Zhou Zilian : Professor Zhang Deli lectured on the 3rd-4th lecture on the 3rd and after-class thinking questions in veterinary virology
——1805 Zhou Zilian 2018011024
Thought Questions:
1. What are abnormal (too strong) natural immune response major respiratory viral diseases? What is an inflammatory storm or cytokine storm?
Porcine infectious gastroenteritis virus, porcine reproductive and respiratory syndrome. The inflammatory storm is an overreaction of cytokines, mainly an overreaction of the human immune system to external viruses and infections, and an overreaction of some drugs. When overreacting to the enemy and the enemy, it causes damage to the body itself
2. The importance of the three defenses (anti-nuclear weapons, anti-chemical weapons, anti-biological weapons) is self-evident! At present, biological weapons warfare agents are mainly viruses, why? How harmful is the threat of the use of virus weapons, and what is the use strategy and tactics? Nuclear weapons have used atomic bombs, tested hydrogen bombs, as well as possible neutron bombs and cobalt bombs that are prohibited from research and development, the latter two threats, greater harm, in general, into the war, what are the consequences?
The virus is highly contagious, the fatality rate is high, the harm to the human body is large, and it is not easy to treat. The use strategy is to ensure their own safety. The harm caused by nuclear weapons is a local hazard, while viral weapons are contagious and spread more widely with the flow of people or the air.
After-class thinking questions:
1. Describe the main characteristics and classification of micrornaviridae.
The family has more than 230 members, second only to the Bunia Viridae. There are many important viruses, such as the foot-and-mouth disease virus discovered by lasllfrosch in 188, which is one of the most deeply studied animal viruses in humans, and the structure of the virus has been determined at the atomic level by X-ray linear crystallization imaging.
Classification: ictv In the 8th classification report, there are 9 genera in the family: foot-and-mouth disease virus, enterovirus, cardivirus, rhinovirus, liver virus, paraintestinal virus, equine rhinovirus, crest virus and Jieshen virus. The 9th classification report eliminated the rhinovirus genus and added 12 new genera, including monkey avian porcine enterovirus, Seneca virus, tremor virus and avian hepatitis virus. The previously unidentified avian encephalomyelitis virus and the duck hepatitis virus are now classified as human tremor virus and avian hepatitis virus, respectively. Human rhinovirus A and bovine rhinovirus, which were originally classified in the genus Rhinovirus, are now reclassified to the genus Enterovirus and Foot-and-Mouth Disease virus. Genera are based primarily on differences in genomic layout.
2. What are the serotypes of foot-and-mouth disease virus? Explain why it is susceptible to antigenic drift.
Foot-and-mouth disease virus has seven serotypes, namely o, a, c, sat1, say2, sat3, and Asian type 1, each of which can be further divided into subtypes. Antigenic drift, mainly due to a series of point mutations encoding hemagglutinin (ha) or neuraminidase (na) protein genes, leads to the replacement of antigenic amino acids on the h or n protein molecules associated with point mutations in the ha and na genes in the same subtype, which is quantitative and can cause small and medium-sized epidemics.
3. Elaborate on the epidemic and pathogenic characteristics and countermeasures of foot-and-mouth disease virus.
Pathogenesis: The appearance of water in the mouth, nose, hoof and other parts of the sick animal is the main symptom, and it may be limp. The symptoms vary slightly from animal to animal. Pregnant cows may miscarry, which then leads to reduced fertility. Pigs have sour hooves as the main symptom. Symptoms in goats and sheep are usually milder than those of cattle. Foot-and-mouth disease spreads rapidly and is often widespread in cattle and pigs. In addition to horses, sheep and many kinds of even-hoofed animals are susceptible. The fatality rate of the disease is low, but the infection rate is high. Occasional human infections, mostly in close contact with livestock or laboratory workers, are mostly subclinical infections and may manifest as fever, poor appetite, and blisters in the mouth, hands, and feet. The main route of infection in ruminants is through human suction, but can also be achieved through feeding or exposure to contaminants. When the virus is infected through the respiratory tract, it initially replicates in the pharynx and then spreads to other tissues. In the 24 hours before the onset of clinical disease, the affected animal excretes the virus, and the milk also carries a large amount of the virus for several days. Infected pigs spew out droplets contain a large amount of virus.
The virus can be transmitted over long distances by aerosols and depends on wind direction and speed, especially in low temperatures and high humidity, in dark weather. The 1967-1968 epidemic in the United Kingdom was caused by long-distance aerosol transmission. In 1981, a computer simulated the possibility of a virus crossing the English Channel from France to the United Kingdom. The virus can persist in the pharynx of some recovered animals, up to 2 years in cattle and up to 6 months in sheep. No persistent infection of the virus was found in pigs. Wild animals such as the African buffalo even carry more than one subtype of sat. The mechanism by which the virus produces persistent infection in anti-animals remains unclear. Rehabilitation is associated with the production of antibodies. Early igm antibodies can neutralize both homoviruses and anti-heterotypical viruses. LGG produced during convalescent period is type-specific or subtype-specific. The immunity of recovered cattle to homoviral infections can be maintained for 1 year or slightly longer. The role of cellular immunity, like other micrornavirus infections, is generally considered to be of little significance.
4. How to distinguish between foot-and-mouth disease virus wild virus infection and vaccination?
Diagnosis of foot-and-mouth disease can only be carried out in designated laboratories. Samples sent for testing include vesicle fluid, flaking vesicle skin, anticoagulant blood, or serum. Dead animals can also collect lymph nodes, tonsils and hearts. Samples should be frozen or placed in glycerol buffer at ph7.6. There are several detection methods. OIE recommends using commercialized and standardized elisa kits, where results can be obtained within hours if the vesicular fluid or tissue contains a sufficient amount of antigen. RT PCR can be used to detect viruses in samples. If the titer of the virus in the sample is low, the virus can be isolated using bhk-21 cell culture. Isolated viruses are identified by elisa or neutralization tests. It used to be thought that wild virus infections could be distinguished from vaccination by antibodies that detect via (virus-associated antigens). Now known, via is actually a viral polymerase (3D protein), which is also found in vaccines, and detecting 3D antibodies does not distinguish infection from immunity. Instead, 3abc antibodies, which are non-structural proteins not found in vaccines, are negative for 3abc antibodies in immune animals and positive for infected animals.
5. Compare the similarities and differences between porcine vesicle virus and foot-and-mouth disease virus.
Porcine vesicular virus has a similar incidence to foot-and-mouth disease virus, with fever, crested blisters, and occasionally encephalomyelitis. Can be identified by elisa and RT-PCR.
6. What are the pathogenic characteristics of enteroviruses in pigs and poultry?
On pigs, it is manifested as fever, blisters in the crown of the hooves, etc., and has a strong effect. Encephalomyelitis is often caused in poultry, but it is mild.
7. What is the reservoir owner and pathogenesis of cerebrocarditis virus?
The natural host of this virus is water rats and other dentists, which are transmitted to humans, monkeys, horses, cattle, pigs and elephants through odontists. Myocardial tubes in herds and elephant herds in the United States, Australia and South Africa have caused death. It has also been found that the virus is associated with nonpurulent meningoencephalitis in dogs and cats. Epicv antibodies can be detected in special populations such as hunters, suggesting that the virus may have public health significance. The virus is invaded by oral humans. Epithelial cells in the digestive tract replicate. Viremia can occur within 1 day of artificial infection of pregnant sows, and the virus can be detected in the stock class for at least 8 days. Piglet infection for 2d can isolate the virus in any tissue. Histological examination may show cardiomyocytes and Purkinye fibrointerstitial myocarditis and necrosis, as well as necrotizing shoulderillitis and interstitial pancreatitis. EMCV has a high lethality rate for littering and causes sow reproductive disorders. Emcv has only one serotype, but the pathogenicity of the strains is different, which may be related to the poly (c) length in the viral genome and the amino acid sequence of the vpi protein. It can agglute the red application of guinea pigs, mice, etc. Can proliferate in the chicken area, and then can be adapted to vero or bhc21 cells, and produce cpe. Diagnosis can be isolated virus, with rt-pcr detection of viral nuclear risk in the disease Xuan, neutralization test and elisa detectable antibodies, removal of contaminated rodents and rodent extermination is an effective measure of prevention and control, prevention can be inoculated inactivated inflamed, has shown a protective effect in elephant herds.
1. What are the structural characteristics of the inggregulated virus?
The main characteristics of the virus particles are non-cystic membrane, diameter 40 nm, nucleocapsid 20 patahedral symmetry. The viral capsid consists of 90 identical arched catamarin subunits, resulting in 32 cup-like depressions on the surface (Figure 36-1), hence the virus's characteristic cup-cup structure. Some strains of the genus Novavirus are hairy, spherical, and were once called microsphere viruses.
2. Describe the pathogenic characteristics and differential diagnosis of cat cup virus.
Pathogenesis: Spread by aerosol and contact, cat traders are more important vectors. The incubation period is 2 to 6 days. A considerable number of recovered cats excrete the virus from the oropharynx, which can last for years or even life. Cats present with conjunctivitis, rhinitis, tracheitis, pneumonia, and mouth ulcers. Cats over 1 year of age rarely develop the disease due to the production of antibodies. The incidence of kittens is high, and the mortality rate of cats can reach 30%.
Diagnosis: symptoms alone cannot be distinguished from feline herpes virus type 1 infection, and electron microscopy can be used to differentiate. Or isolate the virus with feline-derived cells, and then do fluorescent antibody staining or elisa to confirm the diagnosis.
3. Describe the transmission route, pathogenic characteristics, diagnosis and prevention and control of rabbit hemorrhagic virus
Pathogenic mechanism: The virus is transmitted through the fecal oral route, and it is free from susceptibility at least 2 months of age. The most acute patients usually die within 6 to 24 years. Nasal fluid may be seen in acute or subacute cases and may present with various neurological symptoms, with an incidence of 100%, a mortality rate of 90%, and a coagulant clot filling the blood vessels of the tissues of the whole body: intravascular coagulation may cause hepatic necrosis. The virus can agglute human red blood cells, which are affected by physical glycolipids. Australia and New Zealand introduced rhdv to control too many local wild households, and unexpectedly, mosquitoes, flies and carnivorous birds such as crows and eagles can be used as vectors for the transmission of the virus.
Diagnosis: from the infected tissue mainly the liver can obtain a high titer of the virus, with human red blood cells to do hemagglutination test, and then with antibodies to do blood coagulation inhibition test can confirm the diagnosis. Diagnosis can also be made by other methods such as electron microscopy (Figure 36-3) or elisa.
Prevention and control: Rabbit hemorrhage is a notifiable disease prescribed by OIE. In addition to strict isolation and disinfection measures, liver and other homogeneous slurries can be taken to make inactivated vaccines, immunization of the free group, the toxic vp60 gene can be expressed with baculovirus, and produce nucleic acid-free virus-like particles, which are effective for oral or injectable immunization, but not commercialized.
4. What are the characteristics of hepatitis E virus?
It has similarities with the phiviridae, its replication enzymes have high homology with the wind master virus, etc. Have high homology, the nature of its additive enzyme (apping enyme) and the 8th classification report of the alphavirus ictv did not determine its family, the international conference on viral liver immunity held in 200 was determined to be a good degree of need, and translated as the formed hepatitis virus family, and the 9th virus classification report of iCTV in 202 was confirmed.
There is only one genus in the family Hepatitis E: tiger liver virus. Hepatitis E virus is currently the only member of the genus. The genome is a positive-chain RNA, about 7 200nt in size, divided into 3 reading frames, orfi encodes non-structural proteins, orf2 encodes the main capsid protein (cp), orf3 overlaps orf1 and orf2, and small molecule phosphoproteins encoding 113-114 amino acids are unknown. CP molecular mass 720 hev can be divided into 5 genotypes, types 1 and 2 only infect humans, types 3 and 4 infect humans and animals, types 1-4 have cross-immunity, and the agglomerate strains of hev belong to genotypes 3 and 4.
5. What are the pathogenic characteristics of astroviruses? How is it detected?
The main characteristics of the virus particles are obviously fibrous, diameter 28 ~ 30 nm, 20 phenakonal symmetry. After negative infection, electron microscopy observes that about 10% of patients have a five-pointed or hexagonal star shape, hence the name. The genome is a single molecule linear positive-chain RNA with a size of 6 800 nt. The 5' terminal is covalently bound to vpg protein, and the 3' terminal is polya-a-tail. RNA is infectious. The molecular masses of the two main capsid proteins are 90,000u and 27,000 to 30,000u, respectively. The virus produces full-length genomic RNA and 24,000nt subgenomic RNA during replication, which encodes the precursor to the main capsid protein. The virus replicates in the cytoplasm, and mature viral particles accumulate in a lattice-like arrangement within the cytoplasm and are released by cell lysis. Bovine, pig, cat and human astrovirus can grow in homologous primary embryonic kidney cells, and pigs and human astrovirus can also be adapted to passage cell line culture, but 10 ug ml of trypsin is added to activate the binding of the virus to the cell. This virus is resistant to ph3, 50c after 1h, 60c for 5min, lipid solvents and detergents. RT-pcr detects this virus.
6. What is the classification of the philaviridae and its importance to veterinary medicine?
The taxonomy is divided into alphavirus and rubella virus. The latter is only a species, for the rubella virus that infects humans. There are 29 members of the genus Alphavirus, 6 of which mainly cause disease in horses and are pathogenic to humans, with obvious geographical distribution characteristics. The representative species is Sindbis virus, transmitted to humans by Anopheles mosquitoes, and the virulence of the strains is different, most of which cause asymptomatic infection, and a few cause polyarthritis, rash and fever.
7. How is the flaviviridae classified? What are the characteristics of each?
There are three genera in the taxonomy: flavivirus (fatirm), phytovirus cpeanerna and hepatitis C virus hpurtin (Table 6-3). There are more than 69 species of flavivirus species, most of which are human-seeing comendiophiles, which can be divided into three major complex groups according to the similarity of their collective cause groups and the distribution of neutral epitopes: mosquito-borne complex group, fresh coal complex group and unknown tijie group. Some members have not been able to group. The vast majority of life history includes the circulation of insects and vertebrates, the Japanese encephalitis virus and West Nile virus in mosquito-borne complex groups are relatively important zoonotic pathogens, and the duck tambusu virus is a newly discovered waterfowl pathogenic virus in China.
Plague viruses include swine fever virus, bovine viral diarrhea virus type 1 (bvdv1) and type 2 (bvdv2), and border area disease virus, which are important medical research objects. Genetic sequencing showed that they were closely related, and although natural infections were distinctly host-specific, experimental infection with swine fever viruses could infect cattle, and bvdv could infect pigs, sheep, and other ruminants.
8. What is the relationship between the main members of the plague genus?
Didn't look for it
9. What are the biological types of bovine viral diarrhea virus? What are the differences in pathogenicity and genetic structure?
The differentiation of species is based on differences in pathogenicity, antigenicity and gene sequence, heinz et al. (0000 proposed to divide bvdv into two species: bvdv1 and bvdv2. Both can cause bovine viral diarrhea and mucosal disease, but bvdv2 is more virulent and can also cause acute onset in adult cattle, resulting in severe thrombocytopenia and hemorrhagic syndrome, which has similar pathogenic characteristics to swine fever virus. However, bvdv2 does not cross the antigenicity of swine fever virus, and bvdv1 has. The latter can also infect pigs naturally. The sequence difference of 5 non-coding regions (ncr) of the genomes of members of the plague virus genus > 15%, as does bvdv1 versus bvdv2.
10. Describe the transmission characteristics and detection methods of swine fever virus.
The typical swine fever is an acute infection with high fever, anorexia, conjunctivitis. Incubation period 2 to 4d. The leukocytes of sick pigs are severely reduced, lower than the level of any other swine disease. Piglets can die asymptomatic. The adult died within 1 week due to the feeling of thin face. The mortality rate can be as high as 100%. The incubation period and course of the subacute and chronic types are prolonged, and the viral virulence is weakened. Infection of huaihua sows by this strain leads to stillbirth, miscarriage, mummy fetus or stillbirth, and the piglets produced by the undead develop immune tolerance, manifested by trembling, shortness and lifelong detoxification, mostly within months of death. Sick pigs or asymptomatic persistently infected domestic pigs (mainly breeding pigs) and wild boars are sources of direct contact. In addition, various utensils such as vehicles, shoes of pig farm personnel, etc. can also be transmitted indirectly.
Diagnosis: it should be performed in a nationally recognized laboratory. The material may be pancreas, lymph nodes, tonsils, spleen and blood. Viral antigens in tissues can be rapidly detected by fluorescent antibody staining, immunohistochemistry, or antigen capture elisa, and swine fever virus nucleic acids in samples can also be detected using rt-pcr. Viruses can be isolated by cell culture, but because no CPE is produced, further detection of the virus is required by immunological methods.
11. What are the characteristics and pathogenic significance of the trevally nerve necrosis virus?
This virus is a representative species of the genus Nodamura virus type B. The virus particles are capsule-free, spherical, symmetrical in 20-sided, with an average diameter of 37 mm, and the surface of the virus particles can be seen under sample electron microscopy with obvious protrusions. The genome is a single positive strand of rna of two molecules, and the two are together to have a sense neutrality. RNAI is 3 100nt. RNA2 is 1400 nt, and neither has a polyax tail at the 3' end. There are also 400mt of subgenic rna3 in infected cells derived from rnai, which is not assembled into viral particles and has unknown function. The nucleocapsid protein has a molecular mass of 42,000 u, encoded by rna2, and RNAi encodes a molecular mass of 110,000 u of RNA polymerase. The virus can tolerate chloroform, 56c through 30min and ph2 to 9. In addition to sjnnv, the confirmed members of this genus include flounder nerve necrosis virus, grouper neuronal necrosis virus, and thirone nerve necrosis virus. The above viruses have antigenic crosses with sjnnv, and the main infected objects are sea bass, grouper, yellow-banded koji, flounder, turbot, turbot, catfish, etc., involving at least 11 families and 22 species of fish, which are found in marine fish nurseries almost all over the world except in the Americas and Africa. Fry are the most susceptible, characterized by vacuolarized encephalopathy and retinopathy. Symptoms are predominantly neurological behavioral abnormalities, with high mortality rates, some up to 100%. Tissue sections of diseased fish show nerve cell necrosis and intracytoplasmic inclusion bodies.
12. What are the pathogens and characteristics of white-tailed disease?
The main characteristics of viral particles are free of cystic membranes. Spherical, 20-sided symmetrical, diameter 26 to 27 nm. Pentagon or hexagonal. It is the main pathogen of Giant River Prawn whitetail disease (also known as Roche shrimp muscle white turbidity disease, wmd). In addition, it was found that the satellite virus of the virus, called the ultra-small virus, is similar in morphology to mrnv, but smaller, with a diameter of 14 to 16 nm, and the pathogenicity of xsv is unknown. Mrnv xsv is easy to culture in the Aedes albopictus c6/36 cell line at a culture temperature of 28c.
Pathogenesis: Infected Giant River P. rosenbergii larvae and juvenile shrimp died on a large scale, and adult shrimp were resistant but could be used as carriers of poison. The virus can be transmitted vertically through broodstock to juvenile shrimp. It may be transmitted in shrimp fry breeding grounds by both horizontal and vertical transmission. Shrimp (Penaeus indica, Penaeus monodon, Nippon shrimp), brine worms, large insects, silkworms, dragon lice, pine algae worms, etc. can be used as vectors for the transmission of white tail disease