Fusarium graminearum Schw. pasożyt wtórny na Uromyces fabae (Pers.) de Bary - Fusarium graminearum Schw. secondary parasite of Uromyces fabae (Pers.) de Bary

The work presents the description of <i>Fusarium praminearum</i> Schw. seconday parasite of <i>Uromyces fabae</i> (Pers.) de Bary occurring on the leves of <i>Vicia faba</i> L.

IL-27 Receptor Signaling Regulates Memory CD4+T Cell Populations and Suppresses Rapid Inflammatory Responses during Secondary Malaria Infection

ABSTRACTInterleukin-27 (IL-27) is known to control primary CD4+T cell responses during a variety of different infections, but its role in regulating memory CD4+T responses has not been investigated in any model. In this study, we have examined the functional importance of IL-27 receptor (IL-27R) signaling in regulating the formation and maintenance of memory CD4+T cells following malaria infection and in controlling their subsequent reactivation during secondary parasite challenge. We demonstrate that although the primary effector/memory CD4+T cell response was greater in IL-27R-deficient (WSX-1−/−) mice followingPlasmodium bergheiNK65 infection than in wild-type (WT) mice, there were no significant differences in the size of the maintained memory CD4+T population(s) at 20 weeks postinfection in the spleen, liver, or bone marrow of WSX-1−/−mice compared with WT mice. However, the composition of the memory CD4+T cell pool was slightly altered in WSX-1−/−mice following clearance of primary malaria infection, with elevated numbers of late effector memory CD4+T cells in the spleen and liver and increased production of IL-2 in the spleen. Crucially, WSX-1−/−mice displayed significantly enhanced parasite control compared with WT mice following rechallenge with homologous malaria parasites. Improved parasite control in WSX-1−/−mice during secondary infection was associated with elevated systemic production of multiple inflammatory innate and adaptive cytokines and extremely rapid proliferation of antigen-experienced T cells in the liver. These data are the first to demonstrate that IL-27R signaling plays a role in regulating the magnitude and quality of secondary immune responses during rechallenge infections.

BALB/c Mice Vaccinated withLeishmania majorRibosomal Proteins Extracts Combined with CpG Oligodeoxynucleotides Become Resistant to Disease Caused by a Secondary Parasite Challenge

Leishmaniasis is an increasing public health problem and effective vaccines are not currently available. We have previously demonstrated that vaccination with ribosomal proteins extracts administered in combination of CpG oligodeoxynucleotides protects susceptible BALB/c mice against primaryLeishmania majorinfection. Here, we evaluate the long-term immunity to secondary infection conferred by this vaccine. We show that vaccinated and infected BALB/c mice were able to control a secondaryLeishmania majorchallenge, since no inflammation and very low number of parasites were observed in the site of reinfection. In addition, although an increment in the parasite burden was observed in the draining lymph nodes of the primary site of infection we did not detected inflammatory lesions at that site. Resistance against reinfection correlated to a predominant Th1 response against parasite antigens. Thus, cell cultures established from spleens and the draining lymph node of the secondary site of infection produced high levels of parasite specific IFN-γin the absence of IL-4 and IL-10 cytokine production. In addition, reinfected mice showed a high IgG2a/IgG1 ratio for anti-Leishmaniaantibodies. Our results suggest that ribosomal vaccine, which prevents pathology in a primary challenge, in combination with parasite persistence might be effective for long-term maintenance of immunity.

Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica , resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria , is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

Inbred Strains Derived from Feral Mice Reveal New Pathogenic Mechanisms of Experimental Leishmaniasis Due to Leishmania major

ABSTRACT Two inbred mouse strains, derived from feral founders, are susceptible to experimental leishmaniasis due to Leishmania major and support a disease of a severity intermediate between those observed in strains C57BL/6 and BALB/c. Mice of the MAI strain develop a severe, nonhealing, but nonfatal disease with no resistance to a secondary parasite challenge. The immunological responses showed a TH2 dominance characterized by an early peak of interleukin-4 (IL-4) and IL-13. However, neutralization of IL-4, which leads to a resistance phenotype in BALB/c mice, has no effect on disease progression in MAI mice. Mice of strain PWK develop a protracted but self-healing disease, characterized by a mixed TH1-plus-TH2 pattern of immune responses in which IL-10 plays an aggravating role, and acquire resistance to a secondary challenge. These features are close to those observed in human cutaneous leishmaniasis due to L. major and make PWK mice a suitable model for the human disease.

Failure of Schistosoma mansoni to reinfect Biomphalariaglabrata snails: acquired humoral resistance or intra-specific larval antagonism?

Failure of snail reinfection by Schistosoma mansoni has been demonstrated in susceptible Biomphalaria glabrata infected with 1 miracidium and subsequently re-exposed to 1 or 5 homologous parasite larvae. The acquisition of ‘resistance’ to secondary parasite infection was time dependent since complete inhibition was observed at 2 weeks and longer following monomiracidial exposure. This phenomenon was still observed in snails challenged 8 weeks after primary infection. Histological observations revealed that sporocysts from the challenge infection were free of encapsulation, their development was stopped and they degenerated slowly in the absence of haemocytic reaction of the host. Under the hypothesis of an acquired homologous resistance mechanism, this strongly suggests that 1 or several unidentified humoral factors are responsible for the non-development of the sporocysts from the challenge infection. However, considering the time-dependent nature of the phenomenon, an intraspecific larval antagonism process between sporocysts resulting from the primary infection and those from the challenge infection may be involved.

Histopathology of Rainbow Trout (Oncorhynchus mykiss) after Long-Term Exposure to Biologically Treated Bleached Kraft Mill Effluent in Experimental Stream Channels

Outdoor experimental streams were used to determine the effects of effluent on histopathology of rainbow trout (Oncorhynchus mykiss). Studies were conducted for 10–11 mo using biologically treated bleached kraft mill effluent at concentrations ranging from 0.5 to 2.0 mg∙L−1 of effluent BOD5 (1.3–5.1% v/v) and for 42 mo at 0.5 BOD5 addition (1.5% v/v). Twenty different tissues from randomly selected fish were examined at the end of each exposure period. Lesions or tissue changes observed in fish from both control and effluent-treated streams were of primary or secondary parasite-induced etiology, a condition typical of natural streams. There was an absence of neoplasia over the range of concentrations. Hematocrit, leucocrit, and liver somatic index remained normal throughout the course of effluent exposure. These data corroborate the lack of effluent effects as determined from measurements of trout growth, survival, production, and reproduction.

NOTE ON CYRTOGASTER VULGARIS WALKER (HYMENOPTERA: PTEROMALIDAE), A SECONDARY PARASITE OF THE ALFALFA BLOTCH LEAFMINER (DIPTERA: AGROMYZIDAE), WITH DESCRIPTIONS OF THE IMMATURE STAGES

Cyrtogaster vulgaris Walker, a pupal parasite of the alfalfa blotch leafminer, Agromyza frontella (Rondani), acts as a secondary agent as well. The adults, which deposit their eggs within host puparia, apparently do not discriminate between healthy leafminers and those parasitized by Dacnusa dryas (Nixon). The egg and larval cephalic structures of C. vulgaris are described and illustrated and the final-instar larval skins of the two parasite species are compared.

PRIMARY AND SECONDARY PARASITES OF AN ALFALFA-INFESTING APHID, THERIOAPHIS SP., IN MANITOBA

In 1984 and 1985 a total of 51 mummies of the genus Therioaphis sp. (Hornoptera: Aphididae) were collected on alfalfa, Medicago sativa L., in several localities in southern Manitoba: Glenlea, Oakbank, Rosenort, St. Adolphe, and Ste. Agathe [status of North American species of Therioaphis is uncertain; some workers regard Therioaphis on alfalfa and those on clover as different species, whereas others regard those found on alfalfa as merely strains of the species from clover (A.G. Robinson, personal comrnunication)]. The mummies were held in gelatin capsules at 20°C and a 16L:8D cycle, and 44 parasite adults that emerged were identified. Two primary parasites pecies. Praon exsolelurn (Nees) and Binodoxys sp. (Hymenoptera: Aphidiidae), were recorded (Table 1). Cocoons from which adults of P. exsoleturn emerged were formed between the mummy and the substratum, whereas cocoons of the two Binodoxys specimens were inside the mummies. The three secondary parasite species (Table 1) emerged only from the hosts with external cocoons and presumably had developed on P. exsoleturn. Each of the seven hosts from which no parasites emerged had an external cocoon which contained a decomposed parasite larva, either P. exsoletum or one of the secondary species.