Tiller density and tillering on Brachiaria brizantha cv. Marandu pastures inoculated with Azospirillum brasilense / Densidade populacional e perfilhamento em pastagens de Brachiaria brizantha cv. Marandu inoculada com Azospirillum brasilense

The objective of this study is to verify the population density and the dynamics of tillering in the Marandu palisade grass sward subjected to nitrogen (N) fertilization strategies, characterized by the N supply via urea or bacterial inoculant (Azospirillum brasilense). The treatments comprised of four nitrogen fertilization strategies: (A) Without fertilization, (B) 80 kg N/ha, (C) inoculant (A. brasilense), and (D) 80 kg N/ha + inoculant, distributed in a randomized complete block design, with three replications. The nitrogen supply strategies were evaluated during six periods: October, November, and December (2012) as well as January, March, and April (2013). The nitrogen dose or inoculant had no effect on the tiller appearance rate (TAR), tiller mortality rate (TMR), tiller survival rate (TSR), or tiller population density (TPD). However, these variables were influenced by the season. The TAR and TSR were higher at the beginning of the experimental period (October) and lower towards the end of the period (March-April), whereas, TMR and TPD exhibited the opposite behavior, with lower values in October and higher from January onward. Neither the nitrogen nor the inoculant influenced the population dynamics of the tillers in Marandu palisade grass.(AU)

Objetivou-se com este estudo verificar a densidade populacional e a dinâmica do perfilhamento em dosséis de capim Marandu submetidos a estratégias de adubação nitrogenada, caracterizadas pelo fornecimento de N via ureia ou inoculante (Azospirillum brasilense). Os tratamentos foram quatro estratégias de adubação nitrogenada: sem fertilização, 80kg N/ha, inoculante (A. brasilense) e 80kg N/ha + inoculante, distribuídos em um delineamento de blocos completos ao acaso, com três repetições por tratamento. As estratégias de aporte nitrogenado foram avaliadas em seis épocas: outubro, novembro e dezembro de 2012; e janeiro, março e abril de 2013. Não foi verificada influência da dose de nitrogênio ou do inoculante sobre a taxa de aparecimento (TAP), a taxa de mortalidade (TMP), a taxa de sobrevivência (TSP) e a densidade populacional de perfilhos (DPP). No entanto, essas variáveis foram influenciadas pela época do ano. A TAP e a TSP apresentaram maiores valores no início do período experimental (outubro) e menor valor ao final do período (março a abril). A TMP e a DPP expressaram respostas opostas, com menores valores em outubro e maiores a partir de janeiro. Não houve influência do nitrogênio e do inoculante sobre a dinâmica populacional de perfilhos em capim Marandu.(AU)

Pinhal virus, a new arenavirus isolated from calomys tener in Brazil

Arenavirus Sabiá was originally isolated from a fatal human infection in Brazil, and after the occurrence of the second fatal human case in São Paulo state, epidemiologic and virologic studies were performed in the area where the patient lived, aiming at the identification of the Sabiá natural rodent reservoir. A broadly cross-reactive enzyme-linked immunosorbent assay (ELISA) was used to screen for antibody-positive samples. Antibodies to arenavirus were detected in two of the 55 samples of Calomys tener, and from these results, samples of rodents were analyzed by a broad RT-PCR assay. RT-PCR amplification detected arenavirus sequences in five of the 55 C. tener samples, and sequencing showed that this virus is a distinct form of Sabiá virus. Thus, we describe here the evidence for the circulation of a new arenavirus in Brazil (proposed name Pinhal virus) and its genetic characterization compared to other arenaviruses. This study also suggests C. tener as a probable rodent reservoir for this virus and associates this new virus with the lineage C of New World arenaviruses. Although we have defined some characteristics of this virus, so far, there is no evidence of its involvement in human disease.

Preliminary in vivo efficacy studies of a recombinant rhesus anti-alpha(4)beta(7) monoclonal antibody.

Recent findings established that primary targets of HIV/SIV are lymphoid cells within the gastrointestinal (GI) tract. Focus has therefore shifted to T-cells expressing alpha(4)beta(7) integrin which facilitates trafficking to the GI tract via binding to MAdCAM-1. Approaches to better understand the role of alpha(4)beta(7)+ T-cells in HIV/SIV pathogenesis include their depletion or blockade of their synthesis, binding and/or homing capabilities in vivo. Such studies can ideally be conducted in rhesus macaques (RM), the non-human primate model of AIDS. Characterization of alpha(4)beta(7) expression on cell lineages in RM blood and GI tissues reveal low densities of expression by NK cells, B-cells, naïve and TEM (effector memory) T-cells. High densities were observed on TCM (central memory) T-cells. Intravenous administration of a single 50mg/kg dose of recombinant rhesus alpha(4)beta(7) antibody resulted in significant initial decline of alpha(4)beta(7)+ lymphocytes and sustained coating of the alpha(4)beta(7) receptor in both the periphery and GI tissues.

Sooty mangabeys and rhesus macaques exhibit significant divergent natural killer cell responses during both acute and chronic phases of SIV infection.

A correlation between NK cells and rate of disease progression in HIV-1-infected individuals has been documented. The role NK cells play in disease outcome can optimally be studied in SIV-infected disease susceptible rhesus macaques (RM) and SIV-infected disease resistant sooty mangabeys (SM). In this study, three main subsets of CD16(+)CD56(-), CD16(-/dim)CD56(+) and CD16(-)CD56(-) NK cells have been identified with the predominant CD16(+)CD56(-) subset being primarily responsible for cytolytic activity in both species. Cross-sectional studies revealed a significant decline in the frequency and function of this cytolytic subset in SIV-infected RM while an increase occurred in SIV-infected SM. Longitudinal studies revealed that an earlier NK response during acute infection occurred in all SIV-infected SM and in select SIV-infected RM that eventually controlled viral load set point during chronic infection, suggesting that early NK activity and continued maintenance of this cell lineage may indirectly contribute to disease resistance.

Pharmacokinetics, toxicity, and functional studies of the selective Kv1.3 channel blocker 5-(4-phenoxybutoxy)psoralen in rhesus macaques.

The small molecule 5-(4-phenoxybutoxy)psoralen (PAP-1) is a selective blocker of the voltage-gated potassium channel Kv1.3 that is highly expressed in cell membranes of activated effector memory T cells (TEMs). The blockade of Kv1.3 results in membrane depolarization and inhibition of TEM proliferation and function. In this study, the in vitro effects of PAP-1 on T cells and the in vivo toxicity and pharmacokinetics (PK) were examined in rhesus macaques (RM) with the ultimate aim of utilizing PAP-1 to define the role of TEMs in RM infected with simian immunodeficiency virus (SIV). Electrophysiologic studies on T cells in RM revealed a Kv1.3 expression pattern similar to that in human T cells. Thus, PAP-1 effectively suppressed TEM proliferation in RM. When administered intravenously, PAP-1 showed a half-life of 6.4 hrs; the volume of distribution suggested extensive distribution into extravascular compartments. When orally administered, PAP-1 was efficiently absorbed. Plasma concentrations in RM undergoing a 30-day, chronic dosing study indicated that PAP-1 levels suppressive to TEMs in vitro can be achieved and maintained in vivo at a non-toxic dose. PAP-1 selectively inhibited the TEM function in vivo, as indicated by a modest reactivation of cytomegalovirus (CMV) replication. Immunization of these chronically treated RM with the live influenza A/PR8 (flu) virus suggested that the development of an in vivo, flu-specific, central memory response was unaffected by PAP-1. These RM remained disease-free during the entire course of the PAP-1 study. Collectively, these data provide a rational basis for future studies with PAP-1 in SIV-infected RM.

Simian immunodeficiency virus (SIV) infection influences the level and function of regulatory T cells in SIV-infected rhesus macaques but not SIV-infected sooty mangabeys.

Differences in clinical outcome of simian immunodeficiency virus (SIV) infection in disease-resistant African sooty mangabeys (SM) and disease-susceptible Asian rhesus macaques (RM) prompted us to examine the role of regulatory T cells (Tregs) in these two animal models. Results from a cross-sectional study revealed maintenance of the frequency and absolute number of peripheral Tregs in chronically SIV-infected SM while a significant loss occurred in chronically SIV-infected RM compared to uninfected animals. A longitudinal study of experimentally SIV-infected animals revealed a transient increase in the frequency of Tregs from baseline values following acute infection in RM, but no change in the frequency of Tregs occurred in SM during this period. Further examination revealed a strong correlation between plasma viral load (VL) and the level of Tregs in SIV-infected RM but not SM. A correlation was also noted in SIV-infected RM that control VL spontaneously or in response to antiretroviral chemotherapy. In addition, immunofluorescent cell count assays showed that while Treg-depleted peripheral blood mononuclear cells from RM led to a significant enhancement of CD4+ and CD8+ T-cell responses to select pools of SIV peptides, there was no detectable T-cell response to the same pool of SIV peptides in Treg-depleted cells from SIV-infected SM. Our data collectively suggest that while Tregs do appear to play a role in the control of viremia and the magnitude of the SIV-specific immune response in RM, their role in disease resistance in SM remains unclear.

[Ilheus arbovirus in wild birds (Sporophila caerulescens and Molothrus bonariensis)]. / Arbovírus Ilheus em aves silvestres (Sporophila caerulescens e Molothrus bonariensis).

OBJECTIVE: To report the first Ilheus arboviruses isolated from wild birds and analyze its public health impact. METHODS: Wild birds and mammals were captured using mist nets and Tomahawk traps, respectively. Blood samples were drawn from these animals and inoculated intracerebrally in Swiss suckling mice found in the Parque Ecológico do Tietê, Brazil. The isolates were identified by serological tests, such as hemagglutination, hemagglutination inhibition, complement fixation and neutralization. Besides virus isolation, serum samples were also tested for the presence of hemagglutination inhibition antibodies. RESULTS: Two strains of Ilheus virus were isolated from the bird species Sporophila caerulescens and Molothrus bonariensis. Specific antibodies to Ilheus virus were detected in serum samples of some birds (Columbina talpacoti, Geopelia cuneata, Sicalis flaveola and Molothrus bonariensis), marmosets (Callithrix jacchus and Callithrix penicillata) and coati (Nasua nasua). CONCLUSIONS: Virus isolation and detection of specific antibodies in serum samples of local, migratory and captive birds, captive marmosets and wild coati corroborate the circulation of Ilheus virus in the Parque Ecológico do Tietê. The migrating behavior of some species of wild birds, like Sporophila caerulescens, enables the virus spread to other regions. Taking into consideration its human pathogenicity and the presence of the virus in this area, local authorities should be aware of the risk of infecting the local community.

Hantavirus pulmonary syndrome in the State of São Paulo, Brazil, 1993-1998.

Between 1993 and 1998, 10 cases of clinical hantavirus infection were diagnosed in Brazil. Hantavirus-specific IgM, or positive immunohistochemical analysis for hantavirus antigen, or positive reverse transcription-polymerase chain reaction results for hantavirus RNA were used to confirm nine of these cases; eight were hantavirus pulmonary syndrome (HPS), and one was mild hantavirus disease. The remaining clinical case of hantavirus infection was fatal, and no tissue was available to confirm the diagnosis. During the first 7 months of 1998, five fatal HPS cases caused by a Sin Nombre-like virus were reported from three different regions in the State of São Paulo, Brazil: two in March (Presidente Prudente Region), two in May (Ribeirão Preto Region), and one in July (Itapecerica da Serra Region). Epidemiologic, ecologic, and serologic surveys were conducted among case contacts, area residents, and captured rodents in five locations within the State of São Paulo in June of 1998. Six (4.8%) of 125 case contacts and six (5.2%) of 116 area residents had IgG antibody to Sin Nombre virus (SNV) antigen. No case contacts had a history of HPS-compatible illness, and only one area resident reported a previous acute respiratory illness. A total of 403 rodents were captured during 9 nights of trapping (1969 trap nights). All 27 rodents that were found to be positive for IgG antibody to SNV antigen were captured in crop border and extensively deforested agricultural areas where four of the 1998 HPS case-patients had recently worked. The IgG antibody prevalence data for rodents suggest that Bolomys lasiurus and perhaps Akodon sp. are potential hantavirus reservoirs in this state of Brazil.

Genetic investigation of novel hantaviruses causing fatal HPS in Brazil.

Although hantavirus pulmonary syndrome (HPS) was discovered in North America in 1993, more recent investigations have shown that the disease is a much larger problem in South America, where a greater number of cases and HPS-associated viruses have now been detected. Here we describe the genetic investigation of three fatal HPS cases from Brazil, including a 1995 case in Castelo dos Sonhos (CAS) in the state of Mato Grosso and two 1996 cases in the counties of Araraquara (ARA) and Franca (FRA), in the state of São Paulo. Reverse transcription-polymerase chain reaction (RT-PCR) products representing fragments of the hantavirus N, G1, and G2 coding regions were amplified from patient acute-phase serum samples, and the nucleotide (nt) sequences (394, 259, and 139 nt, respectively) revealed high deduced amino acid sequence identity between ARA and FRA viruses (99.2%, 96.5%, and 100%, respectively). However, amino acid differences of up to 14.0% were observed when ARA and FRA virus sequences were compared with those of the geographically more distant CAS virus. Analysis of a 643-nt N coding region and a 1734-nt predominantly G2-encoding region of ARA and CAS virus genomes confirmed that these Brazilian viruses were distinct and monophyletic with previously characterized Argentinean hantaviruses, and suggested that Laguna Negra (LN) virus from Paraguay was ancestral to both the Brazilian and Argentinean viruses. The phylogenetic tree based on the N coding fragment also placed LN in a separate clade with Rio Mamore virus from Bolivia. At the amino acid level, ARA and CAS viruses appeared more closely related to the Argentinean viruses than they were to each other. Similarly, analysis of the diagnostic 139-nt G2 fragment showed that the Juquitiba virus detected in a 1993 fatal HPS case close to São Paulo city, Brazil was closer to Argentinean viruses than to ARA or CAS viruses. These data indicate that at least three different hantavirus genetic lineages are associated with Brazilian HPS cases.

Retinoic acid stimulates the expression of 11beta-hydroxysteroid dehydrogenase type 2 in human choriocarcinoma JEG-3 cells.

The syncytiotrophoblasts of the human placenta express high levels of 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the enzyme responsible for the inactivation of glucocorticoids. It has been proposed that the placental 11beta-HSD2 serves as a barrier to protect the fetus from high levels of maternal cortisol. To examine the hypothesis that nutritional signals regulate the expression of 11beta-HSD2 in placental syncytiotrophoblasts, we investigated the effects of retinoic acids (RAs), the major metabolites of vitamin A, on the expression of 11beta-HSD2 using human choriocarcinoma JEG-3 cells as a model. This trophoblast-like cell line displays a number of functional similarities to the syncytiotrophoblast. Treatment for 24 h with all-trans RA (1-1000 nM) resulted in a dose-dependent increase in 11beta-HSD2 activity with a maximal effect (increase to 3-fold) at 100 nM. The effect of all-trans RA (100 nM) was also time-dependent in that the effect was detectable at 6 h and reached its maximum by 48 h. Similar increases in 11beta-HSD2 activity were observed when the cells were treated with 9-cis RA. Results from semi-quantitative reverse transcription-polymerase chain reaction demonstrated that there was a corresponding increase in 11beta-HSD2 mRNA after RA treatment. Moreover, treatment with actinomycin D (100 ng/ml) abrogated the increase in 11beta-HSD2 mRNA induced by RA, indicating an effect on transcription. In conclusion, the present study has demonstrated for the first time that RA, at physiological concentrations, induces 11beta-HSD2 gene expression and enzyme activity in JEG-3 cells. If this occurs in vivo, the present finding suggests that high expression of 11beta-HSD2 in the human placenta may be maintained, at least in part, by dietary intake of vitamin A.

Report on ticks collected in the Southeast and Mid-West regions of Brazil: analyzing the potential transmission of tick-borne pathogens to man.

Specimens of ticks were collected in 1993, 1996, 1997, and 1998, mostly from wild and domestic animals in the Southeast and Mid-West regions of Brazil. Nine species of Amblyommidae were identified: Anocentor nitens, Amblyomma cajennense, Amblyomma ovale, Amblyomma fulvum, Amblyomma striatum, Amblyomma rotundatum, Boophilus microplus, Boophilus annulatus, and Rhipicephalus sanguineus. The potential of these tick species as transmitters of pathogens to man was analyzed. A Flaviviridade Flavivirus was isolated from Amblyomma cajennense specimens collected from a sick capybara (Hydrochaeris hydrochaeris). Amblyomma cajennense is the main transmitter of Rickettsia rickettsii (=R. rickettsi), the causative agent of spotted fever in Brazil. Wild mammals, mainly capybaras and deer, infested by ticks and living in close contact with cattle, horses and dogs, offer the risk of transmission of wild zoonosis to these domestic animals and to man.

Human disease caused by an arbovirus closely related to Ilheus virus: report of five cases.

We report five cases of human disease caused by arbovirus in 5 patients from the State of São Paulo, Brazil, residing in the municipalities of Osasco, Atibaia, Guarujá, and the capital São Paulo, respectively. One of the patients resides in São Luis, capital of the State of Maranhão. The sites of infection probably were the states of Paraná and Goiás, both in cave regions, the State of Amazonas, and Rondônia in two cases. Laboratory tests for malaria were negative and 1 patient showed a positive serum reaction for leptospirosis. Serum samples from the acute and convalescent phases were tested by hemagglutination inhibition, complement fixation, and neutralization in mice. Acute phase samples were inoculated into suckling mice by the intracerebral route. A close antigenic relationship was observed between the five agents isolated and the flavivirus Ilheus. Serologic tests demonstrated the absence of antibodies in all samples from the 5 patients during convalescence and even for more than 1 year after infection in 1 of them.

Surveillance of arbovirus infections in the Atlantic Forest Region, State of São Paulo, Brazil. I. Detection of hemagglutination-inhibiting antibodies in wild birds between 1978 and 1990.

We report data related to arbovirus antibodies detected in wild birds periodically captured from January 1978 to December 1990 in the counties of Salesópolis (Casa Grande Station), Itapetininga and Ribeira Valley, considering the different capture environments. Plasmas were examined using hemagglutination-inhibition (HI) tests. Only monotypic reactions were considered, except for two heterotypic reactions in which a significant difference in titer was observed for a determined virus of the same antigenic group. Among a total of 39,911 birds, 269 birds (0.7%) belonging to 66 species and 22 families were found to have a monotypic reaction for Eastern equine encephalitis (EEE), Venezuelan equine encephalitis (VEE), Western equine encephalitis (WEE), Ilheus (ILH), Rocio (ROC), St. Louis encephalitis (SLE), SP An 71686, or Caraparu (CAR) viruses. Analysis of the data provided information of epidemiologic interest with respect to these agents. Birds with positive serology were distributed among different habitats, with a predominance of unforested habitats. The greatest diversity of positive reactions was observed among species which concentrate in culture fields.

Iguape: a newly recognized flavivirus from São Paulo State, Brazil.

A new virus, SP An 71686, was isolated from sentinel mice exposed in a forest area in Iguape county, São Paulo state, Brazil, in 1979. The results suggest [hemagglutination inhibition (HI), complement fixation, neutralization, and ELISA] that SP An 71686 virus is a new arbovirus and that it demonstrates some cross-reactivity with other members of the family Flaviviridae, but can be differentiated from them. Although there is an intensive circulation of several arboviruses in the area, the only diagnosed cases of human disease were caused by Rocio virus during and after the epidemic of encephalitis that occurred in 1975-1977, one case of febrile illness by Caraparu virus in 1983, and by subtype IF of Venezuelan equine encephalitis virus in soldiers during jungle survival training in 1990. Wild animals had a prevalence of SP An 71686 HI monotype antibodies: 46% of birds captured in 1990, 40% in 1991 and 19.5% in 1992. These results suggested that wild birds may play a role in the virus transmission cycle. Mammals (rodents and marsupials) must also be considered potential hosts. However, the virus reservoir-vector relationships need further studies which would help to clarify the ecology of this virus.

Isolation of St. Louis encephalitis virus in South Brazil.

Eight strains of a flavivirus identified as St. Louis encephalitis (SLE) virus were isolated from wild rodents, birds, and sentinel mice in three locations in the State of São Paulo, Brazil from 1967--1969. No illness attributable to SLE virus infection was detected among the local inhabitants, although about 5% of the local population had neutralizing antibodies to this virus.