Study of the host specificity of PB1-F2-associated virulence.

Influenza A viruses cause important diseases in both human and animal. The PB1-F2 protein is a virulence factor expressed by some influenza viruses. Its deleterious action for the infected host is mostly described in mammals, while the available information is scarce in avian hosts. In this work, we compared the effects of PB1-F2 in avian and mammalian hosts by taking advantage of the zoonotic capabilities of an avian H7N1 virus. In vitro, the H7N1 virus did not behave differently when PB1-F2 was deficient while a H3N2 virus devoid of PB1-F2 was clearly less inflammatory. Likewise, when performing in vivo challenges of either chickens or embryonated eggs, with the wild-type or the PB1-F2 deficient virus, no difference could be observed in terms of mortality, host response or tropism. PB1-F2 therefore does not appear to play a major role as a virulence factor in the avian host. However, when infecting NF-κB-luciferase reporter mice with the H7N1 viruses, a massive PB1-F2-dependent inflammation was quantified, highlighting the host specificity of PB1-F2 virulence. Surprisingly, a chimeric 7:1 H3N2 virus harboring an H7N1-origin segment 2 (i.e. expressing the avian PB1-F2) induced a milder inflammatory response than its PB1-F2-deficient counterpart. This result shows that the pro-inflammatory activity of PB1-F2 is governed by complex mechanisms involving components from both the virus and its infected host. Thus, a mere exchange of segment 2 between strains is not sufficient to transmit the deleterious character of PB1-F2.

Infection rate by TOXOPLASMA GONDII in free-range and broiler chickens in the states of Rio Grande do Norte and Paraíba, Brazil

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, a protozoan that has a cosmopolitan geographic distribution and low specificity for intermediate hosts. Domestic chickens are among the most important hosts in toxoplasmosis epidemiology, since they are potential sources of infection for humans, in addition to indicating environmental contamination by protozoa. In this work, we studied the prevalence of T. gondii infection in chickens in different breeding systems from distinct mesoregions of Rio Grande do Norte and Paraiba States: broiler chickens from commercial farms and free-range chickens from small farms. Indirect fluorescent antibody test (IFAT) and ELISA techniques were used for detecting specific antibodies in blood samples from the birds. There were no seropositive samples among the broilers tested, indicating that intensive management limited the chances of infection for these animals. Among the free-range chickens, the frequency of IgG anti-T. gondii detected by IFAT and ELISA were 37.9% and 40.4% respectively. Among the seropositive samples by IFAT, 33 (27.1%) were positive at a dilution of 1:16; in 1:32, 31 (25.4%); in 1:64, 24 (19.7%); 15 (12.3%) in 1:128, and 19 presented titers greater than or equal to 1:256 (15.6%). The substantial concordance observed between IFAT and ELISA signifies these methods are effective methodologies for the diagnosis of avian toxoplasmosis. The high prevalence of specific antibodies among poultry in the studied region highlights the potential risk of T. gondii transmission to humans through consumption of infected meat.

Rapid Determination of Benzylpenicillin Resistance in Staphylococcus aureus Bacteraemia Model.

Rapid determination of antimicrobial susceptibility/resistance is an important factor in selecting an appropriate antimicrobial treatment and eradicating infections promptly. Conventional antimicrobial susceptibility tests (ASTs) are very time consuming. Thus, we developed a liquid chromatography-mass spectrometry (LC-MS/MS) method for rapidly determining the resistance of Staphylococcus aureus to penicillin-G in an animal-infection model. This technique will be able to detect those resistant strains whose resistance mechanism specifically controlled by penicillinase. The resistance status of S. aureus against penicillin-G was determined by conventional AST. Cultured S. aureus cells were inoculated to chicken for developing bacteraemia. The solution of penicillin-G was intravenously administered (10 mg/kg b.w.) to chickens just after infection detection. Blood samples were collected at different intervals after drug administration. The concentration of active penicillin-G and its metabolites were determined from the bacteria-free blood supernatant by utilizing the LC-MS/MS method. Evidence of infection in chicken was observed within 5 h of bacterial inoculation. The penicillinase enzyme generated by S. aureus transforms the active penicillin-G to an inactive metabolite by hydrolysis, which is evident by the mass shift from 335.10600 to 353.11579 Da as quantified using liquid chromatography quadrupole time-of-flight mass spectrometry (LC/Q-TOF/MS). The signal intensity of inactive/hydrolysed penicillin-G is several-fold greater than that of the active penicillin-G in the blood sample of chicken infected with resistant strain and treated with penicillin-G. The antimicrobial resistance index (ARI) value of resistant S. aureus strain was more than 1, demonstrating the penicillin-G-resistance pattern of that strain. This method is able to determine the extent of ß-lactam antimicrobial resistance within 1.5 h from the patient's blood and is complementary with those existing AST methods which are usually practicing in the evaluation of ß-lactam antibiotic resistance.

The blaNDM-1-Carrying IncA/C2 Plasmid Underlies Structural Alterations and Cointegrate Formation In Vivo.

In 2012, a carbapenemase-producing Salmonella enterica serovar Corvallis isolate carrying a blaNDM-1 multiresistance IncA/C2 plasmid, apart from IncHI2 and ColE-like plasmids, was detected in a wild bird in Germany. In a recent broiler chicken infection study, we observed transfer of this blaNDM-1-carrying IncA/C2 plasmid to other Enterobacteriaceae Here, we focused on the stability of this plasmid and gained insight into the type and frequency of its structural alterations after an in vivo passage in a broiler chicken infection study.