Rickettsia monteiroi sp. nov., infecting the tick Amblyomma incisum in Brazil.

Free-living adult Amblyomma incisum ticks were collected in an Atlantic rainforest area at Intervales State Park, State of São Paulo, Brazil. From an A. incisum specimen, rickettsiae were successfully isolated in Vero cell culture by the shell vial technique. Rickettsial isolation was confirmed by optical microscopy, transmission electron microscopy, and PCRs targeting portions of the rickettsial genes gltA, htrA, rrs, and sca1 on infected cells. Fragments of 1,089, 457, 1,362, and 443 nucleotides of the gltA, htrA, rrs, and sca1 genes, respectively, were sequenced. By BLAST analysis, the partial sequence of rrs of the A. incisum rickettsial isolate was closest to the corresponding sequence of Rickettsia bellii (99.1% similarity). The gltA partial sequence was closest to the corresponding sequences of "Candidatus Rickettsia tarasevichiae" (96.1% similarity) and Rickettsia canadensis (95.8% similarity). The htrA partial sequence was closest to the corresponding sequence of R. canadensis (89.8% similarity). The sca1 partial sequence was closest to the corresponding sequence of R. canadensis (95.2% similarity). Since our rickettsial isolate was genetically distinct from other Rickettsia species, we propose a new species designated Rickettsia monteiroi sp. nov. Phylogenetic analyses indicated that R. monteiroi belongs to the canadensis group within the genus Rickettsia, together with the species R. canadensis and "Candidatus R. tarasevichiae". Little or no antibody cross-reaction was observed between sera of R. monteiroi-inoculated guinea pigs and R. bellii-, Rickettsia rickettsii-, or R. canadensis-inoculated guinea pigs.

Mass mortality associated with a frog virus 3-like Ranavirus infection in farmed tadpoles Rana catesbeiana from Brazil.

Ranaviruses (Iridoviridae) are increasingly associated with mortality events in amphibians, fish, and reptiles. They have been recently associated with mass mortality events in Brazilian farmed tadpoles of the American bullfrog Rana catesbeiana Shaw, 1802. The objectives of the present study were to further characterize the virus isolated from sick R. catesbeiana tadpoles and confirm the etiology in these outbreaks. Sick tadpoles were collected in 3 farms located in Goiás State, Brazil, from 2003 to 2005 and processed for virus isolation and characterization, microbiology, histopathology, and parasitology. The phylogenetic relationships of Rana catesbeiana ranavirus (RCV-BR) with other genus members was investigated by PCR with primers specific for the major capsid protein gene (MCP) and the RNA polymerase DNA-dependent gene (Pol II). Sequence analysis and multiple alignments for MCP products showed >99% amino acid identity with other ranaviruses, while Pol II products showed 100% identity. Further diagnostics of the pathology including histology and transmission electron microscopy confirmed the viral etiology of these mass deaths. As far as we know, this is the first report of a ranaviral infection affecting aquatic organisms in Brazil. Additionally, our results suggest that American bullfrogs may have served as a vector of transmission of this virus, which highlights the potential threat of amphibian translocation in the world distribution of pathogens.

Isolation and genome characterization of canine parvovirus type 2c in Brazil.

This study focused on the isolation and characterization of parvovirus in an infected dog in midwestern Brazil. Non-enveloped icosahedral parvovirus-like particles were isolated in CRFK cells and were allocated to a clade comprised of strains of CPV-2c, based on genome analysis. This is the first isolate of CPV-2c genomically characterized in Brazil.

Isolation of avian nephritis virus from chickens showing enteric disorders.

Runting-stunting syndrome (RSS) is one of the diseases associated with many detected viruses. In Brazil, there were reports of several enteric disease outbreaks in chickens in which avian nephritis virus (ANV) was detected; however, the role of ANV in the outbreaks and whether the virus was a causative agent of these cases of enteric diseases were not determined. The aim of this study was to isolate ANV in specific pathogen-free (SPF) chicken embryonated eggs (CEE) from the enteric contents of chickens showing signs of RSS. For this purpose, 22 samples of chicken enteric contents that were positive only for ANV were inoculated into 7 and 14-day-old SPF-CEE via the yolk sac route and incubated for 5 d, with a total of 3 passages. Virus isolation was confirmed by the presence of embryo injuries, detection of viral RNA by RT-PCR, and visualization of viral particles using electron microscopy. Therefore, the 7-day-old inoculated embryos showed dwarfism, gelatinous consistency, hemorrhage, and edema in the embryos, whereas the 14-day-old did not show any alteration. Viral RNA was detected in the embryos of both ages of inoculation, and the same viral particles were visualized. The embryos from the mock group showed no alteration and were negative for all the tests. The viral cDNA was sequenced, and the molecular and phylogenetic analyses showed that the Brazilian isolates are more related with the ANV-1 serotype group; the sequences of these isolates showed a high percentage of nucleotide (86.4 to 94.9%) and amino acid (92.3 to 98.7%) similarity with other sequences from China, Japan, Australia, and the United States that belong to this serotype previously classified group. In this study, we isolated 8 samples of ANV in SPF-CEE from enteric content samples from chickens with RSS. In doing so, we showed the pathological injuries to the embryo caused by the virus and the molecular characterization of a part of the ORF 1b gene of the virus.

Case-control study of pathogens involved in piglet diarrhea.

BACKGROUND: Diarrhea in piglets directly affects commercial swine production. The disease results from the interaction of pathogens with the host immune system and is also affected by management procedures. Several pathogenic agents such as Campylobacter spp., Clostridium perfringens, Escherichia coli, Salmonella spp., group A rotavirus (RV-A), coronaviruses (transmissible gastroenteritis virus; porcine epidemic diarrhea virus), as well as nematode and protozoan parasites, can be associated with disease cases. RESULTS: All bacterial, viral, protozoan, and parasitic agents here investigated, with the exception of Salmonella spp. as well as both coronaviruses, were detected in varying proportions in piglet fecal samples, and positive animals were equally distributed between case and control groups. A statistically significant difference between case and control groups was found only for Cystoisospora suis (p = 0.034) and Eimeria spp. (p = 0.047). When co-infections were evaluated, a statistically significant difference was found only for C. perfringens ß2 and C. suis (p = 0.014). CONCLUSIONS: The presence of pathogens in piglets alone does not determine the occurrence of diarrhea episodes. Thus, the indiscriminate use of antibiotic and anthelminthic medication should be re-evaluated. This study also reinforces the importance of laboratory diagnosis and correct interpretation of results as well as the relevance of control and prophylactic measures.