The Role of Ethylene Production in Virulence of Pseudomonas syringae pvs. glycinea and phaseolicola

ABSTRACT The importance of ethylene production for virulence of Pseudomonas syringae pvs. glycinea and phaseolicola was assayed by comparing bacterial multiplication and symptom development in bean and soybean plants inoculated with ethylene-negative (efe) mutants and wild-type strains. The efe mutants of Pseudomonas syringae pv. glycinea were significantly reduced in their ability to grow in planta. However, the degree of reduction was strain-dependent. Population sizes of efe mutant 16/83-E1 that did not produce the phototoxin coronatine were 10- and 15-fold lower than those of the wild-type strain on soybean and on bean, and 16/83-E1 produced very weak symptoms compared with the wild-type strain. The coronatine-producing efe mutant 7a/90-E1 reached fourfold and twofold lower population sizes compared with the wild-type strain on soybean and bean, respectively, and caused disease symptoms typical of the wild-type strain. Experiments with ethylene-insensitive soybeans confirmed these results. The virulence of the wild-type strains was reduced to the same extent in ethylene-insensitive soybean plants as the virulence of the efe mutants in ethylene-susceptible soybeans. In contrast, the virulence of Pseudomonas syringae pv. phaseolicola was not affected by disruption of the efe gene.     

The humeral immune response of swine after experimental infection with Salmonella typhimurium

LPS antibody reaction of S. Typhimurium was detected in a total of 111 two- to ten-week-old pigs, which had been exposed to experimental oral infection with this serovar in 16 separate experiments. The total antibody level was determined according to the meat juice ELISA provided for the Salmonella control programme and the antibody concentrations of the isotopes IgG1, IgG2, IgA and IgM. Although there were significant differences between the individual experiments with respect to the reaction intensity and proportion of the individual immune globulin isotypes, the following general statements on the dynamics of the antibody reaction can be made: Clearly elevated antibody levels could be observed one week after the onset of infection. After one and two weeks, respectively, 22.5 and 52.9% of the infected animals showed antibody levels which were to be evaluated as positive in the sense of the Salmonella control programme (> or = 40%). While the concentration of the IgM-related antibodies decreased again during the second week already, the antibody concentration of IgG1 and IgG2 continued to increase until the end of the experiment after 3 weeks. The clear differences in the reactions between the experiments cannot be explained solely by defined conditions of infection such as strain of infection, infective dose or age of the pigs. Obviously, other non-defined or non-recognized factors may have a decisive influence on the dynamics of the antibody reaction in the animal groups.     

Usefulness of serological examinations in the analysis of Salmonella infections in pig herds

The development of the antibody concentration against lipopolysaccharide (LPS) of S. Typhimurium und S. Choleraesuis in rearing pigs during the fattening period and in breeding sows of the corresponding age was recorded. The studies revealed the following results. Antibodies of isotypes IgG1 and IgG2 revealed a more pronounced specificity against the according Salmonella serovar than IgM antibodies. The calculated "antibody percent value" based on the total amount of Salmonella antibodies is mainly determined by the IgM antibodies in sera and meat juice, respectively. In fattening pigs a significant increase of antibodies against IgM and total Ig was observed between week 3 and 10 after beginning of the rearing period. In breeding pigs this increase was detectable already earlier. In only 3 out of 10 groups an increase of IgG1 and IgG2 was also seen. The detected significant increase of total Ig and IgM in the other groups might be the result of a less intensive exposure to salmonellas or it might be due to an increase of unspecific antibodies induced by other antigens. Serological investigations represent a valuable tool to record the intensity and development in time of the Salmonella exposure in pigs farms. Examination of total Ig is an appropriate method to detect pig herds with a high level of Salmonella exposure, for detailed epidemiological studies in pig farms the examination of antibody isotypes will give more comprehensive information.     

Safety and immunogenicity of a delta inulin-adjuvanted inactivated Japanese encephalitis virus vaccine in pregnant mares and foals

In 2011, following severe flooding in Eastern Australia, an unprecedented epidemic of equine encephalitis occurred in South-Eastern Australia, caused by Murray Valley encephalitis virus (MVEV) and a new variant strain of Kunjin virus, a subtype of West Nile virus (WNV_KUN). This prompted us to assess whether a delta inulin-adjuvanted, inactivated cell culture-derived Japanese encephalitis virus (JEV) vaccine (JE-ADVAX™) could be used in horses, including pregnant mares and foals, to not only induce immunity to JEV, but also elicit cross-protective antibodies against MVEV and WNV_KUN. Foals, 74–152 days old, received two injections of JE-ADVAX™. The vaccine was safe and well-tolerated and induced a strong JEV-neutralizing antibody response in all foals. MVEV and WNV_KUN antibody cross-reactivity was seen in 33% and 42% of the immunized foals, respectively. JE-ADVAX™ was also safe and well-tolerated in pregnant mares and induced high JEV-neutralizing titers. The neutralizing activity was passively transferred to their foals via colostrum. Foals that acquired passive immunity to JEV via maternal antibodies then were immunized with JE-ADVAX™ at 36–83 days of age, showed evidence of maternal antibody interference with low peak antibody titers post-immunization when compared to immunized foals of JEV-naïve dams. Nevertheless, when given a single JE-ADVAX™ booster immunization as yearlings, these animals developed a rapid and robust JEV-neutralizing antibody response, indicating that they were successfully primed to JEV when immunized as foals, despite the presence of maternal antibodies. Overall, JE-ADVAX™ appears safe and well-tolerated in pregnant mares and young foals and induces protective levels of JEV neutralizing antibodies with partial cross-neutralization of MVEV and WNV_KUN.     

Expression of Perilipin 2 (PLIN2) in Porcine Oocytes During Maturation

Perilipins have been reported to limit the interaction of lipases with neutral lipids within the droplets, thereby regulating neutral lipid accumulation and utilization. This study aimed to identify the location and expression of PLIN1 and PLIN2 in porcine oocytes during maturation. Quantitative real‐time polymerase chain reaction (qRT‐PCR), immunostaining and Western blot methods were used to characterize the expression and distribution patterns of PLIN1 and PLIN2 in porcine oocytes. The results showed that PLIN1 was not detectable in porcine oocytes. PLIN2 and BODIPY 493/503‐detected neutral lipid droplets appeared identical distribution patterns and extensive colocalization in both GV and MII porcine oocytes. PLIN2 protein expression was higher in GV oocytes than that in MII oocytes (p < 0.05), although PLIN2 mRNA expression was similar in both groups. These findings suggested that PLIN2 was a major lipid droplet‐associated protein in porcine oocytes.     

Dirofilaria immitis in cats from inner Sydney

Two hundred feral cats from the inner suburbs of Sydney were examined post mortem for adult Dirofilaria immitis and circulating microfilariae, and 101 of these cats were tested for heartworm antigens by an ELISA. Only 2 cats (1%) had adult heartworms, the blood sample from another cat contained a single microfilaria. The blood of a further three cats contained small amounts of D immitis antigen. Although D immitis occurs in cats in Sydney, the prevalence is not high enough to warrant prophylactic treatment.