6th Conference Program (Greek)
Created & Hosted
by HR-Net
Hellenic Virology
Volume 4, Number 1, 1999
Abstracts
- Biology of enteroviruses: structure, function, pathogenesis and evolution. Part I.
N. Siafakas, A. Georgopoulou, P. Markoulatos, N. Spyrou - Viruses transmitted to domestic animals by arthropods or rodents
M. Papanastassopoulou, G. Koptopoulos, V. Spyrou - A preliminary serological investigation of equine herpes and influenza viruses
V. Spyrou, G. Koptopoulos, M. Papanastassopoulou, M, Artopiou - The importance of IgG, IgA and IgM antibodies in laboratory diagnosis of human infection from Coxsackie B viruses
B.E. Vagiakou-Voudris, P. Karaboyia-Karafyllides, A. Varouta, D. Bouzeits, G. Mitsakou, D. Mylona-Petropoulou - Safety of genetically engineered vaccines against suid herpesvirus 1: Comparison of gE- and TK- single deleted mutants in the pig
S.K. Kritas (1), H.J. Nauwynck (2), M.B. Pensaert (2), S.C. Kyriakis (3)
Virology Department, Hellenic Pasteur Institute, 11521 Athens, Greece
Hellenic Virology, 1999, 4(1): 7-24.
The purpose of the present study is the presentation of the most recent advances in the biology of enteroviruses, including the clinical and epidemiological significance of these data. The genusof enteroviruses is comprised of 64 antigenically distinct serotypes and is the most important of the picornavirus family in terms of human pathogenicity. The members of this genus are characterized by their non-enveloped icosahedral capsid of two-, three- and five-fold symmetry, 30nm in diameter, which is made up of 60 copies of pentameric intermediates of 4 proteins: VP1, VP2, VP3 and VP4. These capsid proteins protect an approximately 7500bp-ling, RNA positive-sense genome, which consists of a highly conserved 5'-UnTranslated Region (5'-UTR), and Open Reading Frame (ORF) that includes the genetic information for both structural and functional proteins of the virus, a 3'-UTR and a poly(A)-tract. The genome is also covalently attached to a small, virus-encoded protein, VPg which is probably important for RNA replication. Due to the highly conserved nature of the 5'-UTR and its distinct secondary structure as predicted by its high G+C content, this region is considered to be important for the success of viral infection. The 3'-UTR at the other side of the genome has a variable length amongst the different enterovirus members but the phylogenetic conservation ofits predicted secondary structure suggests a likely functional significance. The ORF is first transcribed into a large polyprotein which is autocatalytically cleaved by tw major viral proteases, 2A which performs the initial cleavage between structural and non-structural proteins and 3C which performs most of the rest of the protein processing. 2A is also considered to be responsible for the cleavage of the cellular protein p220, which is a part of the cap complex and consequently, the virus exhibits cap-independent protein synthesis, something which shuts down the respective machinery of the host. The capsid proteins VP1, VP2 and VP3 are similar structurally, since they share a common, eight-stranded beta-barrel form and they differ primarily at the size of the loops that protrude from the beta-sheets that comprise the core of the beta-barrel and at other structural details. The small VP4 protein is nothing more than an extension of the amino-terminus of VP2 and, whereas the other three dominate the surface of the capsid, VP4 is hidden from the surface, located at the interior of the capsid. A canyon running at a steady radius around the five-fold symmetry axis is flanked by VP1 and VP3 and its importance for antibody avoidance and virus attachment to the host membrane is discussed. Several cellular receptors for enteroviruses have been identified so far and these include PVR forpolioviruses, ICAM-1 for Coxsackie A13, A18, A21 and HRV viruses, DAF also for Coxsackie A21, the integrins for Coxsackie avb3 for Coxsackie A9, CAR for Coxsackie B viruses, etc.
Laboratory of Microbiology & Infectious Diseases, Faculty of Veterinary Medicine, Aristotelian University of Thessaloniki, 54006 Thessaloniki, Greece
Hellenic Virology, 1999, 4(1): 25-39.
Different mammals and birds can be infected by arboviruses belonging to the Togaviridae, Flaviviridae, Rhabdoviridae, Orthomyxoviridae, Bunyaviridae, Reoviridae and Asfarviridae families. Additionally, some domestic animals can also be infected by the encephalomyocarditis virus, which is transmitted by rodents and belongs to the Picornaviridae family. Arboviruses are usually maintained in nature by a continuous cycling between an arthropod host (biological vector) and an animal, which is the principal vertebrate host. The latter are usually wild mammals and birds, sometimes reptiles and amphibians and rarely domestic animals. The vertebrate and arthropod hosts are reservoirs for many arboviruses in nature. Rodents and perhaps pigs, are the encephalomyocarditis reservoirs. Most arboviruses produce subclinical infection in domestic animals, but about 30 of them are pathogenic and cause severe, often fatal disease. Many arboviruses of domestic animals cause inapparent or apparent disease in humans. In Greece, two epidemics of bluetongue virus disease were reported in some Aegean islands in 1979 and 1998. The presence of antibodies to some other arboviruses had been demonstrated in domestic mammals and birds. Other arbovirus diseases have not occured. Sporadic outbreaks of encephalomyocarditis have been reported between 1989 and 1996 in Northern Greece. Control of arbovirus infections relies on the elimination of transmissible agents and on vaccinations. Similar measures could be taken for controlling encephalomyocarditis.
Laboratory of Microbiology & Infectious Diseases, Faculty of Veterinary Medicine, Aristotelian University of Thessaloniki, 54006 Thessaloniki, Greece
Hellenic Virology, 1999, 4(1): 40-45.
The purpose of the present preliminary survey was to investigate the distribution of equine herpesviruse 1 and 4 and of equine influenza virus in certain areas of Greece. Serum samples were collected from 391 horses with a good management (Athens race course, a horse breeding station and horse clubs) and from 884 "rural" horses. The horses with the good management were vaccinated twice a year, whereas the rural ones were not. Antibodies against herpesviruses were detected by the complement fixation test and against influenza virus by the haemmagglutination inhibition assay. Of the collected sera, 290 were tested for herpesvirus 1 antibodies by ELISA and by the use of a synthetic peptide as antigen. This peptide was produced for the virus glycoprotein gC, by the use of phage epitope libraries technique. The results showed that virtually no antibodies could be detected against EHV-1 and 4 in the animals with the good management, whereas they were detected in the "rural" horses (11.6% for EHV-1 and 13.5% for EHV-4). Influenza virus antibodies were detected in horses with good management, 81% for Prague and 79.3% for Miami strains. The "rural" horses had lower positivity, 10.4% for Miamia and 14% for Prague strains. It seems that vaccinal antibodies of both herpesviruses in horses with the good management cease quickly, whereas those of the influenza virus remain for longer period. The ELISA results showed the need for further improvement of the assay.
Microbiology Department & National Reference Center for Rubella, Athens District Hospital "G. Gennimatas"
Hellenic Virology, 1999, 4(1): 46-50.
Serum samples of 580 patients with clinical picture similar to infection of viruses Coxsackie B and 300 serum samples of healthy population were evaluated for IgG, IgA and IgM antibodies. Immunofluorescent assay was used for the determination of the results. From the 580 serums samples of suspected patients, 120 (31.24%) were found to be positive for IgG antibodies in titer >1/640, 52 were found positive for IgA antibodies in titer >1/20 and 60 for IgM antibodies in titer >1/40. In 300 serum samples of healthy population, 130 were positive for IgG antibodies (43.33%). It seems that the detection of all types of antibodies (IgG, IgA, IgM) is especially useful for the early diagnosis of infection with Coxsackie B viruses.
(1) Clinic of Medicine, Faculty of Veterinary Medicine, University of Thessaly, 43100 Karditsa, Greece (2) Laboratory of Virology, Faculty of Veterinary Medicine, University of Gent, 9820 Merelbeke, Belgium and (3) Clinic of Productive Animal Medicine, Faculty of Veterinary Medicine, University of Thessaloniki, 54006 Macedonia, Greece
Hellenic Virology, 1999, 4(1): 51-56.
The purpose of this study was to evaluate the role that viral proteins TK and gE play in neuropathogenicity and neuroinvasion of suid herpesvirus 1 (SHV-1 or pseudorabies of Aujeszky's disease virus), and to compare the results of their deletion in pigs. One-week-old conventional pigs and without antibodies against SHV-1 were intranasally inoculated with 10exp7 TCID50 of the Ka strain of SHV-1 or its single-deleted TK and gE mutants. The neural invasion and replication of the strains were examined in the trigeminal nervous pathway (nasal mucosa, trigeminal ganglion = 1st level. pons/medulla = 2nd level and cerebellum/thalamus = 3rd level) and the olfactory nervous pathway (olfactory mucosa = 1st level, olfactory bulb = 2nd level and lateral olfactory gyrus, rostral perforated substance and piriform lobe = 3rd levels) by virus titration in cell culture. The pigs inoculated with the Ka parental strain have developed neurological disease and died within 5 days post-inoculation, whilst none of the Ka TK- or Ka gE- inoculated pigs have developed nervous disorders during a similar period. The Ka strain invaded and replicated at high titers in all neuronal levels of both pathways. The Ka gE-deleted strain invaded only up to the 2nd level of the trigeminal pathway and only up to one of the 3rd levels of the olfactory pathway (lateral olfactory gyrus) with titers being significantly lower in neural tissues compared to the parental strain (P<0.05). The Ka TK-deleted strain invaded only up to the 1st level of the trigeminal pathway and only up to one of the 3rd levels of the olfactory pathway (lateral olfactory gyrus) with titers being dramatically reduced in neural tissues compared to the parental strain (P<0.05). In addition, when the two mutants were compared with each other, no substantial differences were detected with respect to their neuroinvasive characteristics. Conclusively, the results of this study confirm the important role that TK and gE proteins play in the neuropathogenicity of SHV-1 in pigs, and are highly suggestive of the necessity of the deletion of these proteins in order that a high degree of vaccine attenuation will be achieved.