Host interaction

In this chapter, we will explore the importance of proteomics in studying virus-host interactions in several viral systems including HCMV, KSHV, EBV, HSV, HIV-1, HTLV-1, and HCV. We will also describe the methods that have been employed to study viral disease progression using several techniques including 2DE, LC-MS/MS, SELDI, and protein microarrays. 

T-lymphotropic virus (HTLV), and the HIV have been analyzed and will be reviewed here. 

Viral particles of HCMV and Kaposi s sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) have recently been examined. During the her-pesviral replicative cycle, different viral particles are formed. For HCMV, this includes mature, infectious virions, noninfectious enveloped particles, and dense bodies [6]. Similarly for KSHV, only a portion of the produced virus particles is infectious [40]. Therefore, analysis of infectious virions requires their separation from the noninfectious and immature forms. Density ultacentrifugation gradients are typically used to separate the various forms. Each fraction can be analyzed by electron microscopy to determine the level of purity [6,41] or by assaying for viral DNA and an envelope glycoprotein [40]. 

Following gradient purification of virions, LC/MS/MS was used to identify the components of the HCMV virion [6]. The results were verified by coupling high-accuracy mass measurements with LC and FT-ICR (Fourier transform ion cyclotron resonance) MS. Fifty-nine proteins were identified including 12 proteins encoded by known HCMV ORFs not previously known to reside in virions. The classes of proteins identified included capsid proteins, tegument proteins, glycoproteins, and 12 proteins involved in DNA replication and transcription. Additionally, 12 more viral polypeptides were identified that had not been previously characterized [6]. 

Using the intensifies in the FT-ICR spectra, the relative quantities of the virion proteins were determined, indicating that 50% of the virion was composed of 

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T-Lymphocytes (4,5) and other cellular components of the immune system also have equally wide implications in regulation of the normal immune system. The T-lymphocytes play a central role in the body s response to harmful antigens and tumor—host interaction (4). Responses involve antigens derived from vimses, bacteria, parasites, and tumors. T-ceUs also participate in the immune surveillance response, where self-antigens are recognized, but usually sequestered within the cell and, when exposed, become markers of cellular damage. 

A much better understanding of the pathogenesis of the vims and vims-host interactions are requited for the efficient development of the vaccine. Recently, DNA immunization is being proposed as a means to stimulate the appropriate Th 1 response which might provide long-term protection (81). 

TIGHE M R, CICLITIRA p J (1995) The gluteu-host interaction. Baillieres Clin Gastroenterol. 9 211-30. 

Fig. 6. Diagrammatic (two-dimensional) representation of different modes of lattice inclusions involving coordinative (H-bond) interactions (indicated by broken lines) (a) cross-linked matrix type of inclusion (host-host interaction, true clathrate) (b) coordinatoclathrate type of inclusion (coordinative host-guest interaction, coordination-assisted clathrate)...

Fig. 18. Closed H-bond loops (dotted and hatched regions indicating host-guest and host-host interactions, respectively) in alcohol inclusions of l and 26. Packing excerpts show the rings formed in the coordinatoclathrates (a) 1 1-PiOH (2 1)77>, (b) 26 1-BuOH (1 1) 71 (H-atoms of the hosts are shown as sticks only)...

Forward Genetic Analysis of Plant-parasitic Nematode-Host Interactions... 

Nematode-host interactions are complex and poorly understood. The relationship between cyst nematodes and their hosts appears to have co-evolved, and as a result there are numerous genes for host resistance that are complemented by nematode parasitism genes (Triantaphyllou, 1987). Different alleles of these genes may interact in various combinations to give... 

For much of its life cycle a parasite s environment is its host. A principal, and potentially lethal, feature of this environment is the host immune response. Diversity in parasites interactions with this aspect of their environment may therefore be expected. The host immune response varies between different hosts and so, if this is considered as a selection pressure, it may produce the ideal conditions for the generation of diversity in immune-mediated parasite-host interactions. 

Another interesting observation is that several species of filarial nematodes have been shown to express chitinase (Fuhrman, 1995). Indeed the chitinase of A. viteae infective stage larvae (L3) is the main target of the protective humoral immune response when jirds are vaccinated with irradiated attenuated L3s (Adam et al., 1996 see also Chapter 10). It remains to be established whether there is an interaction between the parasite s oligo-chitin A-glycans and chitinase and whether such an interaction has a role to play in parasite-host interaction. 

Phalipon A, Sansonetti PJ Microbial-host interactions at mucosal sites. Host response to pathogenic bacteria at mucosal sites. Curr Top Microbiol Immunol 1999 236 163-189. 

Because the size regime of n=l-6 atoms is of great practical significance to the spectroscopic, chemical and catalytic properties of supported metal clusters in both weakly and strongly interacting environments (28), it is important to study very small metal clusters in various types of substrate as well as in the gas phase. In this way, one can hope to develop a scale of metal cluster-support effects (guest-host interactions) and evaluate the role that they play in diverse technological phenomena. 

One of the objectives of this paper is to evaluate the spectroscopic and photochemical consequences of the occurrence of markedly disparate guest-host interactions in the ground and optically excited states of Cu and Ag atoms, and some of their low nuclearity clusters, in rare gas as well as other supports. Original papers should be consulted for details. 

The observation of large Stokes shifts for the 2P-2S transition of entrapped Ag atoms indicates that the guest-host interactions are markedly different for the 2S and 2P states of this system and can be explained in terms of matrix cage relaxation effects. 

Studies of the energetics and dynamics of Cu2 and Ag2 in rare gas solids have also been completed (31,34). The absorption and fluorescence spectra are similarly indicative of strong guest-host interactions in the low lying states of Cu2 and Ag2 Rather than presenting the spectroscopic and photolytic details, a summary of the observed radiative relaxation processes of visible and uv excited Cu2 and Ag2 in rare gas solids is shown below ... 

The absorption and fluorescence spectra of Ag2 in rare gas solids are also clearly indicative of strong guest-host interactions involving the A1 and C1 Instates of Ag2 as summarized below ... 

From the above discussion, it should be possible to appreciate how extremely subtle differences in guest-host interactions in the ground and excited states of Cu and Ag atoms and dimers in both non-reactive and reactive supports can lead to dramatically distinct chemical reactivity patterns and dynamical processes. Photochemical and photophysical phenomena of this kind should provide chemists of the 21st century with a rich field for fundamental and applied research, offering considerable scope for experimental challenges and intellectual stimulation. 

The parasite-host interaction continuously exerts selective pressure(s) on both insects to survive. The host insect presents a particularly challenging environment for endoparasites because of the rapid development and differentiation that characterize parasite and host life cycles (21,22, 80, 81). Endoparasites may exploit a variety of agents to suppress or avoid host defenses and to modify the normal development of the host to match their need polydnaviruses, venoms, oviduct secretions, and protective materials coating the parasite egg or produced by the endo-parasite as it develops within its host. 

GH Heilmeier and LA Zanoni, Guest-host interactions in nematic liquid crystals a new electrooptic effect, Appl. Phys. Lett., 13 91-92, 1968. 

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