SUMMARYThis work presents the results of the detection of antibodies (immunoglobulin G) for subtypes I and VI of VEE viruses complex (Togaviridae family) in people from the General Belgrano island, Formosa province (Argentina). The prevalence of neutralizing (NT) antibodies for subtype VI was from 30% to 70% and the prevalence of antibodies inhibitory of hemagglutination (HI) was of 0% in the first and second inquiry respectively. For the subtype IAB the prevalence of NT antibodies was from 13% to 3.6%, similar to the prevalence total for both subtypes. HI antibodies were not detected in any inquiries for any subtype. It was observed that both subtypes circulate simultaneously, while subtype VI remains constant with some peaks, subtype I was found in low level.

This study was undertaken to establish the function of T-lymphocytes in protective immunity against a cryptococcal infection in animals treated with Cyclophosphamide (Cy) pre or post infection and to determine how they relate to the progression of the disease. Inbred Suquia rats were infected either intranasally (i.n.) or intraperitoneally (i.p.) with 10(5) viable Cryptococcus neoformans cells. The infected rats were divided in three groups. One of the groups (group I) was utilized as a control. The second group (group II) was treated with Cy 3 days before the infection. The third group (group III) was treated with Cy 3 days after the infection. At approximately 22 days post infection, C. neoformans growth in selected organs of all animals were determined. In addition, humoral and delayed-type hypersensitivity (DTH) response were assayed in the rats. When the Cy was applied after the infection the DTH was significantly diminished and inverse to the colony forming unit (CFU) which increased leading to the animals death. On the other hand, injection of the drug 3 days before infection did not modify the response, that was comparable in both treated and the control animals. In this study it were found haemagglutinating antibodies in sera from i.n. and i.p. infected rats although at minimal levels and were not present in all animals. The results show that with a low T-cell function induced as a consequence of injecting Cy after the infection, rats did not develop a normal DTH response to cryptococcal infections and were not able to control a cryptococcal infection as well as animals with normal T-cell function.

Objective: This study assessed the efficacy of nebulization (NEB), also known as fogging, to expose gilts to Mycoplasma hyopneumoniae under field conditions as a potential acclimation strategy. Materials and methods: Phase I consisted of 448 M hyopneumoniae-free gilts from four different batches of a gilt development unit (GDU). On study day 0, batches 1 and 2 were exposed to M hyopneumoniae-positive lung homogenate via intratracheal (IT) route and were used as reference for batches 3 and 4, which were exposed using a mechanical fogger. Tracheobronchial swabs (TBS) were collected at 2 and 4 weeks post exposure (D14 and D28, respectively) and infection success was assessed by real-time polymerase chain reaction of pooled samples. In phase II, 1160 gilts from the same GDU belonging to three different batches (5 to 7) were exposed to M hyopneumoniae via NEB, and TBS were collected at D14. Results: In phase I, no statistically significant differences were observed between IT and NEB exposure in proportion of positives and mean cycle threshold values of TBS pooled samples at any time point (D14 and D28). In phase II, TBS pooled samples from all batches were positive for M hyopneumoniae at D14. Implications: Nebulization of lung homogenate positive for M hyopneumoniae resulted in infection of commercial gilts with this pathogen. Therefore, the use of NEB may be a reliable M hyopneumoniae exposure method under field conditions. The information generated in this investigation broadens the understanding of this technology as an acclimation strategy.