in c-Fos expression in the mPFC after mPFC 5-HT2aR blockade that does not correlate with the animals' behavioral response. However, these changes showed a significant correlation with those observed in the PRH. These results suggest that mPFC 5-HT2aR signaling may modulate the behavioral response during memory recall by controlling the neuronal activation in the PRH.

Molecular detection of Bartonella in fleas (Hexapoda, Siphonaptera) collected from wild rodents (Cricetidae, Sigmodontinae) from Argentina.

Bartonella are facultative intracellular Gram-negative bacteria, transmitted mainly by hematophagous arthropods, and the rodents act as a natural reservoir. Different species of Bartonella associated with rodents have been implicated as causing human disease. Studies from Argentina are scarce and no Bartonella from fleas have been reported previously. The present study investigated the presence of Bartonella spp. in fleas associated with sigmodontine rodents in four localities of the Santa Cruz Province, Argentina. In total, 51 fleas (four species) were analysed of which 41.2% were found to be positive for the gltA gene fragment via a nested polymerase chain reaction. All positive fleas were of the species Neotyphloceras crackensis from three different localities. Eight of the 21 amplified samples were sequenced, and the presence of three different genotypes was detected with an identity of 95.5-98.8% amongst themselves. Bartonella genotypes from American rodents and rodent fleas were recovered in a monophyletic group. Similarly, most of the Peruvian and all Argentinean variants constitute a natural group sister of the American remainder. The importance of the Bartonella spp. with respect to public health is unknown, although future studies could provide evidence of the possible involvement of N. crackensis in the Bartonella transmission cycles.

Isolation of Rickettsia massiliae from Rhipicephalus sanguineus Ticks, Buenos Aires (Argentina).

Rickettsia massiliae , a member of the spotted fever group of Rickettsia, was first isolated from a Rhipicephalus turanicus tick in France. In the New World, it has been detected in Rhipicephalus sanguineus ticks from different geographical locations in Argentina and the United States, but it has only been isolated in Arizona. The aim of this study was the isolation and genetic characterization of R. massiliae from R. sanguineus ticks collected from dogs in Buenos Aires city, Argentina. In total, 49 R. sanguineus ticks were collected from 10 dogs and grouped into 10 pools of 4-5 specimens. With a PCR assay, which detects a fragment of the Rickettsia genus-specific 23S-5S intergenic space, 1 pool of 5 ticks was found positive. Generated sequences exhibited 100% identity with R. massiliae . A new isolate, named CABA, was obtained from this pool by inoculating it into monolayers of Vero cells. Genotypic characteristics were determined, and results showed that fragments of the 23S-5S intergenic space, ompA, ompB, gltA, htrA, and sca1 genes had great similarity with R. massiliae strain Bar29 (Spain). Although few human cases have been confirmed for this pathogen, its circulation in urban areas is of great importance to public health. This isolation improves knowledge of the circulating pathogen and could improve future diagnostic processes as it allows the production of more specific antigens for serological testing.

[First isolation of Histoplasma capsulatum from the urban bat Eumops bonariensis]. / Primer aislamiento de Histoplasma capsulatum de murciélago urbano Eumops bonariensis.

We report the first isolation of Histoplasma capsulatum var. capsulatum from a male bat Eumops bonariensis captured in Buenos Aires city in 2003. The pathogen was recovered from spleen and liver specimens, and was identified by its phenotypic characteristics. PCR with primers 1283, (GTG)5, (GACA)4 and M13 was used to compare both bat isolates with 17 human isolates, 12 from patients residing in Buenos Aires city, and 5 from other countries of the Americas. The profiles obtained with the four primers showed that both bat isolates were identical to each other and closer to Buenos Aires patients than to the other isolates (similarity percentage: 91-100% and 55-97%, respectively). The high genetic relationship between bat isolates and those from patients living in Buenos Aires suggests a common source of infection. This is the first record of E. bonariensis infected with H. capsulatum in the world, and the first isolation of the fungus in the Argentinean Chiroptera population. In the same way as these wild mammals act as reservoir and spread the fungus in the natural environment, infection in urban bats could well be associated with the increase in histoplasmosis clinical cases among immunosuppressed hosts in Buenos Aires city.

Primer aislamiento de Histoplasma capsulatum de murciélago urbano Eumops bonariensis / First isolation of Histoplasma capsulatum from the urban bat Eumops bonariensis

Se comunica el primer aislamiento de Histoplasma capsulatum var. capsulatum de un murciélago macho de la especie Eumops bonariensis, capturado en la ciudad de Buenos Aires en 2003. Los aislamientos fueron recuperados de bazo e hígado e identificados fenotípicamente. Se los comparó por PCR, con 17 aislamientos clínicos, 12 de pacientes residentes en la ciudad de Buenos Aires y cinco de otros países de América, usando los iniciadores 1283, (GTG)5, (GACA)4 y M13. Con los cuatro iniciadores, los perfiles de los aislamientos de murciélago resultaron idénticos entre sí y más relacionados a los de pacientes de Buenos Aires que a los de otros países (porcentaje de similitud: 91-100% y 55-87%, respectivamente). La alta relación genética entre los aislamientos obtenidos del murciélago y de los humanos residentes en Buenos Aires sugiere una fuente común de infección. Este es el primer registro de E. bonariensis infectado con H. capsulatum en el mundo, y el primer aislamiento del hongo en la población de quirópteros de la Argentina. Así como estos mamíferos actúan como reservorio y dispersan el hongo en la naturaleza, la infección en murciélagos urbanos podría asociarse al elevado número de casos de histoplasmosis entre pacientes inmunodeprimidos en la ciudad de Buenos Aires.

We report the first isolation of Histoplasma capsulatum var. capsulatum from a male bat Eumops bonariensis captured in Buenos Aires city in 2003. The pathogen was recovered from spleen and liver specimens, and was identified by its phenotypic characteristics. PCR with primers 1283, (GTG)5, (GACA)4 and M13 was used to compare both bat isolates with 17 human isolates, 12 from patients residing in Buenos Aires city, and 5 from other countries of the Americas. The profiles obtained with the four primers showed that both bat isolates were identical to each other and closer to Buenos Aires patients than to the other isolates (similarity percentage: 91-100% and 55-97%, respectively). The high genetic relationship between bat isolates and those from patients living in Buenos Aires suggests a common source of infection. This is the first record of E. bonariensis infected with H. capsulatum in the world, and the first isolation of the fungus in the Argentinean Chiroptera population. In the same way as these wild mammals act as reservoir and spread the fungus in the natural environment, infection in urban bats could well be associated with the increase in histoplasmosis clinical cases among immunosuppressed hosts in Buenos Aires city.

Primer aislamiento de Histoplasma capsulatum de murciélago urbano Eumops bonariensis. / [First isolation of Histoplasma capsulatum from the urban bat Eumops bonariensis]

We report the first isolation of Histoplasma capsulatum var. capsulatum from a male bat Eumops bonariensis captured in Buenos Aires city in 2003. The pathogen was recovered from spleen and liver specimens, and was identified by its phenotypic characteristics. PCR with primers 1283, (GTG)5, (GACA)4 and M13 was used to compare both bat isolates with 17 human isolates, 12 from patients residing in Buenos Aires city, and 5 from other countries of the Americas. The profiles obtained with the four primers showed that both bat isolates were identical to each other and closer to Buenos Aires patients than to the other isolates (similarity percentage: 91-100

and 55-97

, respectively). The high genetic relationship between bat isolates and those from patients living in Buenos Aires suggests a common source of infection. This is the first record of E. bonariensis infected with H. capsulatum in the world, and the first isolation of the fungus in the Argentinean Chiroptera population. In the same way as these wild mammals act as reservoir and spread the fungus in the natural environment, infection in urban bats could well be associated with the increase in histoplasmosis clinical cases among immunosuppressed hosts in Buenos Aires city.