Biomedical subjects

D V Lightner

Publications and source records attributed to D V Lightner.

At least 19 recordsLinked to original sources

PubMed2001

Development and application of monoclonal antibodies for the detection of white spot syndrome virus of penaeid shrimp.

Monoclonal antibodies (MAbs) were produced against white spot syndrome virus (WSSV) of penaeid shrimp. The virus isolate used for immunization was obtained from China in 1994 and was passaged in Penaeus vannamei. The 4 hybridomas selected for characterization all produced MAbs that reacted with the 28 kD structural protein by Western blot analysis. The MAbs tested in dot-immunoblot assays were capable of detecting the virus in hemolymph samples collected from moribund shrimp during an experimentally induced WSSV infection. Two of the MAbs were chosen for development of serological detection methods for WSSV. The 2 MAbs detected WSSV infections in fresh tissue impression smears using a fluorescent antibody for final detection. A rapid immunohistochemical method using the MAbs on Davidson's fixed tissue sections identified WSSV-infected cells and tissues in a pattern similar to that seen with digoxigenin-labeled WSSV-specific gene probes. A whole mount assay of pieces of fixed tissue without paraffin embedding and sectioning was also successfully used for detecting the virus. None of the MAbs reacted with hemolymph from specific pathogen-free shrimp or from shrimp infected with infectious hypodermal and hematopoietic necrosis virus, yellow head virus or Taura syndrome virus. In Western blot analysis, the 2 MAbs did not detect any serological differences among WSSV isolates from China, Thailand, India, Texas, South Carolina or Panama. Additionally, the MAbs did not detect a serological difference between WSSV isolated from penaeid shrimp and WSSV isolated from freshwater crayfish.

Animals↗

PubMed2001

Different reactions obtained using the same DNA detection reagents for Thai and Korean hepatopancreatic parvovirus of penaeid shrimp.

Hepatopancreatic parvovirus (HPV) can cause stunted growth and death in penaeid shrimp including Penaeus monodon. We used PCR primers and a commercial DNA probe designed from HPV of Penaeus chinensis (HPVchin) to examine HPV-infected Thai P. monodon (HPVmon). We found that the PCR primers produced a 732 bp DNA amplicon rather than the 350 bp amplicon obtained with HPVchin template and that the DNA probe gave weak to variable in situ DNA hybridization results. In addition, hybridization to PCR products from HPVmon was weak compared with hybridization with PCR products from HPVchin. By contrast, the 732 bp amplicon hybridized strongly with HPVmon-infected cells by in situ hybridization but not with uninfected shrimp tissue or other shrimp viruses, thus confirming its origin from HPVmon. Cloning, sequencing and analysis of the 732 bp amplicon showed that 696 bp (excluding the primer sequences) contained 47% GC content and had only 78% homology to 701 aligned bases from a 3350 bp DNA fragment of HPVchin from GenBank. These results explain why the reagents based on HPVchin gave a different PCR product and weak hybridization results with HPVmon, and they show that multiple primers or degenerate primers may be necessary for general detection of HPV varieties. Together with previously published information on the estimated total genome sizes for HPVchin (approximately 4 kb) and HPVmon (approximately 6 kb), these data support the contention that HPVchin and HPVmon are different varieties or species, in spite of their similar histopathology.

Animals↗

PubMed2001

Detection and quantification of infectious hypodermal and hematopoietic necrosis virus in penaeid shrimp by real-time PCR.

A real-time PCR method using a fluorogenic 5' nuclease assay and a PE Applied Biosystems GeneAmp 5700 sequence detector was developed to detect infectious hypodermal and hematopoietic necrosis virus (IHHNV) in penaeid shrimp. A pair of PCR primers to amplify an 81 bp DNA fragment and a fluorogenic probe (TaqMan probe) were selected from ORF1 (open reading frame 1) of the IHHNV genome. The primers and TaqMan probe used in this assay were shown to be specific for IHHNV and did not react with either hepatopancreatic parvovirus (HPV), white-spot syndrome virus (WSSV), or shrimp DNA. A plasmid, pIHHNV-P4, containing the target IHHNV sequence was constructed and used as a positive control. The concentration of pIHHNV-P4 was determined through spectrophotometric analysis and the plasmid was used for quantitative studies. This real-time PCR assay had a detection limit of 10 copies and a log-linear range up to 5 x 10(7) copies of IHHNV DNA. The assay was then used to quantify IHHNV in infected shrimp collected from 5 locations: Hawaii, Panama, Mexico, Guam, and the Philippines. The quantitative analysis showed that wild-caught, large juvenile Penaeus stylirostris collected from the Gulf of California (Mexico) in 1996 were naturally infected with IHHNV and contained up to 10(9) copies of IHHNV microg(-1) of DNA. Similar quantities of IHHNV were detected in hatchery-raised, small juvenile P. stylirostris collected from Guam in 1995 and in farm-raised, post-larval P. monodon from the Philippines in 1996. Laboratory-infected P. stylirostris contained approximately 10(8) copies of IHHNV 31 d after being fed with IHHNV-infected shrimp tissue. In contrast, individuals of Super Shrimp, a line of P. stylirostris selected for IHHNV resistance, showed no signs of infection 32 d after ingesting IHHNV-infected shrimp tissue. Laboratory-infected P. vannamei also contained approximately 10(8) copies of IHHNV 30 d after being fed infected shrimp tissue. A time-course study of IHHNV replication in juvenile P. vannamei showed that the doubling time in the exponential growth phase was approximately 22 h.

Animals↗

PubMed2001

Detection of hepatopancreatic parvovirus (HPV) of penaeid shrimp by in situ hybridization at the electron microscope level.

A post-embedding in situ hybridization procedure was developed to detect hepatopancreatic parvovirus (HPV) of penaeid shrimp at the ultrastructural level. The procedure was optimized using sections of resin-embedded hepatopancreas from HPV-infected juvenile Penaeus monodon and postlarval P. chinensis. The hepatopancreata were fixed using various fixatives, dehydrated, and embedded in the hydrophilic resin Unicryl. A 592 bp HPV-specific DNA probe, labeled with DIG-11-dUTP, was tested both on semi-thin and ultra-thin sections and examined by light and electron microscopy, respectively. Hybridized probe was detected by means of an anti-DIG antibody conjugated to 10 nm gold particles and subsequent silver enhancement. Hybridization signal intensities were similar with all fixatives tested, but ultrastructure was best preserved with either 2 or 6% glutaraldehyde. Post-fixation with 1% osmium tetroxide improved ultrastructure but markedly decreased hybridization signal and induced non-specific deposition of gold and silver. Under optimized conditions, this technique was used to successfully follow the development of HPV from absorption and transport through the cytoplansm to nuclear penetration, replication and release by cytolysis. The probe signal was consistently observed among necrotic cell debris within the lumen of hepatopancreatic tubules, within the microvillous border of tubule epithelial cells, within the cytoplasm, and within diagnostic HPV intranuclear inclusion bodies. The nucleolus and karyoplasm of patently infected cells (i.e., showing HPV intranuclear inclusion bodies) were almost devoid of signal. Electron-lucent structures, known as intranuclear bodies, commonly found within the virogenic stroma, showed only weak labeling. This is the first use of in situ hybridization to detect HPV nucleic acids with the electron microscope. The technique should be useful for studying the pathogenesis of HPV.

Animals↗

PubMed2001

Traceability of aquatic animals.

Effective methods of traceability are urgently required for use in research as well as in different types of aquaculture operations and to control trade in aquatic animals and products. In regard to the marking of fish, many different tagging methods have been described and the method to be used depends on the purpose and need for tagging. In contrast, for molluscs and crustaceans, only a few methods of marking such animals have been described, due to the practical difficulties. The authors first describe the different methods for tracing fish and fishery products, by means of external tags, such as Floy tags, Carlin tags and passive integrated transponder tags; chemical marking using inorganic substances such as silver nitrate or potassium nitrate, pigments, oxytetracycline, etc.; and several different types of electronic devices in which basic information such as the strain of fish, farm of origin or weight can be stored. Genetic traceability using deoxyribonucleic acid profiling is developing quite rapidly for cultured brood stocks and wild populations. This technique may be used with very high degrees of confidence to assign to or exclude animals or products from their claimed origin, paternity or strain, and may be used as evidence in court proceedings. The second section of this paper describes the traceability of live molluscs for restocking and for human consumption. In these applications, genetic markers have been demonstrated to be suitable. Mechanical tagging on a small scale for research purposes has also been used. Otherwise, the only means of tracing live molluscs are the movement documents and the labelling on boxes that certifies the origin of the commodity. The third section describes the methods available for tracing live and dead crustaceans. A large variety of physical tagging methods for decapod crustaceans is described, such as the injection of biological stains (fast green, Niagara sky blue, trypan red and blue) and external tags such as coloured streamer tags, wire tags and a variety of anchor tags. Furthermore, a number of different internal coding methods, such as the coded micro-wire tags and injected elastomer tags are discussed in detail. As is the case for fish, genetic molecular techniques are also applied in population studies of crustaceans; some of the molecular genetic methods are described. Prawns for human consumption are most frequently packed whole or as tails after the necessary sorting, washing and freezing and the only way of performing a traceback is through documents relating to movement, invoices, health certificates and labelling of the boxes. The minimum requirements for labelling would be the content of the packages, i.e. species, quantity, identification of the manufacturer (name and address), packing place, importer/exporter or vendor of the product, in addition to the loading bill number.

Animal Identification Systems↗

PubMed2000

Identification of genomic variations among geographic isolates of white spot syndrome virus using restriction analysis and Southern blot hybridization.

White spot syndrome virus (WSSV) is widely distributed in most of the Asian countries where penaeid shrimp are cultured, as well as in some regions of the USA. Six geographic isolates of WSSV-1 each from penaeid shrimp from China, India, Thailand, and the US states of Texas and South Carolina, and 1 isolated from crayfish at the National Zoological Park in Washington, DC-were compared by combining the methods of restriction analysis and Southern blot hybridization. DNA was extracted from purified viruses and then digested with selected endonucleases: AccI, BglII, ClaI, BamHI, EcoRI, HindII, HaeI, SacI and XhoI. The blots were detected with digoxigenin-11-dUTP-labeled WSSV genomic probes: LN4, C42 and A6. No distinctive differences among the 5 WSSV isolates from penaeid shrimp were detected; however, differences in the WSSV isolate from crayfish were observed. A 2.8 kb DNA fragment originating from the crayfish isolate and encompassing the LN4 region was subcloned into pBluescript and sequenced for comparison with the LN4 fragment from the Thailand WSSV isolate. The results indicate that some genomic components of WSSV from different geographic regions share a high degree of homology. This method can be used to distinguish between the WSSV isolate from crayfish and the WSSV isolates from penaeid shrimp.

Animals↗

PubMed2000

A non-destructive method based on the polymerase chain reaction for detection of hepatopancreatic parvovirus (HPV) of penaeid shrimp.

Current methods to detect hepatopancreatic parvovirus (HPV) infection of penaeid shrimp depend on invasive techniques that require dissecting the organs infected by this virus. However, sacrificing valuable stocks in order to determine their HPV status can be a drawback in the case of breeding programs. A method was developed for HPV detection by applying a polymerase chain reaction (PCR) assay to fecal samples collected from live HPV-infected shrimp Penaeus chinensis. A pair of PCR primers, 1120F/1120R, which amplify a 592 base pair (bp) region from the virus genome, was designed from previously known HPV sequence information (HPV clone HPV8). PCR amplification with these primers generated a product of the expected size directly from the crude feces of HPV-infected shrimp but not from the feces of specific pathogen-free (SPF) shrimp. The HPV origin of the amplified product was validated by means of an in situ hybridization assay where the product of the amplification, labeled with digoxigenin (DIG)-11-dUTP, showed an intense reaction within hepatopancreatic cells displaying characteristic HPV lesions on HPV-infected shrimp. No reaction to this probe was observed when reacted in situ with sections of the hepatopancreas of SPF specimens or to sections of shrimp infected by the infectious hypodermal and hematopoietic necrosis virus (IHHNV), another parvovirus of penaeid shrimp. These primers were tested for specificity against homologous and nonhomologous viruses and no product was amplified. A fragment of the expected size was obtained only when purified HPV or purified HPV8 plasmid was used as template DNA. Under optimized conditions, these primers detected as little as 1 fg of purified HPV8 plasmid DNA, equivalent to approximately 300 HPV particles. Analysis of fecal samples by PCR may prove useful for non-lethal screening of valuable shrimp of unknown HPV status. This same strategy also might be used for detection of other enteric viruses that infect penaeid shrimp.

Animals↗

PubMed2000

Protein analysis of geographic isolates of shrimp white spot syndrome virus.

Six geographic isolates of the white spot syndrome virus (WSSV) of penaeid shrimp, from China, India, Thailand, South Carolina, Texas, as well as from crayfish kept at the US National Zoo in Washington D. C, were compared by electron microscopy and sodium sulfate polyacrylamine gel electrophoresis (SDS-PAGE). Amino acid compositions of four of the major structural polypeptides of the South Carolina WSSV were analyzed, and three of the four polypeptides were partially sequenced from their NH2 termini. The morphologies of purified virions of the six geographic isolates of WSSV were indistinguishable by transmission electron microscopy. By SDS-PAGE, the protein profiles of the six isolates were very similar, but not identical. They all contained three major polypeptides with sizes of approximately 25, 23 and 19 kDa. A fourth major polypeptide at the 14.5 kDa position was observed in four of the geographic isolates. The WSSV isolated from crayfish presented a slightly different structural protein profile, particularly with regard to the protein in the 19 kDa range that appeared larger in size than those of the other isolates. The NH2 terminal amino acids of the 25, 23 and 14.5 kDa polypeptides of the South Carolina WSSV were sequenced as MDLSFTLSVVTA, MEFGNLTNLDVA, and VARGGKTKGRRG, respectively. No significant homologous sequence was found in the GenBank. These protein sequences have been submitted to the SWISS-PROT Protein Data Bank and assigned the accession numbers P82004, P82005 and P82006.

Amino Acid Sequence↗

PubMed1999

A yellow head virus gene probe: nucleotide sequence and application for in situ hybridization.

A portion of the genome of yellow head virus (YHV) of penaeid shrimp was cloned and the cDNA fragment (1161 bp) was designated clone 3-27. The fragment was labeled with digoxigenin and hybridized in situ to tissue sections of YHV-infected Penaeus vannamei. Positively reacting tissues included those of the lymphoid organ, cuticular epithelium, and gills. In addition, connective tissue of hepatopancreas, heart, antennal gland, hematopoietic organ, nerve tract, midgut cecum and muscle reacted to the probe. The probe was highly specific since it hybridized only to tissues from YHV-infected shrimp. It did not react to those of uninfected shrimp or shrimp infected with WSSV (white spot syndrome virus), IHHNV (infectious hypodermal and hematopoietic necrosis virus), or TSV (Taura syndrome virus). The clone was sequenced, and primers were synthesized for rapid detection of YHV in hemolymph using RT-PCR (reverse transcription-polymerase chain reaction). The strand that constituted the viral sequence in the cDNA was also determined via RT-PCR and in situ hybridization with a single-stranded RNA (ssRNA) probe.

Animals↗

PubMed1998

Reverse transcription polymerase chain reaction (RT-PCR) used for the detection of Taura syndrome virus (TSV) in experimentally infected shrimp.

Taura Syndrome Virus (TSV) has adversely affected the shrimp culture industries of the Americas. First recognized in 1992, this viral agent has spread throughout the shrimp growing regions of South and Central America to become established in North America in the short span of 5 yr. Diagnostic methods for TSV include histopathology, bioassay using susceptible Penaeus vannamei as the indicator species and in situ hybridization with TSV specific complimentary DNA (cDNA) gene probes. An additional method for detecting TSV is through the use of reverse transcription polymerase chain reaction (RT-PCR). Two oligonucleotide primers were selected using the sequence information from a cloned cDNA segment of the TSV genome. The primers, designated 9195 and 9992, used in the RT-PCR procedure amplify a 231 base pair (bp) fragment of the cDNA. Using the RT-PCR technique, TSV has been detected in the hemolymph of P. stylirostris and P. vannamei with experimentally induced TSV infections.

Animals↗

PubMed1998

Taura syndrome of penaeid shrimp: cloning of viral genome fragments and development of specific gene probes.

The ssRNA genome extracted from purified Taura Syndrome Virus (TSV) was transcribed into double-stranded, blunt-ended cDNA and was used to construct cDNA libraries either in pUC 18 or in pBluescript II KS-vectors. Twelve recombinant plasmids chosen after screening of the libraries were subjected to restriction enzyme digestions for determination of size inserts and restriction maps. Two of them, pP15 and pQ1, were selected for probe construction. The inserts, 1500 and 1300 base pairs (bp) respectively, were DIG-11dUTP-labelled and the corresponding probes were named P15 and Q1. On northern blots and dot blots, using different denaturation methods, the 2 probes hybridized specifically with extracted RNA-TSV genome, TSV and infected TS shrimp homogenates. No positive hybridization was obtained with other shrimp viruses tested [Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) and Hepatopancreatic Parvovirus (HPV)]. The specificity of the 2 probes was confirmed by in situ hybridization on histological sections of TS diseased shrimps.

Animals↗

PubMed1998

Differentiation of BP-type baculovirus strains using in situ hybridization.

BP-type viruses infect wild and farmed shrimp species in the Americas and can cause high mortality in larval stages. Histologically, BP disease is characterized by the presence of occlusion bodies (OBs) in the nucleus of hepatopancreatic epithelial cells. By in situ hybridization using different molecular probes, we tested shrimp infected with BP-type viruses collected from several geographical areas. In one shrimp, a case of double infection by 2 different BP-type viruses was noted. This has not been previously reported. The molecular probes recognized only the Pacific strain of BP. This specificity of the probe was confirmed by in situ hybridization tests with some infected shrimp collected from the Atlantic and Pacific coasts. The probes reacted only with infected shrimp obtained from the Pacific coast. These results suggest the existence of at least 2 different BP-type viruses and show that specific probes can be used to differentiate between them.

Americas↗

PubMed1997

Development of a non-radioactive gene probe by PCR for detection of white spot syndrome virus (WSSV).

Combining primers created from the sequence information of two baculo-like viruses of penaeid shrimp, Baculovirus penaei (BP) and Monodon baculovirus (MBV), produced a 750 bp band on a 0.8% agarose gel using White Spot Syndrome Virus (WSSV), from Penaeus monodon, as the DNA template. The PCR fragment was ligated to a plasmid vector, (pGEM-T) and transformed, creating a 3.7 Kbp clone. The DNA insert was sequenced, and the original primer pair was located. Using restriction enzymes, the insert was isolated, excised and non-radioactively labeled. This cloned labeled fragment was tested by in situ hybridization for specificity and reactivity with BP, MBV and WSSV-infected shrimp tissues. The major advantage of this novel method of gene probe development is that no DNA sequence information of the targeted infectious agent needed to be known or available. In addition, tedious viral isolation and purification was circumvented. In this study, knowledge of the possible viral strain was important in limiting the PCR primer pairs investigated. The use of arbitrary primers designed for PCR assays from two other possibly related shrimp viruses, increased the likelihood that a generated PCR product would be specific for WSSV.

Animal Diseases↗

PubMed1997

A new RNA-friendly fixative for the preservation of penaeid shrimp samples for virological detection using cDNA genomic probes.

In situ hybridization analysis of shrimp histological sections, utilizing Taura syndrome virus (TSV) specific cDNA probes, is the most sensitive diagnostic technique presently available for the detection of this penaeid shrimp viral disease. However, false negative genomic probe results are obtained frequently from samples of Pacific white shrimp, Penaeus vannamei, that have been preserved with Davidson's AFA (acetic acid, formaldehyde, alcohol) fixative and that, otherwise, demonstrate pathognomonic TSV lesions by routine histology. This problem was linked to prolonged storage of shrimp samples in Davidson's fixative, which is highly acidic (pH approximately 3.5-4). Degradation of TSV genomic RNA was hypothesized to be due to either fixative- induced acid hydrolysis and/or acidophilic endogenous ribonuclease activity. Routine H and E histology and in situ hybridization analyses were conducted on equal numbers of TSV infected P. vannamei juveniles that were preserved for four different time periods (2, 6, 10 and 14 days) with either Davidson's fixative or a new, near neutral (pH approximately 6.0-7.0), RNA-friendly fixative (R-F) that was developed by the authors. In situ hybridization assays were conducted with and without R Nase precautions and all of the samples tested contained moderate to severe TSV lesions by routine histology. Davidson's preserved samples produced weak TSV probe signals after 2 days fixation, but did not react with the probes in those samples that were stored for > 6 days in the fixative. In contrast, TSV was detectable by gene probe in all of the time treatment samples preserved with the new R-F fixative. Equivalent in situ hybridization results were obtained when the same samples were analyzed in the absence of RNase-free conditions. These findings suggest that TSV RNA is degraded when samples are stored in an acidic fixative, such as Davidson's, for more than 2 days and that this problem can be prevented through preservation of shrimp samples with R-F fixative. The efficacy of this new fixative is demonstrated and the results show that RNase-free conditions are not necessary for conducting TSV in situ hybridization analyses.

Animals↗

PubMed1997

Taura syndrome of marine penaeid shrimp: characterization of the viral agent.

The causative agent of Taura syndrome (TS) was recognized in 1994 to be viral in nature and tentatively classified as belonging to either the family Picornaviridae or Nodaviridae. The work reported here has led to a more definitive classification of this new penaeid virus. Located within the cytoplasm of infected cuticular epithelial cells of penaeid shrimp, the virus is a 31 to 32 nm icosahedral particle with a buoyant density of 1.338+/-0.001 g/ml. Three major (55, 40 and 24 kDa) and one minor (58 kDa) polypeptides constitute its proteinic capsid. Its genome contains a single molecule of ssRNA, which is polyadenylated at the 3' end and approximately 9 kb in length. Based on these characteristics, we believe that TS virus should be included in the family Picornaviridae. Ecuadorian and Hawaiian TS virus isolates were found to be identical in their biophysical, biochemical and biological characteristics, and should be considered as the same virus.

Animals↗

PubMed1997

Risk of spread of penaeid shrimp viruses in the Americas by the international movement of live and frozen shrimp.

Within the past decade, viral diseases have emerged as serious economic impediments to successful shrimp farming in many of the shrimp-farming countries of the world. In the western hemisphere, the viral agents of Taura syndrome (TS) and infectious hypodermal and haematopoietic necrosis have caused serious disease epizootics throughout the shrimp-growing regions of the Americas and Hawaii, while in Asia the viral agents of white spot syndrome (WSS) and yellow head (YH) have caused pandemics with catastrophic losses. The international transfer of live shrimp for aquaculture purposes is an obvious mechanism by which the viruses have spread within and between regions in which they have occurred. Shrimp-eating gulls, other seabirds and aquatic insects may also be factors in the spread of shrimp viruses between and within regions. Another potentially important mechanism for the international spread of these pathogens is the trade in frozen commodity shrimp, which may contain viruses exotic to the importing countries. The viral agents of WSS, YH and TS have been found, and demonstrated to be infectious, in frozen shrimp imported into the United States market. Mechanisms identified for the potential transfer of virus in imported frozen products to domestic populations of cultured or wild penaeid shrimp stocks include: the release of untreated liquid or solid wastes from shrimp importing and processing plants directly into coastal waters, improper disposal of solid waste from shrimp importing and processing plants in landfills so that the waste is accessible to gulls and other seabirds, and the use of imported shrimp as bait by sports fishermen.

Americas↗

PubMed1996

Epizootiology, distribution and the impact on international trade of two penaeid shrimp viruses in the Americas.

Marine penaeid shrimp are effected by approximately twenty viruses, the majority of which were discovered as a result of their negative effects on aquaculture. In the Americas, infectious hypodermal and haematopoietic necrosis (IHHN) virus and Taura syndrome (TS) virus have had a significant negative impact on aquaculture industries and, in one instance, on a commercial fishery. Both viruses have become widely distributed as a consequence of the movement of host stocks for aquaculture. IHHN virus (IHHNV) causes catastrophic losses in cultured and wild Penaeus stylirostris. In marked contrast, P. vannamei is relatively resistant to IHHN but infection results, nonetheless, in poor culture performance. TS virus (TSV) is the 'mirror image' of IHHNV in its effect on P. stylirostris and P. vannamei. TSV causes catastrophic losses in P. vannamei, whereas P. stylirostris is highly resistant to TS. In the less than three years since the discovery of TSV in Ecuador in 1992, the virus has spread rapidly and caused massive production losses in most shrimp-growing countries in the Americas.

Animals↗

PubMed1995

Characterization of hepatopancreatic parvo-like virus, a second unusual parvovirus pathogenic for penaeid shrimps.

The hepatopancreatic parvo-like virus (HPV) of penaeid shrimp was extracted from infected shrimp tissues, purified and subsequently characterized. The viral particles, icosahedral in shape, are 22 nm in diameter and possess a buoyant density of 1.41 g/ml. They contain ssDNA, of approximately 5 kb in size which encodes a single polypeptide of 54 kDa. On the basis of its general characteristics this pathogenic agent belongs to the Parvoviridae family, but because of two unusual characteristics (capsid protein formed with a single polypeptide and genome structure more closely related to the autonomous parvoviruses rather than the densoviruses), it seems to constitute a novel group in the Parvoviridae family.

Animals↗