Lepidopteran transcriptome analysis following infection by phylogenetically unrelated polydnaviruses highlights differential and common responses

The Polydnaviridae is a family of double-stranded DNA viruses that are symbionts of parasitoid wasps. The family is currently divided into two genera, the Ichnovirus (IV) and Bracovirus (BV), which are associated with wasps in the families Ichneumonidae and Braconidae, respectively. IVs and BVs have similar immunosuppressive and developmental effects on parasitized hosts but their encapsidated genomes largely encode different genes. To assess whether IV and BV infection has similar or disparate effects on the transcriptome of shared hosts, we characterized the effects of Hyposoter didymator Ichnovirus (HdIV) and Microplitis demolitor Bracovirus (MdBV) on the fat body and hemocyte transcriptome of Spodoptera frugiperda (Lepidoptera: Noctuidae). Our results indicated that HdIV and MdBV infection alters the abundance of a relatively low proportion of S. frugiperda transcripts at 24 h post-infection. A majority of the transcripts affected by infection also differed between MdBV and HdIV. However, we did identify some host transcripts that were similarly affected by both viruses. A majority of these genes were transcribed in the fat body and most belonged to functional classes with roles in immunity, detoxification, or cell structure. Particularly prominent in this suite of transcripts were genes encoding for predicted motor-related and collagen IV-like proteins. Overall, our data suggest that the broadly similar effects that HdIV and MdBV have on host growth and immunity are not due to these viruses inducing profound changes in host gene expression. Given though that IVs and BVs encode few shared genes, the host transcripts that are similarly affected by HdIV and MdBV could indicate convergence by each virus to target a few processes at the level of transcription that are important for successful parasitism of hosts by H. didymator and M. demolitor.

Analysis of virion structural components reveals vestiges of the ancestral ichnovirus genome

Many thousands of endoparasitic wasp species are known to inject polydnavirus (PDV) particles into their caterpillar host during oviposition, causing immune and developmental dysfunctions that benefit the wasp larva. PDVs associated with braconid and ichneumonid wasps, bracoviruses and ichnoviruses respectively, both deliver multiple circular dsDNA molecules to the caterpillar. These molecules contain virulence genes but lack core genes typically involved in particle production. This is not completely unexpected given that no PDV replication takes place in the caterpillar. Particle production is confined to the wasp ovary where viral DNAs are generated from proviral copies maintained within the wasp genome. We recently showed that the genes involved in bracovirus particle production reside within the wasp genome and are related to nudiviruses. In the present work we characterized genes involved in ichnovirus particle production by analyzing the components of purified Hyposoter didymator Ichnovirus particles by LC-MS/MS and studying their organization in the wasp genome. Their products are conserved among ichnovirus-associated wasps and constitute a specific set of proteins in the virosphere. Strikingly, these genes are clustered in specialized regions of the wasp genome which are amplified along with proviral DNA during virus particle replication, but are not packaged in the particles. Clearly our results show that ichnoviruses and bracoviruses particles originated from different viral entities, thus providing an example of convergent evolution where two groups of wasps have independently domesticated viruses to deliver genes into their hosts.

Characterization of the IkappaB-like gene family in polydnaviruses associated with wasps belonging to different Braconid subfamilies

Polydnaviruses (PDVs) are obligate symbionts of hymenopteran parasitoids of lepidopteran larvae that induce host immunosuppression and physiological redirection. PDVs include bracoviruses (BVs) and ichnoviruses (IVs), which are associated with braconid and ichneumonid wasps, respectively. In this study, the gene family encoding IkappaB-like proteins in the BVs associated with Cotesia congregata (CcBV) and Toxoneuron nigriceps (TnBV) was analysed. PDV-encoded IkappaB-like proteins (ANK) are similar to insect and mammalian IkappaB, an inhibitor of the transcription factor nuclear factor kappaB (NF-kappaB), but display shorter ankyrin domains and lack the regulatory domains for signal-mediated degradation and turnover. Phylogenetic analysis of ANK proteins indicates that those of IVs and BVs are closely related, even though these two taxa are believed to lack a common ancestor. Starting from a few hours after parasitization, the transcripts of BV ank genes were detected, at different levels, in several host tissues. The structure of the predicted proteins suggests that they may stably bind NF-kappaB/Rel transcription factors of the tumour necrosis factor (TNF)/Toll immune pathway. Accordingly, after bacterial challenge of Heliothis virescens host larvae parasitized by T. nigriceps, NF-kappaB immunoreactive material failed to enter the nucleus of host haemocytes and fat body cells. Moreover, transfection experiments in human HeLa cells demonstrated that a TnBV ank1 gene product reduced the efficiency of the TNF-alpha-induced expression of a reporter gene under NF-kappaB transcriptional control. Altogether, these results suggest strongly that TnBV ANK proteins cause retention of NF-kappaB/Rel factors in the cytoplasm and may thus contribute to suppression of the immune response in parasitized host larvae.

A virus essential for insect host-parasite interactions encodes cystatins

Cotesia congregata is a parasitoid wasp that injects its eggs in the host caterpillar Manduca sexta. In this host-parasite interaction, successful parasitism is ensured by a third partner: a bracovirus. The relationship between parasitic wasps and bracoviruses constitutes one of the few known mutualisms between viruses and eukaryotes. The C. congregata bracovirus (CcBV) is injected at the same time as the wasp eggs in the host hemolymph. Expression of viral genes alters the caterpillar's immune defense responses and developmental program, resulting in the creation of a favorable environment for the survival and emergence of adult parasitoid wasps. Here, we describe the characterization of a CcBV multigene family which is highly expressed during parasitism and which encodes three proteins with homology to members of the cystatin superfamily. Cystatins are tightly binding, reversible inhibitors of cysteine proteases. Other cysteine protease inhibitors have been described for lepidopteran viruses; however, this is the first description of the presence of cystatins in a viral genome. The expression and purification of a recombinant form of one of the CcBV cystatins, cystatin 1, revealed that this viral cystatin is functional having potent inhibitory activity towards the cysteine proteases papain, human cathepsins L and B and Sarcophaga cathepsin B in assays in vitro. CcBV cystatins are, therefore, likely to play a role in host caterpillar physiological deregulation by inhibiting host target proteases in the course of the host-parasite interaction.

Bracoviruses contain a large multigene family coding for protein tyrosine phosphatases

The relationship between parasitic wasps and bracoviruses constitutes one of the few known mutualisms between viruses and eukaryotes. The virions produced in the wasp ovaries are injected into host lepidopteran larvae, where virus genes are expressed, allowing successful development of the parasite by inducing host immune suppression and developmental arrest. Bracovirus-bearing wasps have a common phylogenetic origin, and contemporary bracoviruses are hypothesized to have been inherited by chromosomal transmission from a virus that originally integrated into the genome of the common ancestor wasp living 73.7 +/- 10 million years ago. However, so far no conserved genes have been described among different braconid wasp subfamilies. Here we show that a gene family is present in bracoviruses of different braconid wasp subfamilies (Cotesia congregata, Microgastrinae, and Toxoneuron nigriceps, Cardiochilinae) which likely corresponds to an ancient component of the bracovirus genome that might have been present in the ancestral virus. The genes encode proteins belonging to the protein tyrosine phosphatase family, known to play a key role in the control of signal transduction pathways. Bracovirus protein tyrosine phosphatase genes were shown to be expressed in different tissues of parasitized hosts, and two protein tyrosine phosphatases were produced with recombinant baculoviruses and tested for their biochemical activity. One protein tyrosine phosphatase is a functional phosphatase. These results strengthen the hypothesis that protein tyrosine phosphatases are involved in virally induced alterations of host physiology during parasitism.

Genome sequence of a polydnavirus: insights into symbiotic virus evolution

Little is known of the fate of viruses involved in long-term obligatory associations with eukaryotes. For example, many species of parasitoid wasps have symbiotic viruses to manipulate host defenses and to allow development of parasitoid larvae. The complete nucleotide sequence of the DNA enclosed in the virus particles injected by a parasitoid wasp revealed a complex organization, resembling a eukaryote genomic region more than a viral genome. Although endocellular symbiont genomes have undergone a dramatic loss of genes, the evolution of symbiotic viruses appears to be characterized by extensive duplication of virulence genes coding for truncated versions of cellular proteins.

Polydnavirus genome: integrated vs. free virus

Polydnaviruses are unique because of their obligatory association with thousands of parasitoid wasp species from the braconid and ichneumonid families of hymenopterans. PDVs are injected into the parasitized hosts and are essential for parasitism success. However, polydnaviruses are also unique because of their genome composed of multiple dsDNA segments. Cytological evidence has recently confirmed the results of genetic and molecular analyses indicating that PDV segments were integrated in the wasp genome. Moreover a phylogenetic study performed using the age of available fossils to calibrate the molecular clock indicated that the polydnaviruses harboured by braconid wasps have resided within the wasp genome for approximately 70 million years. In the absence of horizontal transmission, the evolution of the PDV genomes has been driven exclusively by the reproductive success they have offered the wasps. The consequences of this particular selection pressure can be observed in the gene content of certain PDV genomes from which increasing sequence data are available. Molecular mechanisms already identified could be involved in the acquisition and loss of genes by the PDV genomes and lead us to speculate on the definition of the virus genome.

Concurrent validity of the Bayley Scales of Infant Development II Motor Scale and the Peabody Developmental Motor Scales in two-year-old children

Concurrent validity of the Bayley Scales of Infant Development, Second Edition (BSID II) Motor Scale and the Peabody Developmental Motor Scales (PDMS) was examined by administering both tests to 38 two-year-old Native American children. A correlation analysis of age equivalent scores indicated very good to high correlation for the BSID II Motor Scale with the PDMS Fine Motor Scale (PDFMS) (r = .87) and the PDMS Gross Motor Scale (PDGMS) (r = .83). A correlation analysis of standard scores showed poor to unacceptable correlation between the BSID II Motor Scale with the PDFMS (r = .64) and the PDGMS (r = .49); further, there was poor agreement between the classifications of significantly delayed, mildly delayed, and within normal limits performance on each test. The PDFMS tended to classify children lower than the BSID II Motor Scale. The scores of the relatively younger children within each of the PDMS 6-month age categories agreed less between the tests than did the scores of the relatively older children. In conclusion, this study provides evidence for the concurrent validity of the BSID II Motor Scale and the PDMS for age equivalent scores, but not for standard scores of 2-year-old children. Professionals must be aware of the strengths and limitations of the BSID II and the PDMS, and choose appropriately to avoid denial of or over-referral for services for young children.

Motor development of Native American children on the Peabody Developmental Motor Scales

OBJECTIVE

Native American children have not been widely represented in the normative samples of standardized tests assessing motor development. This study investigated the cultural relevance of the Peabody Developmental Motor Scales (PDMS) in 2-year-old Native American children who are typically developing.

METHOD

The PDMS was administered to a sample of 44 Pueblo children who were 24 months through 35 months of age and typically developing. Each child's family also completed a parent questionnaire addressing the child's development and family demographics. Participant scores were compared with those of the normative sample.

RESULTS

The sample scored significantly lower than the normative sample (p < or = .001) on the Fine Motor Scale, and, when gender was taken into consideration, all but the older girls (30 months-35 months of age) had significantly lower scores. All but the younger girls (24 months-29 months of age) scored within the normal range on the Gross Motor Scale.

CONCLUSION

Our results with this small sample suggest that caution be used when comparing motor performance (especially fine motor abilities) of 2-year-old Native American children against the PDMS normative data.

Proposed new bladder volume monitoring device based on impedance measurement

A new implantable bladder volume-monitoring device based on the impedance measurement of the detrusor muscle is described. The system is completely autonomous and forms a mixed-signal (analogue/digital) feedback loop with a neuro-stimulator to rectify bladder dysfunctions (incontinence and retention) through neuromuscular stimulation techniques. A programmable instrumentation amplifier and a signal processing block, to eliminate the artefacts caused by the patient's movements, have been designed and tested. The layout for the signal processing block has been realised in 0.8 micron BiCMOS technology.

Implantable volume monitor and miniaturized stimulator dedicated to bladder control

This paper describes a new miniaturized implantable bladder controller that is composed of 4 main parts: a volume monitoring device based on the tomography approach, a fully programmable miniaturized central processor and stimulator, a bidirectional data and power link, and an external controller. The proposed system is intended to restore both normal bladder functions (retention and voiding) to spinal cord injured patients. The system contains a mixed-signal (analog/digital) feedback loop to command the bladder functions through neuromuscular stimulation techniques. The implantable circuitry is powered by a single encoded radiofrequency carried and may have up to 8 independently controlled monopolar (4 bipolar) channels. The microstimulator is able to generate a wide range of stimulation patterns, including selective stimulation waveforms. In addition, an optical link transmits the state of the implant and volume monitoring results to the external controller.

Stability of Bayley Motor Scale scores in the first year of life

The purpose of this study was to determine whether Bayley Motor Scale scores were stable in infants during the first year of life, that is, whether each individual infant's score was essentially the same at each of the five test ages. Subjects were 15 low-risk and 8 high-risk infants with Bayley Scales of Infant Development Motor Scale scores at 2, 3, 4, 8, and 12 months. All high-risk and most low-risk infants also had outcome scores at either 24 or 36 months. For the group as a whole, and for all infants with "normal" outcomes, subjects did not change ranks over the six test ages (ie, high-scoring infants' ranks remained high and low-scoring infants' ranks remained low), but scores varied significantly from test to test. Scores of infants with "non-normal" outcomes did not vary significantly from test to test. The highest and lowest scores of 75% of the infants with normal outcomes and 57% of the infants with non-normal outcomes differed significantly. Four patterns of variations of Bayley Motor Scale scores over the five test ages of the first year after birth were identified. The first pattern included three infants with the most stable scores. The three remaining patterns were different from each other, but a consistent feature of each was a peak at 4 months. Finally, scores at 3 and 8 months were best able to correctly identify outcome. A single Bayley Motor Scale score may not reflect an infant's true abilities; some factor may be inflating scores at age 4 months.