Cutting edge: Experimentally induced immune activation in natural hosts of simian immunodeficiency virus induces significant increases in viral replication and CD4+ T cell depletion

Chronically SIVagm-infected African green monkeys (AGMs) have a remarkably stable nonpathogenic disease course, with levels of immune activation in chronic SIVagm infection similar to those observed in uninfected monkeys and with stable viral loads for long periods of time. In vivo administration of LPS or an IL-2/diphtheria toxin fusion protein (Ontak) to chronically SIVagm-infected AGMs triggered increases in immune activation and subsequently of viral replication and depletion of intestinal CD4(+) T cells. Our study indicates that circulating microbial products can increase viral replication by inducing immune activation and increasing the number of viral target cells, thus demonstrating that immune activation and T cell proliferation are key factors in AIDS pathogenesis.     

The potential of Beauveria bassiana inoculum formulated into a polymeric matrix for a microbial control of spruce bark beetle

Two local strains of Beauveria bassiana originally isolated from naturally infected spruce bark beetles in Slovakia were tested for their virulence to Ips typographus (IT) and for their compatibility with a polymeric matrix composed of low-molecular polyethylene. Conidia could be homogenously immobilized in the low-molecular polyethylene matrix with no adverse effect on their viability and infectivity. At constant temperature (25°C), viability of immobilized conidial decreased only by 1–2% after 7 or 14 days when compared with non-formulated conidia. In field conditions, viability of conidia formulated in the matrix was even significantly higher than non-formulated conidia 35 days after their application in traps. Conidia incorporated into the polymeric matrix were infective to IT adults in laboratory bioassays. Mean values of LC₅₀ for native conidia (0.72–2.05?×?10⁶ conidia?ml^?1) and conidia immobilized in the polymeric matrix (0.64–1.03?×?10⁵ conidia?mm^?2) demonstrated high virulence. The efficacy of the local strains was significantly higher than that of B. bassiana strains from mycoinsecticides (Boverol^®, Botanigard^® ES and Naturalis-L^®). Results showed potential of this polymeric material for its use in microbial control of IT when mixed with conidia of B. bassiana.     

Mammalian splicing factor SF1 interacts with SURP domains of U2 snRNP-associated proteins

Splicing factor 1 (SF1) recognizes the branch point sequence (BPS) at the 3′ splice site during the formation of early complex E, thereby pre-bulging the BPS adenosine, thought to facilitate subsequent base-pairing of the U2 snRNA with the BPS. The 65-kDa subunit of U2 snRNP auxiliary factor (U2AF65) interacts with SF1 and was shown to recruit the U2 snRNP to the spliceosome. Co-immunoprecipitation experiments of SF1-interacting proteins from HeLa cell extracts shown here are consistent with the presence of SF1 in early splicing complexes. Surprisingly almost all U2 snRNP proteins were found associated with SF1. Yeast two-hybrid screens identified two SURP domain-containing U2 snRNP proteins as partners of SF1. A short, evolutionarily conserved region of SF1 interacts with the SURP domains, stressing their role in protein–protein interactions. A reduction of A complex formation in SF1-depleted extracts could be rescued with recombinant SF1 containing the SURP-interaction domain, but only partial rescue was observed with SF1 lacking this sequence. Thus, SF1 can initially recruit the U2 snRNP to the spliceosome during E complex formation, whereas U2AF65 may stabilize the association of the U2 snRNP with the spliceosome at later times. In addition, these findings may have implications for alternative splicing decisions.     

Gastrointestinal helminth community of loggerhead sea turtle Caretta caretta in the Adriatic Sea

We analysed the intestinal helminth community of 70 loggerhead sea turtles Caretta caretta with a curved carapace length ranging from 25 to 85.4 cm, recovered dead in neritic foraging habitats in the Adriatic Sea in 1995 to 2004. The overall prevalence of infection was high (70.0%), with a mean abundance of 36.8 helminth parasites per turtle. Helminth fauna comprised 5 trematodes (Calycodes anthos, Enodiotrema megachondrus, Orchidasma amphiorchis, Pachypsolus irroratus, Rhytidodes gelatinosus) and 3 nematodes (Sulcascaris sulcata, Anisakis spp., Hysterothylacium sp.), with 6 taxa specific for marine turtles. In terms of infection intensity and parasite abundance, O. amphiorchis was the dominant species (mean intensity: 49.8; mean abundance: 12.8), followed by R. gelatinosus (30.5 and 8.3, respectively) and P. irroratus (23.5 and 7.0, respectively), while larval Anisakis spp. exhibited the highest prevalence (34.3%). The intensity of helminth infection ranged from 1 to 302 (mean: 52.6 ± 69.1) and was not correlated with the size of turtles; this relationship held for all species, except R. gelatinosus (rS = 0.556, p < 0.05). In comparison to other marine habitats, the helminth community of Adriatic loggerheads is characterised by higher species diversity (Shannon-Wiener H' = 1.58) and evenness (E = 0.76), and lower dominance values (Berger-Parker d = 0.35), which can be attributed to the life history and feeding ecology of sea turtles in recruited neritic grounds and the diversity of their benthic prey.     

Characterisation of N-glycans bound to IGFBP-3 in sera from healthy adults

Human IGFBP-3 contains three potential N-linked glycosylation sites. Published data concerning the type and saccharide composition of the N-glycans is scarce. The aim of this study was to characterise N-glycans covalently attached to IGFBP-3 from sera of healthy adults (men and women). In order to do that a panel of eight lectins covering broad saccharide specificity was used: agarose-immobilised SNA (Sambucus nigra agglutinin), Con A (lectin from Canavalia ensiformis), RCA I (Ricinus communis agglutinin I), PHA-E (Phaseolus vulgaris erythroagglutinin), PHA-L (P. vulgaris leukoagglutinin), succinylated WGA (wheat germ agglutinin), ECL (Erythrina cristagalli lectin) and UEA (Ulex europaeus agglutinin). IGFBP-3 interacted with SNA, Con A, RCA I, PHA-E and, to a much lesser extent, with PHA-L. These results indicate that human IGFBP-3 bears mostly biantennary complex type N-glycans with a very high content of α-2,6-linked Sia at their termini. Hybrid type and high-mannose type N-glycans are present, as well as a bisecting GlcNAc residue, which may be core fucosylated. N-glycosylation of IGFBP-3 follows the N-glycosylation pattern of major serum proteins. This study represents a ground for the future research of glycosylation pattern of IGFBP-3 from the circulation of men and women diagnosed with different illnesses.     

Dynamics of Simian immunodeficiency virus-specific cytotoxic T-cell responses in tissues

Although the dynamics of human immunodeficiency virus and Simian immunodeficiency virus (SIV)-specific cytotoxic T cells (CTLs) have been well documented in the blood, little is known regarding CTL development in other tissues. In this study, seven Mamu-A*01+ macaques were inoculated with SIVmac. Two macaques were killed at 21 days of infection, and SIV gag p11C tetramer responses were measured in the blood, axillary and mesenteric lymph nodes, spleen, bone marrow, and thymus. Three with clinical signs of disease were killed and similarly examined. Four macaques were followed throughout disease progression, and intestinal biopsies and blood were examined at regular time points after inoculation. In animals followed prospectively, peak early tetramer responses were detected in the blood (3.9-19% of CD3+ CD8+ T cells) between day 14-21 post-inoculation (p.i.). After day 49, tetramer responses in the blood diminished and remained relatively stable through day 200, ranging from 0.7-6.5% of CD3+ CD8+ T cells. In contrast, tetramer-positive T cells increased in the intestine in later stages of infection (100-200 days p.i.) in all four infected animals (peak values from 5.3 to 28.8%). Percentages of tetramer-positive cells were consistently higher in the intestine than in the blood in all four animals after day 100. In animals with acquired immunodeficiency syndrome, percentages of CTL in tissues were variable, but were consistently higher in the intestine and spleen compared with blood. These data suggest that while high CTL responses develop at a similar rate, and magnitude in both peripheral and mucosal lymphoid tissues in primary SIV infection, mucosal CTL responses may predominate later in the course of the disease.     

Multi-dose Romidepsin Reactivates Replication Competent SIV in Post-antiretroviral Rhesus Macaque Controllers

Viruses that persist despite seemingly effective antiretroviral treatment (ART) and can reinitiate infection if treatment is stopped preclude definitive treatment of HIV-1 infected individuals, requiring lifelong ART. Among strategies proposed for targeting these viral reservoirs, the premise of the “shock and kill” strategy is to induce expression of latent proviruses [for example with histone deacetylase inhibitors (HDACis)] resulting in elimination of the affected cells through viral cytolysis or immune clearance mechanisms. Yet, ex vivo studies reported that HDACis have variable efficacy for reactivating latent proviruses, and hinder immune functions. We developed a nonhuman primate model of post-treatment control of SIV through early and prolonged administration of ART and performed in vivo reactivation experiments in controller RMs, evaluating the ability of the HDACi romidepsin (RMD) to reactivate SIV and the impact of RMD treatment on SIV-specific T cell responses. Ten RMs were IV-infected with a SIVsmmFTq transmitted-founder infectious molecular clone. Four RMs received conventional ART for >9 months, starting from 65 days post-infection. SIVsmmFTq plasma viremia was robustly controlled to <10 SIV RNA copies/mL with ART, without viral blips. At ART cessation, initial rebound viremia to ~10⁶ copies/mL was followed by a decline to < 10 copies/mL, suggesting effective immune control. Three post-treatment controller RMs received three doses of RMD every 35–50 days, followed by in vivo experimental depletion of CD8⁺ cells using monoclonal antibody M-T807R1. RMD was well-tolerated and resulted in a rapid and massive surge in T cell activation, as well as significant virus rebounds (~10⁴ copies/ml) peaking at 5–12 days post-treatment. CD8⁺ cell depletion resulted in a more robust viral rebound (10⁷ copies/ml) that was controlled upon CD8⁺ T cell recovery. Our results show that RMD can reactivate SIV in vivo in the setting of post-ART viral control. Comparison of the patterns of virus rebound after RMD administration and CD8⁺ cell depletion suggested that RMD impact on T cells is only transient and does not irreversibly alter the ability of SIV-specific T cells to control the reactivated virus.     

The diet of the spiny-cheek crayfish Orconectes limosus in the Czech Republic

The composition of the diet of the invasive spiny-cheek crayfish Orconectes limosus was studied using qualitative and quantitative analyses of stomach contents. A total of 368 specimens collected in 2003–2005 and 2008 in Czech localities were examined, predominantly from the Labe (Elbe) and Vltava River basins. Food components were compared for three size classes of crayfish and both sexes. The following conclusions were reached: (1) the spiny-cheek crayfish is an omnivorous species consuming plants, animals and detritus; (2) quantitatively, the main food component of O. limosus is detritus, while the plant component was second; (3) O. limosus may swallow whole food particles up to 4 mm in size, and the bodies of small animals may sometimes be found undamaged in their stomachs.     

Invasive zebra mussel colonisation of invasive crayfish: a case study

We investigated the interaction between two invasive invertebrate species in a shallow Central European flooded sandpit: the epibiosis of Ponto-Caspian zebra mussels Dreissena polymorpha on the American crayfish Orconectes limosus. Between 2004 and 2005, we followed the seasonal variation in number and size of the mussels attached to crayfish bodies, and microhabitats preferred by mussels. The proportion of crayfish colonised by mussels varied seasonally: in spring and early summer it was consistently over 75%, afterwards it dropped temporarily due to loss of bivalves during the crayfish moult, and later increased again due to re-colonisation by often relatively large juvenile mussels. Three different pathways of mussel settlement on crayfish hosts are likely: (1) primary settlement of free-swimming pediveliger larvae; (2) secondary settlement of plantigrade mussels and juveniles; (3) active re-attachment of grown mussels from the substrate to crayfish. This epibiosis was promoted by lack of suitable substrates at the studied locality. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.