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The immune response of hemocytes of the insect Oncopeltus fasciatus against the flagellate Phytomonas serpens.

Alves e Silva TL, Vasconcellos LR, Lopes AH, Souto-Padrón T - PLoS ONE (2013)

Bottom Line: The parasites reached the O. fasciatus salivary glands at least six hours post-infection.After 72 hours post-infection, many parasites were attached to the salivary gland outer surface.Thus, the cellular responses did not kill all the parasites.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Centro de Ciências da Saúde, Bloco I, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, Brazil.

ABSTRACT
The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites.

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Hemocytes phagocytize P.serpens.(A) The ratio of hemocytes containing phagocytized parasites increased throughout the time course of the infection. Each point represents the mean ± standard error of eight samples; each sample was obtained by pooling together the hemolymph of three insects. The mean values were compared using One-way ANOVA with Dunnett's post test (p<0.05). The mean values of 24, 48 and 72 hpi differed significantly from the mean value of 6 hpi, as indicated by asterisks. (B) The number of parasites within the hemocytes increased during the infection. The hemocytes were fixed followed by Giemsa staining at 6, 24, 48 and 72 hpi.
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pone-0072076-g006: Hemocytes phagocytize P.serpens.(A) The ratio of hemocytes containing phagocytized parasites increased throughout the time course of the infection. Each point represents the mean ± standard error of eight samples; each sample was obtained by pooling together the hemolymph of three insects. The mean values were compared using One-way ANOVA with Dunnett's post test (p<0.05). The mean values of 24, 48 and 72 hpi differed significantly from the mean value of 6 hpi, as indicated by asterisks. (B) The number of parasites within the hemocytes increased during the infection. The hemocytes were fixed followed by Giemsa staining at 6, 24, 48 and 72 hpi.

Mentions: At 6 hpi, 24% of total hemocytes contained phagocytized parasites. This number increased to 57.4% after 24 hpi, 85% after 48 hpi and 87% after 72 hpi (Fig. 6A). In Giemsa-stained preparations, parasites were observed within hemocytes at 6 hpi (Fig. 6B). The number of parasites within hemocytes increased with the increase in infection time. After 72 h, some hemocytes contained plenty of parasites and appeared damaged due the increased number of intracellular parasites (Fig. 6B). Therefore, the hemocytes actively take part in the host immune response during P. serpens infection and the parasite may multiply inside hemocytes.


The immune response of hemocytes of the insect Oncopeltus fasciatus against the flagellate Phytomonas serpens.

Alves e Silva TL, Vasconcellos LR, Lopes AH, Souto-Padrón T - PLoS ONE (2013)

Hemocytes phagocytize P.serpens.(A) The ratio of hemocytes containing phagocytized parasites increased throughout the time course of the infection. Each point represents the mean ± standard error of eight samples; each sample was obtained by pooling together the hemolymph of three insects. The mean values were compared using One-way ANOVA with Dunnett's post test (p<0.05). The mean values of 24, 48 and 72 hpi differed significantly from the mean value of 6 hpi, as indicated by asterisks. (B) The number of parasites within the hemocytes increased during the infection. The hemocytes were fixed followed by Giemsa staining at 6, 24, 48 and 72 hpi.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756046&req=5

pone-0072076-g006: Hemocytes phagocytize P.serpens.(A) The ratio of hemocytes containing phagocytized parasites increased throughout the time course of the infection. Each point represents the mean ± standard error of eight samples; each sample was obtained by pooling together the hemolymph of three insects. The mean values were compared using One-way ANOVA with Dunnett's post test (p<0.05). The mean values of 24, 48 and 72 hpi differed significantly from the mean value of 6 hpi, as indicated by asterisks. (B) The number of parasites within the hemocytes increased during the infection. The hemocytes were fixed followed by Giemsa staining at 6, 24, 48 and 72 hpi.
Mentions: At 6 hpi, 24% of total hemocytes contained phagocytized parasites. This number increased to 57.4% after 24 hpi, 85% after 48 hpi and 87% after 72 hpi (Fig. 6A). In Giemsa-stained preparations, parasites were observed within hemocytes at 6 hpi (Fig. 6B). The number of parasites within hemocytes increased with the increase in infection time. After 72 h, some hemocytes contained plenty of parasites and appeared damaged due the increased number of intracellular parasites (Fig. 6B). Therefore, the hemocytes actively take part in the host immune response during P. serpens infection and the parasite may multiply inside hemocytes.

Bottom Line: The parasites reached the O. fasciatus salivary glands at least six hours post-infection.After 72 hours post-infection, many parasites were attached to the salivary gland outer surface.Thus, the cellular responses did not kill all the parasites.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Centro de Ciências da Saúde, Bloco I, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, Brazil.

ABSTRACT
The genus Phytomonas includes parasites that are etiological agents of important plant diseases, especially in Central and South America. These parasites are transmitted to plants via the bite of an infected phytophagous hemipteran. Despite the economic impact of these parasites, many basic questions regarding the genus Phytomonas remain unanswered, such as the mechanism by which the parasites cope with the immune response of the insect vector. In this report, using a model of systemic infection, we describe the function of Oncopeltus fasciatus hemocytes in the immune response towards the tomato parasite Phytomonas serpens. Hemocytes respond to infection by trapping parasites in nodular structures and phagocytizing the parasites. In electron microscopy of hemocytes, parasites were located inside vacuoles, which appear fused with lysosomes. The parasites reached the O. fasciatus salivary glands at least six hours post-infection. After 72 hours post-infection, many parasites were attached to the salivary gland outer surface. Thus, the cellular responses did not kill all the parasites.

Show MeSH
Related in: MedlinePlus