Assessment of transmission risk in WSSV-infected shrimp Litopenaeus vannamei upon cooking

White spot syndrome virus has been a threat to the global shrimp industry since it was discovered in Taiwan in 1992. Thus, shrimp-producing countries have launched regulations to prevent import of WSSV-infected commodity shrimp from endemic areas. Recently, cooked shrimp that is infected with WSSV tested positive by PCR. However, there is no study to determine the infectivity of WSSV in cooked shrimp that tested positive by PCR. In the present study, WSSV-infected shrimp were cooked at boiling temperature for different times including 0, 1, 3, 5, 10 and 30 min. Upon exposure to boiling temperature, WSSV-infected shrimp were fed to SPF shrimp (Litopenaeus vannamei). The result showed experimentally challenged shrimp from 0-min treatment (positive control) indeed got infected with WSSV. However, experimentally challenged shrimp that were fed tissues boiled at 1, 3, 5, 10 and 30 min were not infected with WSSV. Mortality data showed that only the positive control (0-min) treatment displayed high mortality, whereas no mortality was observed in any other treatment category. These findings suggest that cooking shrimp at boiling temperature for at least 1 min might prevent any potential spread of WSSV from endemic countries to other geographical areas where WSSV has not yet been reported.

The Molecular Epidemiology and Phylogeny of Torque Teno Virus (TTV) in Jordan

Torque teno virus (TTV) is the most common component of the human blood virobiota. Little is known, however, about the prevalence of TTV in humans and the most common farm domesticates in Jordan, or the history and modality of TTV transmission across species lines. We therefore tested sera from 396 Jordanians and 171 farm animals for the presence of TTV DNA using nested 5'-UTR-PCR. We then performed phylogenetic, ordination and evolutionary diversity analyses on detected DNA sequences. We detected a very high prevalence of TTV in Jordanians (~96%); much higher than in farm animal domesticates (~29% pooled over species). TTV prevalence in the human participants is not associated with geography, demography or physical attributes. Phylogenetic, ordination and evolutionary diversity analyses indicated that TTV is transmitted readily between humans across the geography of the country and between various species of animal domesticates. However, the majority of animal TTV isolates seem to derive from a single human-to-animal transmission event in the past, and current human-animal transmission in either direction is relatively rare. In conclusion, animal TTV in Jordan is historically derived from human variants; however, ongoing human-animal TTV exchange is minimal and zoonotic infection seems to be of limited importance.

Modelling Ranavirus Transmission in Populations of Common Frogs (Rana temporaria) in the United Kingdom

Ranaviruses began emerging in common frogs (Rana temporaria) in the United Kingdom in the late 1980s and early 1990s, causing severe disease and declines in the populations of these animals. Herein, we explored the transmission dynamics of the ranavirus(es) present in common frog populations, in the context of a simple susceptible-infected (SI) model, using parameters derived from the literature. We explored the effects of disease-induced population decline on the dynamics of the ranavirus. We then extended the model to consider the infection dynamics in populations exposed to both ulcerative and hemorrhagic forms of the ranaviral disease. The preliminary investigation indicated the important interactions between the forms. When the ulcerative form was present in a population and the hemorrhagic form was later introduced, the hemorrhagic form of the disease needed to be highly contagious, to persist. We highlighted the areas where further research and experimental evidence is needed and hope that these models would act as a guide for further research into the amphibian disease dynamics.

Assessing the Epidemic Potential of RNA and DNA Viruses

Many new and emerging RNA and DNA viruses are zoonotic or have zoonotic origins in an animal reservoir that is usually mammalian and sometimes avian. Not all zoonotic viruses are transmissible (directly or by an arthropod vector) between human hosts. Virus genome sequence data provide the best evidence of transmission. Of human transmissible virus, 37 species have so far been restricted to self-limiting outbreaks. These viruses are priorities for surveillance because relatively minor changes in their epidemiologies can potentially lead to major changes in the threat they pose to public health. On the basis of comparisons across all recognized human viruses, we consider the characteristics of these priority viruses and assess the likelihood that they will further emerge in human populations. We also assess the likelihood that a virus that can infect humans but is not capable of transmission (directly or by a vector) between human hosts can acquire that capability.

Quantitative risk assessment of WSSV transmission through partial harvesting and transport practices for shrimp aquaculture in Mexico

This quantitative risk assessment provided an analytical framework to estimate white spot syndrome virus (WSSV) transmission risks in the following different scenarios: (1) partial harvest from rearing ponds and (2) post-harvest transportation, assuming that the introduction of contaminated water with viral particles into shrimp culture ponds is the main source of viral transmission risk. Probabilities of infecting shrimp with waterborne WSSV were obtained by approaching the functional form that best fits (likelihood ratio test) published data on the dose-response relationship for WSSV orally inoculated through water into shrimp. Expert opinion defined the ranges for the following uncertain factors: (1) the concentrations of WSSV in the water spilled from the vehicles transporting the infected shrimp, (2) the total volume of these spills, and (3) the dilution into culture ponds. Multiple scenarios were analysed, starting with a viral load (VL) of 1×10²mL^-1 in the contaminated water spilled that reached the culture pond, whose probability of infection of an individual shrimp (P_i) was negligible (1.7×10^-7). Increasing the VL to 1×10^4.5mL^-1 and 1×10⁷mL^-1 yielded results into very low (P_i=5.3×10^-5) and high risk (P_i=1.6×10^-2) categories, respectively. Furthermore, different pond stocking density (SD) scenarios (20 and 30 post-larvae [PL]/m²) were evaluated, and the probability of infection of at least one out of the total number of shrimp exposed (P_N) was derived; for the scenarios with a low VL (1×10²mL^-1), the P_N remained at a negligible risk level (P_N, 2.4×10^-7 to 1.8×10^-6). For most of the scenarios with the moderate VL (1×10^4.5mL^-1), the P_N scaled up to a low risk category (P_N, 1.1×10^-4 to 5.6×10^-4), whereas for the scenarios with a high VL (1×10⁷mL^-1), the risk levels were high (P_N, 2.3×10^-2 to 3.5×10^-2) or very high (P_N, 1.1×10^-1 to 1.6×10^-1) depending on the volume of contaminated water spilled in the culture pond (VCWSCP, 4 or 20L). In the sensitivity analysis, for a SD of 30 PL/m², it was shown that starting with a VL of 1×10⁵mL^-1 and a VCWSCP of 12L, the P_N was moderate (1.05×10^-3). This was the threshold for greater risks, given the increase in either the VCWSCP or VL. These findings supported recommendations to prevent WSSV spread through more controlled transportation and partial harvesting practices.

Susceptibility of a number of Australian freshwater fishes to dwarf gourami iridovirus (Infectious spleen and kidney necrosis virus)

Megalocytiviruses cause high mortality diseases that have seriously impacted aquaculture, with the most frequent outbreaks occurring in East and South-East Asia. The international trade of juvenile fish for food and ornamental aquaculture has aided the spread of these viruses, which have spread to Europe and Australia and other regions. Australian freshwater fishes were examined for susceptibility to infection with the exotic megalocytivirus, dwarf gourami iridovirus (DGIV), which belongs to a group with the type species, Infectious spleen and kidney necrosis virus (ISKNV). Fish were held at 23 ± 1 °C and challenged by intraperitoneal (IP) injection or by cohabitation with Murray cod, Maccullochella peelii (Mitchell) infected with DGIV. A species was deemed to be susceptible to DGIV based on evidence of viral replication, as determined by qPCR, and megalocytic inclusion bodies observed histologically. Horizontal transmission occurred between infected Murray cod and golden perch, Macquaria ambigua (Richardson), Macquarie perch, Macquaria australasica (Cuvier) and Murray cod. This indicated that DGIV shed from infected fish held at 23 °C can survive in fresh water and subsequently infect these naïve fish. Further, DGIV administered IP was highly pathogenic to golden perch, Macquarie perch and Murray cod. Compared to these species, the susceptibility of southern pygmy perch, Nannoperca australis (Gunther) was lower. Freshwater catfish (dewfish), Tandanus tandanus (Mitchell), were not susceptible under the experimental conditions based on the absence of clinical disease, mortality and virus replication. This study showed the potential risks associated with naïve and DGIV-infected fish sharing a common water source.

Experimental Transmission and Induction of Ranaviral Disease in Western Ornate Box Turtles (Terrapene ornata ornata) and Red-Eared Sliders (Trachemys scripta elegans)

An experimental transmission study was designed to determine whether a causal relationship exists between a Ranavirus (BSTRV) isolated from a Burmese star tortoise that died and the lesions observed in that tortoise. A pilot study was performed with 3 box turtles ( Terrapene ornata ornata) and 3 red-eared sliders (RESs; Trachemys scripta elegans) to assess their suitability in a larger study. Based on the outcome of this study, RESs were selected, and 2 groups of 4 RESs received either an oral (PO) or intramuscular (IM) inoculum containing105 50% Tissue Culture Infecting Dose (TCID50) of a BSTRV-infected cell lysate. One turtle each was mock inoculated PO or IM with the same volume of uninfected cell lysate. Three of four IM-inoculated RESs developed clinical signs (nasal and ocular discharge [3 of 3], oral plaques [1 of 3], conjunctivitis and hyphema [1 of 3] and extreme lethargy [3 of 3]). A Ranavirus was isolated from kidney homogenates of 3 euthanatized turtles; DNA sequences of a portion of the major capsid protein gene were amplified by polymerase chain reaction. Consistent histologic lesions were observed only in IM-inoculated turtles and included fibrinoid vasculitis centered on splenic ellipsoids, multifocal hepatic necrosis, and multicentric fibrin thrombi in a variety of locations, including hepatic sinusoids, glomerular capillary loops, and pulmonary capillaries. Virions compatible with Ranavirus were observed within necrotic cells of the spleen of 1 IM-inoculated turtle using transmission electron microscopy. This study fulfills Koch's postulates, confirming a causal relationship between BSTRV and the clinical and histologic changes in chelonians infected with this virus.

Mosquitoes as a Potential Vector of Ranavirus Transmission in Terrestrial Turtles

Ranaviruses are significant pathogens of amphibians, reptiles, and fishes, contributing to mass mortality events worldwide. Despite an increasing focus on ranavirus ecology, our understanding of ranavirus transmission, especially among reptilian hosts, remains limited. For example, experimental evidence for oral transmission of the virus in chelonians is mixed. Consequently, vector-borne transmission has been hypothesized in terrestrial turtle species. To test this hypothesis, mosquitoes captured during a 2012/2013 ranavirus outbreak in box turtles from southwestern Indiana were pooled by genus and tested for ranavirus DNA using qPCR. Two of 30 pools tested positive for ranavirus. Additionally, an individual Aedes sp. mosquito observed engorging on a box turtle also tested positive for ranavirus. Although our approach does not rule out the possibility that the sequenced ranavirus was simply from virus in bloodmeal, it does suggests that mosquitoes may be involved in virus transmission as a mechanical or biological vector among ectothermic vertebrates. While additional studies are needed to elucidate the exact role of mosquitoes in ranavirus ecology, our study suggests that a greater focus on vector-borne transmission may be necessary to fully understand ranaviral disease dynamics in herpetofauna.

Isolation and characterization of a ranavirus from koi, Cyprinus carpio L., experiencing mass mortalities in India

We investigated mass mortalities of koi, Cyprinus carpio Linnaeus, 1758, experienced in South Indian fish farms by virus isolation, electron microscopy, PCR detection, sequencing of capsid protein gene and transmission studies. Samples of moribund koi brought to the laboratory suffered continuous mortality exhibiting swimming abnormalities, intermittent surfacing and skin darkening. Irido-like virus was isolated from the infected fish in the indigenous snakehead kidney cell line (SNKD2a). Icosahedral virus particles of 100 to 120 nm were observed in the infected cell cultures, budding from the cell membrane. Virus transmission and pathogenicity studies revealed that horizontal transmission occurred associated with mortality. PCR analysis of infected fish and cell cultures confirmed the presence of Ranavirus capsid protein sequences. Sequence analysis of the major capsid protein gene showed an identity of 99.9% to that of largemouth bass virus isolated from North America. Detection and successful isolation of this viral agent becomes the first record of isolation of a virus resembling Santee-Cooper Ranavirus from a koi and from India. We propose the name koi ranavirus to this agent.

Detection and characterization of viruses of the genus Megalocytivirus in ornamental fish imported into an Australian border quarantine premises: an emerging risk to national biosecurity

This report documents an emerging trend of identification of Megalocytivirus-like inclusions in a range of ornamental fish species intercepted during quarantine detention at the Australian border. From September 2012 to February 2013, 5 species of fish that had suffered mortality levels in excess of 25% whilst in the post-entry quarantine and had Megalocytivirus-like inclusion bodies in histological sections were examined by PCR. The fish had been imported from Singapore, Malaysia and Sri Lanka. Ninety-seven of 111 individual fish from affected tanks of fish tested were positive for the presence of Megalocytivirus by PCR. Sequence analysis of representative PCR products revealed an identical sequence of 621 bp in all cases which was identical to a previously characterized Megalocytivirus (Sabah/RAA1/2012 strain BMGIV48). Phylogenetic analysis of available Megalocytivirus major capsid protein (MCP) sequences confirmed the existence of 3 major clades of Megalocytivirus. The virus detected in this study was identified as a member of Genotype II. The broad host range and pathogenicity of megalocytiviruses, coupled to the documented spread of ornamental fish into the environment, render this a significant and emerging biosecurity threat to Australia.

Oysters as hot spots for mimivirus isolation

Viruses are ubiquitous organisms, but their role in the ecosystem and their prevalence are still poorly understood. Mimiviruses are extremely complex and large DNA viruses. Although metagenomic studies have suggested that members of the family Mimiviridae are abundant in oceans, there is a lack of information about the association of mimiviruses with marine organisms. In this work, we demonstrate by molecular and virological methods that oysters are excellent sources for mimiviruses isolation. Our data not only provide new information about the biology of these viruses but also raise questions regarding the role of oyster consumption as a putative source of mimivirus infection in humans.

Transmission of lymphocystis disease virus to cultured gilthead seabream, Sparus aurata L., larvae

The transmission of lymphocystis disease virus (LCDV) to gilthead seabream, Sparus aurata L., larvae was investigated using fertilized eggs from a farm with previous reports of lymphocystis disease. LCDV genome was detected by PCR-hybridization in blood samples from 17.5% of the asymptomatic gilthead seabream broodstock analysed. Using the same methodology, eggs spawned from these animals were LCDV positive, as well as larvae hatched from them. The presence of infective viral particles was confirmed by cytopathic effects development on SAF-1 cells. Whole-mount in situ hybridization (ISH) and immunohistochemistry (IHC) showed the presence of LCDV in the epidermis of larvae hatched from LCDV-positive eggs. When fertilized eggs were disinfected with iodine, no viral DNA was detected either in eggs (analysed by PCR-hybridization) or in larvae (PCR-hybridization and ISH). These results suggest the vertical transmission of LCDV, the virus being transmitted on the egg surface. Larvae hatched from disinfected eggs remain LCDV negative during the endotrophic phase, as showed by PCR-hybridization, ISH and IHC. After feeding on LCDV-positive rotifers, viral antigens were observed in the digestive tract, which suggests that viral entry could be achieved via the alimentary canal, and that rotifers can act as a vector in LCDV transmission to gilthead seabream larvae.

Do wild fish species contribute to the transmission of koi herpesvirus to carp in hatchery ponds?

The koi herpesvirus (KHV) has spread worldwide since its discovery in 1998 and causes disease and mortality in koi and common carp populations with a high impact on the carp production industry. Many investigations have been conducted to examine ways of distribution and to identify possible transmission vectors. The answers, however, raise many new questions. In the present study, different wild fish species taken from carp ponds with a history of KHV infection were examined for their susceptibility to the virus. In the tissue of these fish, the virus load was determined and it was tested whether a release of the virus could be induced by stress and the virus then could be transferred to naive carp. Wild fish were gathered from carp ponds during acute outbreaks of virus-induced mortality in summer and from ponds stocked with carp carrying a latent KHV infection. From these ponds, wild fish were collected during the harvesting process in autumn or spring when the ponds were drained. We found that regardless of season, temperature variation, age and infection status of the carp stock, wild fish from carp ponds and its outlets could be tested positive for the KHV genome using real-time PCR with a low prevalence and virus load. Furthermore, virus transfer to naive carp was observed after a period of cohabitation. Cyprinid and non-cyprinid wild fish can therefore be considered as an epidemiological risk for pond carp farms.

A DNA virus of Drosophila

Little is known about the viruses infecting most species. Even in groups as well-studied as Drosophila, only a handful of viruses have been well-characterized. A viral metagenomic approach was used to explore viral diversity in 83 wild-caught Drosophila innubila, a mushroom feeding member of the quinaria group. A single fly that was injected with, and died from, Drosophila C Virus (DCV) was added to the sample as a control. Two-thirds of reads in the infected sample had DCV as the best BLAST hit, suggesting that the protocol developed is highly sensitive. In addition to the DCV hits, several sequences had Oryctes rhinoceros Nudivirus, a double-stranded DNA virus, as a best BLAST hit. The virus associated with these sequences was termed Drosophila innubila Nudivirus (DiNV). PCR screens of natural populations showed that DiNV was both common and widespread taxonomically and geographically. Electron microscopy confirms the presence of virions in fly fecal material similar in structure to other described Nudiviruses. In 2 species, D. innubila and D. falleni, the virus is associated with a severe (∼80-90%) loss of fecundity and significantly decreased lifespan.

Pathogen host switching in commercial trade with management recommendations

Global wildlife trade exacerbates the spread of nonindigenous species. Pathogens also move with hosts through trade and often are released into naïve populations with unpredictable outcomes. Amphibians are moved commercially for pets, food, bait, and biomedicine, and are an excellent model for studying how wildlife trade relates to pathogen pollution. Ranaviruses are amphibian pathogens associated with annual population die-offs; multiple strains of tiger salamander ranaviruses move through the bait trade in the western United States. Ranaviruses infect amphibians, reptiles, and fish and are of additional concern because they can switch hosts. Tiger salamanders are used as live bait for freshwater fishing and are a potential source for ranaviruses switching hosts from amphibians to fish. We experimentally injected largemouth bass with a bait trade tiger salamander ranavirus. Largemouth bass became infected but exhibited no signs of disease or mortality. Amphibian bait ranaviruses have the potential to switch hosts to infect fish, but fish may act as dead-end hosts or nonsymptomatic carriers, potentially spreading infection as a result of trade.

Iridovirus infections in finfish - critical review with emphasis on ranaviruses

Viruses in three genera of the family Iridoviridae (iridoviruses) affect finfish. Ranaviruses and megalocytiviruses are recently emerged pathogens. Both cause severe systemic disease, occur globally and affect a diversity of hosts. In contrast, lymphocystiviruses cause superficial lesions and rarely cause economic loss. The ranavirus epizootic haematopoietic necrosis virus (EHNV) from Australia was the first iridovirus to cause epizootic mortality in finfish. Like other ranaviruses, it lacks host specificity. A distinct but closely related virus, European catfish virus, occurs in finfish in Europe, while very similar ranaviruses occur in amphibians in Europe, Asia, Australia, North America and South America. These viruses can be distinguished from one another by conserved differences in the sequence of the major capsid protein gene, which informs policies of the World Organisation for Animal Health to minimize transboundary spread of these agents. However, limited epidemiological information and variations in disease expression create difficulties for design of sampling strategies for surveillance. There is still uncertainty surrounding the taxonomy of some putative ranaviruses such as Singapore grouper iridovirus and Santee-Cooper ranavirus, both of which cause serious disease in fish, and confusion continues with diseases caused by megalocytiviruses. In this review, aspects of the agents and diseases caused by ranaviruses are contrasted with those due to megalocytiviruses to promote accurate diagnosis and characterization of the agents responsible. Ranavirus epizootics in amphibians are also discussed because of possible links with finfish and common anthropogenic mechanisms of spread. The source of the global epizootic of disease caused by systemic iridoviruses in finfish and amphibians is uncertain, but three possibilities are discussed: trade in food fish, trade in ornamental fish, reptiles and amphibians and emergence from unknown reservoir hosts associated with environmental change.

Analysis of the entire genomes of torque teno midi virus variants in chimpanzees: infrequent cross-species infection between humans and chimpanzees

Humans are frequently infected with three anelloviruses which have circular DNA genomes of 3.6-3.9 kb [Torque teno virus (TTV)], 2.8-2.9 kb [Torque teno mini virus (TTMV)] and 3.2 kb [a recently discovered anellovirus named Torque teno midi virus (TTMDV)]. Unexpectedly, human TTMDV DNA was not detectable in any of 74 chimpanzees tested, although all but one tested positive for both human TTV and TTMV DNA. Using universal primers for anelloviruses, novel variants of TTMDV that are phylogenetically clearly separate from human TTMDV were identified from chimpanzees, and over the entire genome, three chimpanzee TTMDV variants differed by 17.9-20.3 % from each other and by 40.4-43.6 % from all 18 reported human TTMDVs. A newly developed PCR assay that uses chimpanzee TTMDV-specific primers revealed the high prevalence of chimpanzee TTMDV in chimpanzees (63/74, 85 %) but low prevalence in humans (1/100). While variants of TTV and TTMV from chimpanzees and humans were phylogenetically interspersed, those of TTMDV were monophyletic for each species, with sequence diversity of <33 and <20 % within the 18 human and three chimpanzee TTMDV variants, respectively. Maximum within-group divergence values for TTV and TTMV were 51 and 57 %, respectively; both of these values were substantially greater than the maximum divergence among TTMDV variants (44 %), consistent with a later evolutionary emergence of TTMDV. However, substantiation of this hypothesis will require further analysis of genetic diversity using an expanded dataset of TTMDV variants in humans and chimpanzees. Similarly, the underlying mechanism of observed infrequent cross-species infection of TTMDV between humans and chimpanzees deserves further analysis.

Amphibian commerce as a likely source of pathogen pollution

The commercial trade of wildlife occurs on a global scale. In addition to removing animals from their native populations, this trade may lead to the release and subsequent introduction of nonindigenous species and the pathogens they carry. Emerging infectious diseases, such as chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), and ranaviral disease have spread with global trade in amphibians and are linked to amphibian declines and die-offs worldwide, which suggests that the commercial trade in amphibians may be a source of pathogen pollution. We screened tiger salamanders involved in the bait trade in the western United States for both ranaviruses and Bd with polymerase chain reaction and used oral reports from bait shops and ranavirus DNA sequences from infected bait salamanders to determine how these animals and their pathogens are moved geographically by commerce. In addition, we conducted 2 surveys of anglers to determine how often tiger salamanders are used as bait and how often they are released into fishing waters by anglers, and organized bait-shop surveys to determine whether tiger salamanders are released back into the wild after being housed in bait shops. Ranaviruses were detected in the tiger salamander bait trade in Arizona, Colorado, and New Mexico, and Bd was detected in Arizona bait shops. Ranaviruses were spread geographically through the bait trade. All tiger salamanders in the bait trade were collected from the wild, and in general they moved east to west and north to south, bringing with them their multiple ranavirus strains. Finally, 26-73% of anglers used tiger salamanders as fishing bait, 26-67% of anglers released tiger salamanders bought as bait into fishing waters, and 4% of bait shops released tiger salamanders back into the wild after they were housed in shops with infected animals. The tiger salamander bait trade in the western United States is a useful model for understanding the consequences of the unregulated anthropogenic movement of amphibians and their pathogens through trade.

Transmission dynamics of the amphibian ranavirus Ambystoma tigrinum virus

Transmission is central to pathogen fitness and strongly influences the impact of pathogens on host populations. Particularly important to transmission dynamics is the distinction between direct transmission requiring close physical contact (e.g. bumping, fighting, or coughing) and indirect transmission from environmental sources such as contaminated substrates. We present data from 4 experiments addressing the form, routes, and timing of transmission of Ambystoma tigrinum virus (ATV) among tiger salamanders Ambystoma tigrinum nebulosum. Our data suggest that ATV is efficiently transmitted by direct interactions between live animals (bumping, biting and cannibalism) as well as by necrophagy and indirectly via water and fomites. Determining which form of transmission is most important in nature is essential for understanding transmission at the population level. Our experiments also revealed an important temporal aspect of infectiousness: larval salamanders become infectious soon after exposure to ATV and their propensity to infect others increases with time. These results begin to clarify the mechanisms and dynamics of ATV transmission and lead to key questions that need to be addressed in future research.

Phylogenetic concordance analysis shows an emerging pathogen is novel and endemic

Distinguishing whether pathogens are novel or endemic is critical for controlling emerging infectious diseases, an increasing threat to wildlife and human health. To test the endemic vs. novel pathogen hypothesis, we present a unique analysis of intraspecific host-pathogen phylogenetic concordance of tiger salamanders and an emerging Ranavirus throughout Western North America. There is significant non-concordance of host and virus gene trees, suggesting pathogen novelty. However, non-concordance has likely resulted from virus introductions by human movement of infected salamanders. When human-associated viral introductions are excluded, host and virus gene trees are identical, strongly supporting coevolution and endemism. A laboratory experiment showed an introduced virus strain is significantly more virulent than endemic strains, likely due to artificial selection for high virulence. Thus, our analysis of intraspecific phylogenetic concordance revealed that human introduction of viruses is the mechanism underlying tree non-concordance and possibly disease emergence via artificial selection.

SEN virus co-infection among HCV-RNA-positive mothers, risk of transmission to the offspring and outcome of child infection during a 1-year follow-up

SEN is a newly discovered blood-transmissible virus. Among its variants, SENV-D and -H are most often associated with non-A, -E hepatitis. Very little is known about the risk of vertical transmission of the virus. By using polymerase chain reaction with specific primers for SENV-D and -H, we investigated the prevalence of SENV-H and -D infection, the transmission rate of SENV infection and clinical features of SENV-infected children in 89 hepatitis C virus (HCV)-positive human immunodeficiency virus type 1-negative mothers. SENV infection was found in 36 (40%) mothers, and SENV-D was more frequent than SENV-H infection (34/36, 94%vs 5/36, 14%, P < 0.01). No difference in SENV infection rates was found between injection drug user (IDU) mothers (17/51, 33%) and mothers with no risk for bloodborne infection (19/38, 50%, P = ns). SENV-H infection was found only in IDU mothers and mothers with HCV genotype1b. Both SENV-D and -H can be transmitted to the offspring with an overall rate of 47%. Vertical transmission of HCV does not facilitate SENV infection of the offspring. Among 17 SENV-infected children, none was co-infected with HCV. Maternal HCV genotype or viral load does not interfere with mother-to-infant transmission of SENV. Persistence of SENV infection was demonstrated in 100% of infected children after 1-year follow-up, but none had clinical evidence of liver disease.

Experimental transmission of a ranavirus disease of common toads (Bufo bufo) to common frogs (Rana temporaria)

During investigations of epidemic frog mortality in Britain, a novel fatal systemic haemorrhagic disease of common toads was discovered. This disease resembles a systemic haemorrhagic disease of common frogs in Britain, which is one of a range of fatal disease syndromes, characterized by systemic haemorrhages, skin ulceration or a combination of these lesions, caused by ranavirus infection. Ranavirus previously isolated from diseased toads was inoculated into common frogs to evaluate if this virus could infect and cause disease in common frogs. All virus-inoculated frogs died with systemic haemorrhages between 6 and 8 days post-inoculation, giving similar results to those produced by the inoculation of frogs with ranavirus cultured from naturally diseased frogs. These results indicate that the same, or similar, viruses are affecting both frogs and toads in the field and confirm that ranavirus has emerged as an important cause of amphibian mortality in Britain.

[Investigation of transplacental transmission of TT virus in mother--newborn pairs]

TT virus (TTV) is widespread throughout the world and can be detected in 50-95% of healthy individuals. However, in chronic hepatitis C virus (HCV) infected patients coinfected with TTV, histological activity indices were higher than patients with HCV infection alone. There are studies which indicate that TTV can cause aplastic anemia and thrombocytopenia. While TTV is known to be transmitted through blood transfusions and by fecal-oral route, published information on transplasental transmission is controversial. The aims of this study were to detect the frequency of TTV infection among healthy pregnant women and to search whether TTV is transmitted transplasentally during pregnancy. For this purpose, plasma samples collected from 54 women and their newborns were investigated by polymerase chain reaction (PCR), and viral loads were determined for infected newborns, and their respective mothers. Also, ten mothers whose newborns were tested negative for TTV-DNA were enrolled in viral load tests for comparison. TTV-DNA was detected in 49 (90.7%) of 54 women. Of 49 newborns whose mothers were infected with TTV, only 4 (8.2%) were found positive for TTV-DNA. There was no statistically significant difference in TTV-DNA loads between mothers who transmitted the virus and those who did not (Mann-Whitney U analysis Z=-0.071, P=0.944). As a result, transplasental transmission of TTV is possible but occurs in low frequency and independent of viral load.

Ranavirus in wood frogs (Rana sylvatica): potential sources of transmission within and between ponds

Members of the genus Ranavirus (family Iridoviridae) can cause catastrophic mortality of pond-breeding amphibians and are associated with an emerging infectious disease that may be contributing to amphibian declines. We conducted three experiments to examine factors that may affect transmission both within and between local breeding populations of the wood frog (Rana sylvatica). In a laboratory study, when exposed to moribund tadpoles collected during a local ranaviral die-off, uninfected tadpoles died as soon as 4 days after exposure. The onset of death was accelerated when tadpoles were allowed to scavenge on carcasses of infected tadpoles. In a mesocosm experiment that was conducted in outdoor wading pools, die-offs of tadpoles began approximately 19 days after infected tadpoles were added to pools containing uninfected tadpoles. Mass die-offs with greater than 98% mortality occurred in all pools, regardless of the initial tadpole density. In a second mesocosm experiment, the addition of water and bottom sediments that were collected from a pond during a ranaviral die-off did not result in lower tadpole survival or growth relative to controls. Only a small percentage of tadpoles appeared to be sick, and most tadpoles survived until the first individuals began metamorphosing within a pool. However, tests for ranavirus using polymerase chain reaction were positive for most pools that received contaminated sediment, suggesting that some infections were sublethal. Our results indicate that transmission within ponds is enhanced by scavenging and that spread between local ponds could occur via the transport of contaminated sediment by animals or humans.

Transfusion transmitted virus: A review on its molecular characteristics and role in medicine

The present review gives an updated overview of transfusion transmitted virus (TTV), a novel agent, in relation to its molecular characteristics, epidemiological features, modes of transmission, tissue tropism, pathogenesis, role in various diseases and its eradication from the body. TTV, a DNA virus, is a single stranded, non-enveloped, 3.8 kb long DNA virus with a small and covalently closed circular genome comprising 3852 bases. It was tentatively designated Circinoviridae virus. TTV genome sequence is heterogeneous and reveals the existence of six different genotypes and several subtypes. TTV has been reported to transmit not only via parenteral routes, but also via alternate routes. This virus has been detected in different non-human primates as well. At present, TTV is detected by polymerase chain reaction (PCR) with no other available diagnostic assays. It shows its presence globally and was detected in high percent populations of healthy persons as well as in various disease groups. Initially it was supposed to have strong association with liver disease; however, there is little evidence to show its liver tropism and contribution in causing liver diseases. It shows high prevalence in hemodialysis patients, pointing towards its significance in renal diseases. In addition, TTV is associated with several infectious and non-infectious diseases. Although its exact pathogenesis is not yet clear, TTV virus possibly resides and multiplies in bone marrow cells and peripheral blood mononuclear cells (PBMCs). Recently, attempts have been made to eradicate this virus with interferon treatment. More information is still needed to extricate various mysteries related to TTV.

Transmission of white sturgeon iridovirus in Kootenai River white sturgeon Acipenser transmontanus

It is thought that white sturgeon iridovirus (WSIV) is transmitted vertically from adult white sturgeon Acipenser transmontanus to progeny, and that wild adults are carriers of this virus. Based on this assumption, egg disinfection trials were initiated using wild Kootenai River white sturgeon. Over 2 consecutive years, post-fertilized eggs were disinfected with iodine at concentrations ranging from 0 to 400 ppm. Eggs were incubated and progeny were reared on either de-chlorinated municipal or Kootenai River water. Juvenile sturgeon (mean weight 3.0 g) from these treatment groups were then subjected to a density stress (15 or 20 g(-1)) to manifest WSIV disease in individuals harboring the virus. In Year 1, mortality in all groups ranged from 6 to 37% and the use of municipal water was shown to significantly improve survival. However, WSIV infection was not detected in fish from any of the treatment groups or controls, and therefore did not contribute to the observed mortality. In Year 2, all treatment and control groups reared on Kootenai River water tested positive for WSIV infection and exhibited mortality ranging from 59 to 94%, but fish from groups reared on municipal water did not test positive for WSIV infection. This shows that that vertical transmission did not occur in this study. Horizontal transmission played a significant role in WSIV infection, but the lack of infection in Year 1 suggests a cyclic occurrence of the virus in the Kootenai River system. Although survival tended to be better in iodine-treated groups, the effects of iodine treatment in relation to WSIV transmission remain unknown. An important finding is that not all wild white sturgeon broodstock yield WSIV-positive progeny.

SEN virus infection in children in Taiwan: transmission route and role in blood transfusion and liver diseases

BACKGROUND

SEN virus (SENV) is a newly discovered DNA virus. We conducted this study to evaluate potential modes of SENV transmission and the pathogenic effect of SENV on liver diseases in children.

METHODS

Polymerase chain reaction was used to detect 2 SENV variant (SENV-D and SENV-H) DNA in sera from healthy individuals and diseased children. Nucleotide sequence of SENV was determined by direct sequencing.

RESULTS

SENV infection was assessed in healthy individuals, including 50 newborns (sera collected from the umbilical cord), 24 infants, 46 preschool children (aged 1-6 years), 42 school children of an age before that of the first sexual experience (aged 7-12 years), 62 adolescents (13-18 years), 72 young adults (19-30 years) and 32 adults (>30 years). The prevalence of SENV-D and/or SENV-H (SENV-D/H) viremia in each group was 0%, 17%, 24%, 24%, 27%, 33% and 40%, respectively. The prevalence of SENV-D/H viremia in 18 children with non-A to E hepatitis, 64 thalassemic children, 80 children transfused during cardiac surgery, 30 children with chronic hepatitis B, 9 children with chronic hepatitis C and 32 infants with biliary atresia was 11%, 61%, 80%, 83%, 67% and 50%, respectively. SENV was found more frequently in all patient groups than in 174 age-matched controls (P < 0.01), with the exception of non-A to E hepatitis (11% versus 24% in the control group; P = 0.27). In 2 infants with proven intrauterine hepatitis B viral infection, identical SENV-D nucleotide sequence existed in both the maternal and neonate serum. Elevated alanine aminotransferase concentrations were rarely observed in children who acquired isolated SENV viremia because of transfusion for surgery. Infection with SENV in children with chronic hepatitis C virus or hepatitis B viral infection was not associated with higher peak alanine aminotransferase values.

CONCLUSION

SENV is transmitted mainly via nonparenteral daily contact and frequently occurs early in life. Transfusion can significantly increase the rate of SENV viremia. SENV does not appear to cause hepatitis in children.

Transfusion transmitted virus in screened United Arab Emirates blood donors

OBJECTIVE

To investigate the rate of infection caused by Torque teno virus (TTV) in United Arab Emirates (UAEs) healthy population as a pilot study in detecting TTV DNA in 100 healthy blood donors.

METHODS

We randomly choose a total of 100 healthy blood donors who attended Zayed Military Hospital, Abu Dhabi, UAE from January 20 to May 30, 2005. We carried out a real-time polymerase chain reaction (PCR) test to detect TTV DNA.

RESULTS

Real-time for TTV was positive in 75 (75%) donors. Eight (73%) non-UAE donors were TTV positive while 67 (75%) were UAEs. Among these donors, 72 (77%) were males and 3 (50%) were females.

CONCLUSION

Our results demonstrated a high prevalence of TTV in UAE.

[Investigation of SEN virus genotypes D and H among blood donors in Mersin University Medical School Hospital]

SEN virus is a recently discovered DNA virus, and eight genotypes (A to H) were detected by phylogenetic analysis. Genotype D (SENV-D) and H (SENV-H) are thought to be associated in the etiology of post-transfusion hepatitis. Although no strong association was revealed between liver pathology and SEN virus, the viral replication in hepatocytes and transmission by blood transfusions were well characterized. The aim of this study was to investigate the prevalence of SENV-D and SENV-H in blood donors. One hundred serum samples were included in the study which were obtained from blood donors comprised of 98 male and 2 female with a mean age 36.4 years who were enrolled at Mersin University Faculty of Medicine blood center. The DNAs of SENV-D and SENV-H were detected with polymerase chain reaction (PCR), by using D10S/L2AS and C5S/L2AS primers, respectively. SEN virus DNA positivity was detected in 25 of 100 (25%) sera, of which 10 (10%) were positive for SENV-D and 15 (15%) were positive for SENV-H DNA. Although, the number of samples were not sufficient to reflect the general prevalence, our study relatively reveals that asymptomatic carriage rate of these viruses were 25% in our province.

Prevalence, epidemiological aspects and clinical importance of TT virus infection in Slovakia

The aim of the study was to assess the prevalence, clinical impact and importance of different risk factors of transmission of TTV infection in Slovakia using two PCR methods. Sera of 426 adult persons were examined. TTV DNA was identified by PCR using primers from N22 and untranslated region (UTR) respectively. The established prevalence of TTV tested with N22 and UTR primers according to patients groups was: acute hepatitis of unknown etiology 4 resp. 28 of 37, acute hepatitis B 3 resp. 29 of 38, chronic hepatitis B 11 resp. 41 of 44, chronic hepatitis C 10 resp. 93 of 102, hemodialysis patients 13 resp. 72 of 72, health care workers 0 resp. 27 of 33, control group 8 resp. 83 of 100. Using N22 primers, TTV infection occurred more frequently in chronic hepatitis B group compared with health care workers, if UTR primers were used the group of hemodialysis patients differed significantly from both acute hepatitis groups, health care workers and controls (p < 0.05). From possible risk factors hemodialysis and transfusion count showed notable differences. Bilirubin and aminotransferase levels did not differ between TTV positive and negative groups. No pathogenetic role of TT virus in liver injury was confirmed.

Prevalence of transfusion-transmitted virus infection in patients on maintenance hemodialysis from New Delhi, India

Transfusion-transmitted virus (TTV) has been reported from a number of hemodialysis (HD) units from various countries throughout the world. TTV has been associated with liver diseases, viral hepatitis B, and C. Clinical details and information regarding TTV prevalence from India are insufficient. The prevalence and clinical significance of TTV infection were studied in New Delhi, India in HD patients. Serum samples were derived from 75 patients on maintenance HD, and 75 age- and sex-matched voluntary blood donors were examined for TTV viremia by nested polymerase chain reaction (PCR) using primers derived from UTR (A) region of the TTV genome. The prevalence of TTV DNA in patients on HD (83%) was significantly (p<0.05) higher than in blood donors (43%). Clinical background including the mean age, sex, mean duration of HD, and mean alanine aminotransferase (ALT) levels did not differ significantly between TTV DNA-positive and -negative HD patients. Fifty-four (72%) TTV-positive HD patients and 7 (56%) TTV-negative HD patients had blood transfusion histories (p>0.05). Among TTV-positive patients, Hepatitis B virus (HBV) co-infection was present in 14.2% cases while hepatitis C virus (HCV) co-infection was absent. Persistent elevation of ALT levels was observed in 7(9.3%) HD patients; 3 (43%) of them were TTV positive and 4 (57%) were TTV negative (p>0.05). All 3 TTV-positive patients with elevated ALT levels were co-infected with HBV. Patients with TTV infection alone showed normal ALT levels. Prevalence of TTV infection is high in North Indian patients on maintenance HD. Also, none of the exclusively TTV DNA-positive patients had clinical or biochemical signs of liver disease. TTV seems to spread through parenteral routes. More often, TTV seems to be associated with parenterally transmitted virus HBV, indicating a parenteral mode of TTV transmission. The pathogenicity of TTV remains unclear from the present study.

SEN virus: epidemiology and characteristics of a transfusion-transmitted virus

SEN virus (SEN-V) is a blood-borne, single-stranded, nonenveloped DNA virus. Although its prevalence varies by geographic region, it has been detected in as many as 30 percent of postoperative transfusion recipients, compared to 3 percent of postoperative patients who did not receive transfusions. A significant association has been observed between transfusion volume and the occurrence of SEN-V infection. Transmission by transfusion also has been confirmed by the detection of greater than 99 percent homology between SEN-V in donor and recipient sera. Concurrent infections with SEN-V and hepatitis B virus, hepatitis C virus, or human immunodeficiency virus type 1 have been documented, and these observations probably reflect the blood-borne transmission of these viruses as well as SEN-V. Although SEN-V was discovered as part of a search for causes of posttransfusion hepatitis, there is no firm evidence so far that SEN-V infection either causes hepatitis or worsens the course of coexistent liver disease. Nevertheless, SEN-V appears to be transmitted by transfusion, and further studies may reveal more about its role in the future.

Mother-to-infant vertical transmission of transfusion transmitted virus in South China

A nested PCR was used to detect TTV DNA in serum from 490 mother-infant pairs to determine the rate of vertical transmission of TTV in Guangzhou City, P.R. China. TTV DNA was positive in 87 mothers and 12 of their babies, giving a prevalence of 17.8% in pregnant women and a mother-to-child transmission rate of 13.8%. In eight mother-infant pairs, TTV DNA nucleotide sequences from the mothers and their corresponding infants were identical. The homology of Guangzhou TTV and Japanese TTV ranged from 85.3%-98.2% at nucleotide level. TTV infection is common in pregnant women in South China and vertical transmission can occur. Guangzhou's and Japanese TTV isolates belong to the same genotype.

[Investigation of TT virus-DNA in multitransfused children and healthy children]

TT virus (TTV) is a naked, single stranded DNA virus, which has been discovered in the serum of a patient with posttransfusion hepatitis of unknown etiology. TTV is widespread in the population, however, the mode of its transmission is unclear. This study was conducted to search for TTV-DNA positivity rates and its relationship with the clinical outcomes of recipients who underwent multiple blood or blood product transfusion, together with healthy children. TTV-DNA was investigated in 52 multitransfused pediatric patients (age range: 3 mnths - 17.5 yrs, mean age: 9.2 +/- 5.7 years) and 18 healthy children (age range: 1 mnth - 16.5 yrs, mean age: 8.1 +/- 4.9 years), by qualitative in-house semi-nested polymerase chain reaction (PCR) with the primers NG059, NG061 and NG063, generated from ORF1 region of the viral genome. TTV-DNA was found positive in 30.8% of multitransfused, and 16.7% of healthy children. The differences of TTV-DNA positivity rates between the multitransfused and control groups, and ALT values between the patients with positive and negative TTV-DNA, were statistically insignificant (p>0.05). As a result, no relationship was detected between TTV positivity and hepatitis, although there was a statistically insignificant increase of TTV-DNA positivity in multitransfused children. However, since the primers of ORF1 N22 region used in our PCR method did not have enough sensitivity for the detection of TTV-DNA, it has been concluded that more sensitive primers such as UTR primers, should be used for more reliable evaluation of the results.

Vertical transmission of nucleopolyhedrovirus in the silkworm, Bombyx mori L

Nucleopolyhedrovirus (NPV) was tested for vertical transmission in the silkworm, Bombyx mori. Fifth instar larvae were exposed to four different dosages of BmNPV (830, 1300, 1800, and 2000OBs/larva) and a dosage of about 2000OBs/larva was found suitable for obtaining infected adults. Histopathological studies revealed the infection in susceptible tissues and organs initially, and at later stages of infection cycles the spermatocytes and nurse cells in the young oocytes were infected in the larval rudiments of testis and ovary, respectively. The mating of infected females with uninfected males resulted in significant reduction in fecundity (P < 0.01) and hatching of eggs (P < 0.001) due to transovarial transmission of BmNPV. Mating tests of uninfected females and infected males also confirmed venereal transmission as there was a significant reduction in hatching of eggs (P < 0.01). Further, among the F1 hybrid offspring (infected female x uninfected male) that were infected transovarially, larval progeny died at first and second instar stages, whereas those infected venereally developed acute lethal infection late and died by the end of third and fourth instar stage. PCR amplification and sequencing of 473bp of immediate early-1 (ie-1) gene of BmNPV isolated from the viral-infected parent and the F1 offspring confirmed that the viral infection is vertically transmitted to the progeny.

Age-specific prevalence, transmission and phylogeny of TT virus in the Czech Republic

Background

TT virus is prevalent worldwide, but its prevalence and genotype distribution in Central and East-Europe has not been determined. The high prevalence of TTV in multiply-transfused patients points to the importance of a parenteral mode of transmission, but since more than half of the general population is infected other possible routes of transmission must be considered.

Methods

In our study, we investigated the epidemiology, transmission and phylogeny of TTV in the Czech Republic. The following groups were selected: a control group of 196 blood donors, 20 patients with hemophilia, 49 intravenous drug users, 100 sex workers, 50 penitentiary prisoners, 208 healthy children aged 1 to 14 years, 54 cord blood samples, 52 patients with non-A-E hepatitis, 74 patients with hepatitis C, and 51 blood donors with increased ALT levels. Primers specific for the non-coding region were used. The genotype distribution was studied in 70 TTV-positive samples.

Results

The prevalence rate of TTV among the Czech population was 52.6%. We have shown that TTV is not transmitted prenatally. Children were infected after birth with two peaks: one at the age of two years and the other after the beginning of primary school. Adults have shown a further increase in the TTV prevalence with age. The highest TTV prevalence was found in the group of patients who had received multiple blood transfusions. The TTV prevalence rate in subjects at an increased risk of sexual transmission was not significantly higher than in the general population. Genotypes G2 and G1 were most prevalent among the Czech population, followed by G8 and G3. The subjects positive for markers of HBV and/or HCV infection tested significantly more often TTV DNA positive, which is suggestive of a common route of transmission of these three infections.

Conclusions

This study on TTV prevalence, mode of transmission and age-specific prevalence is the most extensive study performed in Central and Eastern Europe. It showed insights into the epidemiology of TTV infection, but failed to associate TTV infection with clinical manifestations.

TTV infection in children born to mothers infected with TTV but not with HBV, HCV, or HIV

The TT virus (TTV) was isolated recently from the serum of a patient with post-transfusion hepatitis. TTV infection is widespread in the general population, and its prevalence increases continuously with age. The pathogenic role of TTV in liver disease remains controversial, and the source of transmission is still unclear. We investigated the pathogenicity and epidemiology of TTV infection in infants born to TTV DNA-positive mothers. Enrolled in this study were 22 mother-child pairs testing negative for antibodies to hepatitis B, hepatitis C, and the human immunodeficiency viruses (HIVs). The children were followed for 30 months after birth. Serum TTV DNA was detected by N22-PCR, and the PCR products were cloned and sequenced. The prevalence of TTV infection in children increased with age. Of the 22 children, 13 (59%) became positive for TTV DNA during the follow-up period. Of these 13 children, 6 (46%) had elevated levels of serum alanine aminotransferase (ALT), although the elevations were transient and mild. TTV viremia was not associated significantly with the abnormal ALT levels. Children with TTV viremia developed neither severe liver disease nor fulminant hepatitis. Phylogenetic analysis showed that, in 11 (85%) of the 13 pairs, the mother and child had the same genotype at the first PCR-positive time point. Among those 11 mother-child pairs, 6 (55%) had identical TTV nucleotide sequences. However, the genotype of predominant clones changed in 5 (50%) of 10 children who were positive for TTV DNA at two or more time points during the follow-up period. In conclusion, this study did not provide evidence that TTV infection is related to liver disease in children. Although the main source of TTV infection in children is presumed to be their mothers, transmitted via non-parenteral routes in the course of daily contact, intrafamilial carriers may also be sources of TTV infection.

RESPONSE OF THE ITALIAN AGILE FROG (RANA LATASTEI) TO A RANAVIRUS, FROG VIRUS 3: A MODEL FOR VIRAL EMERGENCE IN NAÏVE POPULATIONS

Ranavirus (family Iridoviridae) is a genus of pathogens of poikilotherms, and some ranaviruses may play a role in widespread mortality of amphibians. Ecology of viral transmission in amphibians is poorly known but can be addressed through experimentation in the laboratory. In this study, we use the Ranavirus frog virus 3 (FV3) as an experimental model for pathogen emergence in naive populations of tadpoles. We simulated emerging disease by exposing tadpoles of the Italian agile frog (Rana latastei), to the North American Ranavirus FV3. We demonstrated that mortality occurred due to viral exposure, exposure of tadpoles to decreasing concentrations of FV3 in the laboratory produced dose-dependent survival rates, and cannibalism of virus-carrying carcasses increased mortality due to FV3. These experiments suggest the potential for ecological mechanisms to affect the level of exposure of tadpoles to Ranavirus and to impact transmission of viral pathogens in aquatic systems.

Helicobacter pylori and TT virus prevalence in Japanese children

BACKGROUND

The major transmission route of Helicobacter pylori, oral-oral or fecal-oral, remains to be established. TT virus (TTV), a recently discovered microbe that is prevalent in healthy persons, is believed to be mainly transmitted by nonparenteral routes. The purpose of this study was to test the hypothesis that these two microorganisms have a common mode of transmission.

METHODS

We investigated the seroprevalence of H. pylori and TTV in a cross-sectional study of 454 healthy Japanese children from birth to age 15 years, living in five different geographic areas. Determination of H. pylori status was based on the presence of specific serum IgG and IgA antibodies, determined using enzyme immunoassays. TTV DNA was detected and the titer was determined using semiquantitative polymerase chain reaction with heminested primers.

RESULTS

The overall prevalences of H. pylori and TTV were 12.2% and 21.6%, respectively. An age-related increase of prevalence was shown for H. pylori ( P < 0.001), but not for TTV ( P = 0.23). Titers of TTV DNA significantly decreased with age (P = 0.02). There were significant geographic differences in TTV prevalence ( P < 0.001), but not in H. pylori seroprevalence (P = 0.33). There was no true correlation between the prevalence of these two organisms (Phi coefficient = -0.02 and P = 0.66).

CONCLUSIONS

Although Japanese children frequently acquire both H. pylori and TTV, especially in early childhood, their acquisition appears to be independent.

Transfusional transmitted virus seroprevalence in asymptomatic HBsAg (+) hepatitis B carriers

BACKGROUND

The aim of this study was to evaluate the transfusional transmitted virus (TTV) seroprevalence in asymptomatic HBsAg (+) patients and to assess the influence of TTV on the course of these patients.

METHODS

Sixty asymptomatic HBV carriers were included and 31 healthy volunteers served as controls. Cases were followed at 6-month intervals for a total duration of 4 years.

RESULTS

In the asymptomatic carrier group, 31 patients (51.7%) had a history of surgery and 10 (16.7%) had a history of blood transfusions. TTV-DNA was detected in 45 of these patients (75%). In the control group, 12 patients (38.7%) had a history of surgery and 2 had (6.5%) a history of blood transfusions. TTV-DNA was found in 20 (64.5%) of these subjects. The incidence of TTV-DNA positivity was not significantly different between the two groups (P > 0.05).

CONCLUSION

In spite of the common occurrence of HBV and TTV, TTV-DNA was also detected in 64.5% of healthy controls. Furthermore, during 4 years of follow up, TTV had no detrimental effects on the course of asymptomatic HBV carriers. These results suggest that the hepatic injury due to TTV is insignificant in this group of patients.