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AI-enabled viral genomics: from virus discovery to host prediction and emerging variant forecasting.

The rapid expansion of metagenomic sequencing has generated vast repositories of viral sequence data that far outpace our capacity to interpret them using conventional approaches. Highly divergent sequences, sparse functional annotation, and taxonomically uneven sampling present fundamental challenges for reference-dependent methods, which lose sensitivity precisely for novel and understudied viruses with high public health relevance. Artificial intelligence (AI) provides a new avenue to address these challenges by enabling predictive inference from viral genomes and proteins while reducing dependence on sequence similarity. In this Review, we discuss representative advances in AI for virus discovery, taxonomic classification and functional annotation, prediction of host range and zoonotic potential, and efforts toward forecasting emerging variants. These advances are transforming viral genomics from a largely descriptive discipline into one with increasing predictive capability. We also critically assess the major challenges that constrain current approaches, including the availability of high-quality and representative datasets, rigorous model evaluation, biological interpretability and responsible governance for increasingly capable AI models.

Artificial Intelligence↗

The zoonotic transmission of Giardia and Cryptosporidium.

The molecular characterisation of Giardia and Cryptosporidium has given rise to a more epidemiological meaningful and robust taxonomy. Importantly, molecular tools are now available for 'typing' isolates of the parasites directly from clinical and environmental samples. As a consequence, information on zoonotic potential has been obtained although the frequency of zoonotic transmission is still poorly understood. Analysis of outbreaks and case-control studies, especially when coupled with genotyping data, is slowly providing information on the public health significance of zoonotic transmission. Such studies support the hypothesis that Cryptosporidium hominis is spread only between humans but that the major reservoir for Cryptosporidium parvum is domestic livestock, predominantly cattle, and that direct contact with infected cattle is a major transmission pathway along with indirect transmission through drinking water. The situation is less clearcut for Giardia duodenalis but the evidence does not, in general, support zoonotic transmission as a major risk for human infections. However, for both parasites there is a need for molecular epidemiological studies to be undertaken in well-defined foci of transmission in order to fully determine the frequency and importance of zoonotic transmission.

Animals↗

Zoonotic risk of Toxocara canis infection through consumption of pig or poultry viscera.

The potential zoonotic risk of Toxocara canis infections from consumption of swine or poultry viscera containing larvae was assessed using a pig model. Two groups of six pigs were fed either fresh swine viscera (group FS) or poultry viscera (FP) containing around 3500 Toxocara larvae. Another two groups of six pigs were fed swine viscera (PS) or poultry viscera (PP) preserved at 4 degrees C for 1 week. All pigs were necropsied 14 days after the exposure. Liver white spots were counted and T. canis specific IgG antibodies were measured by ELISA. Larval burdens were assessed in the mesenteric lymph nodes, liver, lungs, brain, tongue, and eyes. All recipient pigs exhibited several white spots on the liver surface and detectable antibody levels. Larvae were recovered predominantly from the lungs, but also from the mesenteric lymph nodes and the liver, a few larvae were found in the brain and tongue of the pigs. Two larvae were found in the eyes of two pigs in group FS. Mean percentages of total larval recoveries in groups FS, FP, PS, and PP were 75.3, 63.6, 42.6, and 18.8%, respectively. Significantly higher numbers of larvae were recovered from pigs given swine viscera than pigs given poultry viscera. The preservation at 4 degrees C for 1 week caused a significant reduction in the larval infectivity overall, nevertheless, the recoveries remained substantial. The fact that larvae migrating in swine or poultry organs and tissues have high infectivity in pigs even after preservation at 4 degrees C for 1 week, suggests that human infection with T. canis might easily occur following consumption of raw or undercooked dishes, either fresh or refrigerated, prepared from swine or poultry organs and tissues harbouring T. canis larvae.

Animal Feed↗

Blastocystis isolates from a pig and a horse are closely related to Blastocystis hominis.

Blastocystis has a widespread distribution in a variety of animals, which is a potential source of infection for humans. However, the contribution of zoonotic transmission remains unclear due to the absence of molecular proof of these organisms being identical to those found in humans. We report herein the similar subgroup of Blastocystis isolates from humans, pigs, and a horse using a restriction fragment length polymorphism (RFLP) analysis of partial small-subunit ribosomal DNA (ssu rDNA). Additionally, sequence and phylogenic analysis of partial ssu rDNA of Blastocystis from a human, a pig, and a horse sharing a common subgroup shows that Blastocystis isolates from a pig and a horse were monophyletic and closely related to B. hominis, with 92 to 94% identity. These results suggest the possibility of zoonotic potential of Blastocystis.

Animals↗

Zoonotic viral diseases and the frontier of early diagnosis, control and prevention.

Public awareness of the human health risks of zoonotic infections has grown in recent years. Currently, concern of H5N1 flu transmission from migratory bird populations has increased with foci of fatal human cases. This comes on the heels of other major zoonotic viral epidemics in the last decade. These include other acute emerging or re-emerging viral diseases such as severe acute respiratory syndrome (SARS), West-Nile virus, Ebola virus, monkeypox, as well as the more inapparent insidious slow viral and prion diseases. Virus infections with zoonotic potential can become serious killers once they are able to establish the necessary adaptations for efficient human-to-human transmission under circumstances sufficient to reach epidemic proportions. The monitoring and early diagnosis of these potential risks are overlapping frontiers of human and veterinary medicine. Here, current viral zoonotics and evolving threats are reviewed.

Animals↗

Serological survey of vector-borne zoonotic pathogens in pet cats and cats from animal shelters and feral colonies.

Although cats and their arthropod parasites can sometimes be important sources of zoonotic diseases in humans, the extent of exposure among various cat populations to many potential zoonotic agents remains incompletely described. In this study, 170 domestic cats living in private homes, feral cat colonies, and animal shelters from California and Wisconsin were evaluated by serology to determine the levels of exposure to a group of zoonotic vector-borne pathogens. Serological positive test results were observed in 17.2% of cats for Rickettsia rickettsii, 14.9% for R akari, 4.9% for R typhi, 11.1% for R felis, and 14.7% for Bartonella henselae. Although vector-borne disease exposure has been documented previously in cats, the evaluation of multiple pathogens and diverse cat populations simultaneously performed here contributes to our understanding of feline exposure to these zoonotic pathogens.

Animals↗

Blastocystis ratti induces contact-independent apoptosis, F-actin rearrangement, and barrier function disruption in IEC-6 cells.

Blastocystis is an enteric protozoan purportedly associated with numerous clinical cases of diarrhea, flatulence, vomiting, and other gastrointestinal symptoms. Despite new knowledge of Blastocystis cell biology, genetic diversity, and epidemiology, its pathogenic potential remains controversial. Numerous clinical and epidemiological studies either implicate or exonerate the parasite as a cause of intestinal disease. Therefore, the aim of this study was to investigate the pathogenic potential of Blastocystis by studying the interactions of Blastocystis ratti WR1, an isolate of zoonotic potential, with a nontransformed rat intestinal epithelial cell line, IEC-6. Here, we report that B. ratti WR1 induces apoptosis in IEC-6 cells in a contact-independent manner. Furthermore, we found that B. ratti WR1 rearranges F-actin distribution, decreases transepithelial resistance, and increases epithelial permeability in IEC-6 cell monolayers. In addition, we found that the effects of B. ratti on transepithelial electrical resistance and epithelial permeability were significantly abrogated by treatment with metronidazole, an antiprotozoal drug. Our results suggest for the first time that Blastocystis-induced apoptosis in host cells and altered epithelial barrier function might play an important role in the pathogenesis of Blastocystis infections and that metronidazole has therapeutic potential in alleviating symptoms associated with Blastocystis.

Actins↗

Prevalence of enteric pathogens in dogs of north-central Colorado.

To evaluate the prevalence of enteric pathogens in dogs of north-central Colorado, fecal samples were obtained from client-owned dogs presented to the Veterinary Teaching Hospital at Colorado State University for evaluation of acute small-bowel, large-bowel, or mixed-bowel diarrhea (n=71) and from age-matched, client-owned, healthy dogs (n=59). Infectious agents potentially associated with gastrointestinal disease were detected in 34 of 130 (26.1%) fecal samples. Agents with zoonotic potential were detected in feces from 21 (16.2%) of 130 dogs and included Giardia spp. (5.4%), Cryptosporidium parvum (3.8%), Toxocara canis (3.1%), Salmonella spp. (2.3%), Ancylostoma caninum (0.8%), and Campylobacter jejuni (0.8%). Positive test results occurred in dogs with or without gastrointestinal signs of disease. Dogs, particularly those in homes of immunocompromised humans, should be evaluated for enteric zoonotic agents.

Ancylostoma↗

Parasitic zoonoses in Papua New Guinea.

Relatively few species of zoonotic parasites have been recorded in humans in Papua New Guinea. A greater number of potentially zoonotic species, mostly nematodes, occur in animals but are yet to be reported from humans. Protozoa is the best represented group of those infecting man, with Giardia duodenalis, Cryptosporidium parvum, Cyclospora cayetanesis, Toxoplasma gondii, Sarcocystis spp., Entamoeba polecki, Balantidium coli and, possibly, Blastocystis hominis. The only zoonotic helminths infecting humans include the trematode Paragonimus westermani, the cestodes Hymenolepis nana, H. diminuta and the sparganum larva of Spirometra erinacea, and the nematodes Trichinella papuae and Angiostrongylus cantonensis and, possibly, Ascaris suum. Other groups represented are Acanthocephala (Macracanthorhynchus hirudinaceus)), insects (Chrysomya bezziana, Cimex sp., Ctenocephalides spp.), and mites (Leptotrombidium spp. and, possibly Sarcoptes scabiei, and Demodex sp.). One leech (Phytobdella lineata) may also be considered as being zoonotic. The paucity of zoonotic parasite species can be attributed to long historical isolation of the island of New Guinea and its people, and the absence until recent times of large placental mammals other than pig and dog. Some zoonotic helminths have entered the country with recent importation of domestic animals, in spite of quarantine regulations, and a few more (two cestodes, one nematode and one tick) are poised to enter from neighbouring countries, given the opportunity. Improvement in water supplies, human hygiene and sanitation would reduce the prevalence of many of these parasites, and thorough cooking of meat would lessen the risk of infection by some others.

Animals↗

Porcine endogenous retrovirus integration sites in the human genome: features in common with those of murine leukemia virus.

Porcine endogenous retroviruses (PERV) are a major concern when porcine tissues and organs are used for xenotransplantation. PERV has been shown to infect human cells in vitro, highlighting a potential zoonotic risk. No pathology is associated with PERV in its natural host, but the pathogenic potential might differ in the case of cross-species transmission and can only be inferred from knowledge of related gammaretroviruses. We therefore investigated the integration features of the PERV DNA in the human genome in vitro in order to further characterize the risk associated with PERV transmission. In this study, we characterized 189 PERV integration site sequences from human HEK-293 cells. Data showed that PERV integration was strongly enhanced at transcriptional start sites and CpG islands and that the frequencies of integration events increased with the expression levels of the genes, except for the genes with the highest levels of expression, which were disfavored for integration. Finally, we extracted genomic sequences directly flanking the integration sites and found an original 8-base statistical palindromic consensus sequence [TG(int)GTACCAGC]. All these results show similarities between PERV and murine leukemia virus integration site selection, suggesting that gammaretroviruses have a common pattern of integration and that the mechanisms of target site selection within a retrovirus genus might be similar.

3' Flanking Region↗

[Zoonoses as a risk when associating with livestock or animal products].

The risk of zoonotic disease transmission when handling livestock or animal products is substantial. In industrialized countries, the classical zoonotic diseases such as tuberculosis or brucellosis are no longer in the foreground. Latent zoonoses such as salmonellosis and campylobacteriosis can cause serious disease in humans and have become a major public health problem during the past years. Since animals infected with these pathogens show only mild transient disease or no clinical signs at all, new concepts in the entire production line ("stable to table") are necessary in order to avoid human infection. Two emerging viruses with zoonotic potential--avian influenza virus and Nipah virus--have been found in Asia in 1997 and 1999. Both diseases had a major impact on disease control and public health in the countries of origin. In order to cope threats from infectious diseases, in particular those of public health relevance, a combined effort among all institutions involved will be necessary. The proposed "European Center for Infectious Diseases" and the "Swiss center for zoonotic diseases" could be a potential approach in order to achieve this goal.

Animal Husbandry↗

Zoonotic diseases of cats.

As veterinarians, our responsibilities do not end with the care of our patients. The welfare of our clients and their families depends on our ability to detect and control potentially zoonotic diseases in their pets. Because some of these zoonoses can have devastating effects on the development of the unborn fetus or on family health in general, discussion about these diseases between veterinarian and client is often emotionally charged. Under such circumstances, the offering of inaccurate and erroneous information by the veterinarian can have drastic consequences. It is likely that other zoonotic diseases of domestic pets will be identified in the future, especially those that can cause opportunistic infections in debilitated and immunodeficient persons. In the meantime, the potential hazards of cat ownership can be significantly reduced through an increased understanding of feline diseases and an improved level of health care for our feline patients.

Adolescent↗

Hedgehog zoonoses.

Exotic pets, including hedgehogs, have become popular in recent years among pet owners, especially in North America. Such animals can carry and introduce zoonotic agents, a fact well illustrated by the recent outbreak of monkeypox in pet prairie dogs. We reviewed known and potential zoonotic diseases that could be carried and transmitted by pet hedgehogs or by wild-caught hedgehogs that have been rescued.

Animals↗

A retrospective study of the clinical hematology and the serum biochemistry tests made on canine dirofilariasis cases in an animal hospital population in Bangkok, Thailand.

Heartworm disease, caused by the filarial nematode, Dirofilaria immitis, is a major, potentially life-threatening disease of dogs, with worldwide distribution and global significance. It is not only of veterinary importance but it also has zoonotic potential in many regions. It is considered as an endemic disease in Thailand, although clinical data about the disease is rarely reported. The objectives of this study were to characterize the clinical hematology and the biochemistry of canine dirofilariasis cases admitted to Chulalongkorn University, Small Animal Teaching Hospital in Bangkok, Thailand, from 2001-2003. All hematology and serum biochemistry parameter interpretations were based on reference values. A total of 1023 dogs were evaluated in this study. Dogs were divided into three groups based on their heartworm classification (microfilaremic, occult and negative). The major hematological findings in microfilaremic dogs were a mild to moderate anemia, mild to severe thrombocytopenia, marked leukocytosis, moderate to marked neutrophilia, eosinophilia and monocytosis. The most common serum biochemical abnormalities in microfilaremic dogs included increased alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase with a mean+/-SD of 311+/-299, 82+/-76 and 50+/-38 IU/L, respectively. It is likely that this parasitic infection led to the impairment of the hematological and biochemical status of the infected dogs. We believe that investigation of these laboratory based parameters, when associated with the clinical signs, is a very important approach to be considered in the routine clinical follow up, as well as being important for therapeutic evaluations.

Animals↗

Anaplasma phagocytophilum in ruminants in Europe.

The agent that causes tick-borne fever (TBF) in sheep was first described in 1940, 8 years after the disease was first recognized in Scotland. The same agent was soon shown to cause TBF in sheep and pasture fever in cattle in other parts of the UK, Scandinavia, and other parts of Europe. After the initial use of the name Rickettsia phagocytophila, the organism was given the name Cytoecetes phagocytophila to reflect its association with granulocytes and its morphological similarity with Cytoecetes microti. This name continued to be used by workers in the UK until the recent reclassification of the granulocytic ehrlichiae affecting ruminants, horses, and humans as variants of the same species, Anaplasma phagocytophilum. TBF and pasture fever are characterized by high fever, recurrent bacteremia, neutropenia, lymphocytopenia, thrombocytopenia, and general immunosuppression, resulting in more severe secondary infections such as tick pyemia, pneumonic pasteurellosis, listeriosis, and enterotoxemia. During the peak period of bacteremia as many as 90% of granulocytes may be infected. The agent is transmitted transtadially by the hard tick Ixodes ricinus, and possibly other ticks. After patent bacteremia, sheep, goats, and cattle become persistently infected "carriers," perhaps playing an important role in the maintenance of infection, in the flock/herd. Little is known about how efficiently ticks acquire and maintain infection in ruminant populations or whether "carrier" domestic ruminants play an important role as reservoirs of infection, but deer, other free-living ruminants, and wild rodents are also potential sources of infection. During the late 1990s serological evidence of infection of humans was demonstrated in several European countries, creating a renewed interest and increased awareness of the zoonotic potential of TBF variants. More recently, a few cases of human granulocytic anaplasmosis (HGA) have been reported in some European countries, but it remains to be established whether the variants causing HGA in Europe are genetically and biologically different from those causing TBF in ruminants. TBF is readily diagnosed by demonstrating intracytoplasmic inclusions in peripheral blood granulocytes or monocytes of febrile animals or by detecting specific DNA by polymerase chain reaction (PCR), and TBF variants of A. phagocytophilum can be cultivated in tick cell lines, but the differentiation of TBF variants from HGA variants awaits further investigations.

Anaplasma phagocytophilum↗

Biological warfare training. Infectious disease outbreak differentiation criteria.

The threat of biological terrorism and warfare may increase as the availability of weaponizable agents increase, the relative production costs of these agents decrease, and, most importantly, there exist terrorist groups willing to use them. Therefore, an important consideration during the current emphasis of heightened surveillance for emerging infectious diseases is the capability to differentiate between natural and intentional outbreaks. Certain attributes of a disease outbreak, while perhaps not pathognomic for a biological attack when considered singly, may in combination with other attributes provide convincing evidence for intentional causation. These potentially differentiating criteria include proportion of combatants at risk, temporal patterns of illness onset, number of cases, clinical presentation, strain/variant, economic impact, geographic location, morbidity/mortality, antimicrobial resistance patterns, seasonal distribution, zoonotic potential, residual infectivity/toxicity, prevention/therapeutic potential, route of exposure, weather/climate conditions, incubation period, and concurrence with belligerent activities of potential adversaries.

Biological Warfare↗

Biological warfare training: infectious disease outbreak differentiation criteria.

The threat of biological terrorism and warfare may increase as the availability of weaponizable agents increases, the relative production costs of these agents decrease, and, most importantly, there exist terrorist groups willing to use them. Therefore, an important consideration during the current period of heightened surveillance for emerging infectious diseases is the ability to differentiate between natural and intentional outbreaks. Certain attributes of a disease outbreak, although perhaps not pathognomonic for a biological attack when considered singly, may combine to provide convincing evidence of intentional causation. These potentially differentiating criteria include proportion of combatants at risk, temporal patterns of illness onset, number of cases, clinical presentation, strain/variant, economic impact, geographic location, morbidity/mortality, antimicrobial resistance patterns, seasonal distribution, zoonotic potential, residual infectivity/toxicity, prevention/therapeutic potential, route of exposure, weather/climate conditions, incubation period, and concurrence with belligerent activities of potential adversaries.

Biological Warfare↗

Prevalence and infection risks of zoonotic enteropathogenic bacteria in Swiss cow-calf farms.

A longitudinal study was performed in 67 larger Swiss cow-calf farms from September 1996 through November 1997. The objectives of the study were to estimate prevalence and risk factors for colonization with potentially zoonotic enteropathogenic bacteria in younger calves and in calves at weaning age. The study included data from 395 calves with three to four fecal samples each. Fecal samples were analyzed for Campylobacter spp., verotoxin producing E. coli (VTEC), Yersinia spp. and Salmonella sp. Possible environmental and individual factors associated with colonization of these agents were examined. The calves were housed indoor during the first 3 months of life (winter 1996/1997). The prevalences within this time period were: C. coli 3.4%, C. fetus 15.5%, C. hyointestinalis 9.6%, C. jejuni 38.5%, VTEC 44.3% and Yersinia spp. 2%. At the end of the grazing season the prevalences at weaning (8-10 months of age) were: C. coli 1.7%, C. fetus 4.0%, C. hyointestinalis 25.9%, C. jejuni 13.3%, VTEC 38.2% and Yersinia spp. 0%. No salmonellae were present at any time of the study. The prevalences of C. jejuni and VTEC increased significantly within the first 3 months of life, whereas C. hyointestinalis decreased. None of the environmental factors such as housing or feeding had any consistent influences on colonization by the bacteria studied. VTEC, Campylobacter spp. and Yersinia spp. should probably be considered as normal inhabitants of the bovine intestinal tract. However, as they represent a source of gastrointestinal infections in humans, management factors limiting intestinal colonization of these bacteria should be considered in cow-calf operations.

Agglutination Tests↗