Infection Disease Prevention and Treatment of Bird Flu Avian influenza virus
Meaning of Bird Flu: Avian influenza virus (AIV) is an
influenza A virus. Influenza viruses belong to the Orthomyxoviridae family of
RNA viruses, which are divided into three types: A, B and C. Influenza A
viruses are more common in poultry, and some A can also infect various mammals
and humans such as pigs, horses, seals and whales. Influenza B and C viruses
are found in seals and pigs, respectively.
It is the viral influenza of poultry, which is an infectious
disease caused by influenza A virus, which is a variety of symptoms of poultry
ranging from respiratory system to severe systemic sepsis. Avian influenza is
easy to spread among birds. In the past, it was called "chicken
plague" by the people. It was classified as a Class A infectious
disease by the International Bureau of Veterinary Disease.
Avian influenza
outbreaks occurred in Australia, Italy, Hong Kong, and the Netherlands in 1994,
1997, 1999 and 2003, respectively, and mainly in Southeast Asia and Europe in
2005.
Medical Name: Bird
flu virus
English name: AIV
Onset: Respiratory
tract
Multiple groups:
Children, the elderly
Infectious: Yes
Way for spreading:
Breath
What is the Prevention of Bird Flu Virus AIV?
Avian influenza generally occurs in spring and winter, and it
is generally not transmitted from person to person. Pay attention to the following
points to prevent avian induction:
a. Wash your hands
frequently. Be away from the secretions of poultry, contact with poultry, birds or
poultry and bird droppings. Please wash your hands thoroughly with
disinfectant and water to avoid traveling to the infected area.
b. Develop good
personal hygiene habits. Cover your mouth with your hands or toilet paper when
coughing. Strengthen indoor air circulation. Open the window 1 to 2 times a day
for half an hour. Have enough sleep and rest. Eat a balanced diet. Pay
attention to taking more photos Into some foods rich in vitamin C and other
immune-enhancing food.
c. Eat poultry meat to be cooked and cooked through. When
eating eggs, the eggshells are washed with running water first, and the cooking
is fully heated. Do not eat raw or half-cooked eggs.
What is Bird Flu Virus Morphology?
Polymorphism, in which the spherical diameter is 80 - 120nm,
there is capsule. The genome is segmented single stranded negative strand RNA.
According to the difference in the antigenicity of the outer membrane
hemagglutinin (H) / and neuraminidase (N) proteins, it can be divided into 16 H
subtypes (H1 - H16) and 9 N subtypes (N1 - N9).
The subtypes of avian influenza
viruses infecting humans are mainly H5N1, H9N2, and H7N7. Among them, patients
infected with H5N1 are severely ill and have a high mortality rate.
Studies performed
Studies have shown that the original low-pathogenic avian
influenza virus strains (H5N2, H7N7, H9N2) can become highly pathogenic virus
strains (H5N1) after rapid mutations among the birds of 6-9 months.
Epidemiology
Avian influenza virus attacks healthy cells
Breed in the digestive tract of waterfowl.
They are mainly poultry infected with avian influenza or
carrying avian influenza virus. In addition, wild birds or pigs can also be the
source of infection.
Many poultry can be infected with the virus:
Turkey,
chicken, pigeon, guinea fowl, quail, parrot and other land birds can be infected,
but turkey and chicken are the most susceptible, with high morbidity and
mortality.
Ducks and Waterfowls such as geese are also susceptible to
infection, and can carry poison or recessive infections, and sometimes die in
large numbers. Chickens and turkeys of various ages can be infected and die,
while the mortality rate for waterfowls such as ducklings and goslings is high.
In addition to wild birds, such as swans, terns, wild ducks,
coastal birds and seabirds, influenza viruses have been isolated from the
following species of birds.
Starlings, rock chickens, sparrows, crows,
jackdaws, pigeons, rock partridges, Swallows, herons, Canada geese and muscovy
ducks.
According to reports, 88 species of birds with avian influenza
virus have been found, and rodents cannot be naturally infected with influenza
virus.
Different breeds of poultry have different chances of being
infected with avian influenza, but it has not been found that the occurrence of
highly pathogenic avian influenza is related to the gender of the bird. The
highly pathogenic avian influenza virus can also be transmitted through eggs.
The transmission of highly pathogenic avian currents between
flocks mainly depends on horizontal transmission, such as air, feces, feed and
drinking water.
There is little evidence of vertical transmission. However,
experiments have shown that the eggs infected with chickens contain influenza
virus, so the possibility of vertical transmission cannot be completely ruled
out. Therefore, eggs from contaminated chickens should not be used for
hatching.
The virus can be excreted with the respiratory tract, eye and
nose secretions, and feces of sick birds, and the birds are infected through
the digestive tract and respiratory tract.
Any object contaminated with sick
poultry feces and secretions, such as feed, poultry houses, cages, feeding and
management equipment, drinking water, air, transportation vehicles, people,
insects, etc., may spread the virus.
What is the Way for Spreading of Bird Flu Virus?
Mainly through the respiratory tract, through close contact
with infected birds and their secretions, excreta, virus-contaminated water,
etc., and direct contact with virus strains are infected.
The feces infected
with waterfowl contain a high concentration of virus and spread the influenza virus
through the fecal-oral route through the contaminated water source.
No
concealed carriers of human infection have been found, and there is no definite
evidence of human-to-human transmission.
Susceptible crowd
It is generally believed that there is susceptibility at any
age, but children under 12 years old have a higher incidence and a serious
condition. High-risk groups are those who have close contact with poultry that
has died of unknown causes or infected poultry that is suspected of being
infected with avian influenza.
What are the Popular Features of Bird Flu Virus?
Avian influenza is distributed worldwide, with outbreaks in
1994, 1997, 1999, and 2003 in Australia, Italy, Hong Kong, and the Netherlands,
respectively. In 2005, outbreaks occurred mainly in Southeast Asia and Europe.
Except for the bird flu in chickens, which occurs mainly in winter and spring,
there are no other obvious regularities.
The spread of the highly pathogenic
avian influenza epidemic has attracted worldwide attention.
The analysis of the
climate characteristics of the epidemic area by Chinese meteorologists shows
that avian flu "dislikes" sunny and hot weather.
The World Health Organization (WHO) believes that sick
poultry manure is the main transmission channel, and some experts believe that
migratory bird migration is also one of the transmission channels.
Weather and climate conditions are an important factor in the
natural environment, and their changes or abnormalities usually play a role in
the occurrence, aggravation or alleviation of some diseases.
Experts believe
that the avian influenza virus likes to be cold and humid, and the ultraviolet
rays in the sun have a certain killing effect on the virus.
In the late winter
and early spring, cold air activity is frequent, and the temperature rises and
falls suddenly, which will be detrimental to the control and prevention of the
occurrence of bird flu.
In addition, as the temperature warms up, migratory
birds will migrate northward, and the range of viruses transmitted by migratory
birds will expand, which will also be detrimental to the control of bird flu.
The WHO believes that the H5N1 avian influenza virus strain
in sick chicken faeces will spread in the air and be carried away by the wind
to spread avian influenza.
Judging from the hours of sunshine, the analysis
shows that areas with less sunshine are prone to bird flu. This is consistent
with the opinion put forward by agricultural experts that the avian influenza
virus can only survive for 24 to 28 hours in the sun, and is generally
prevalent in the winter and spring seasons, and basically calms down from May
to October.
The highly pathogenic avian influenza virus is mainly
transmitted through the air. With the help of hemagglutinin (H) on the surface
of the virus, it binds to the corresponding receptor on the surface of the
respiratory mucosal epithelial cells and adsorbs it on the host respiratory
epithelial cells.
In addition, by using the neuraminidase (N) on the surface of
the virus to act on the receptor of the nuclear protein, the virus and the nuclear
protein of the epithelial cell are combined to form an RNA-type soluble antigen
in the nucleus, and it leaks to the cytoplasm and replicates the progeny.
The
virus, through the action of neuraminic acid, expels the epithelial cells in a
budding manner. The cycle of a replication process is 4 to 6 hours.
The
discharged virus spreads to nearby cells and produces an inflammatory response.
Clinically, fever, muscle pain and leukopenia and other systemic toxicemia-like
reactions occur.
The virus mainly invades the epithelial cells of the
respiratory tract mucosa, causing epithelial cell hyperplasia, necrosis, local
mucosal hyperemia, edema, and superficial ulcers.
After 4-5 days, the basal
cell layer lesions can expand to the bronchi, bronchiole, alveoli and bronchial
tissues, causing mucosal edema, hyperemia, lymphocyte infiltration, and
accompanied by microvascular embolism, necrosis, small aneurysm formation and
bleeding, etc. Systemic toxemia-like reaction.
In addition to changes in
bronchiolitis, a small number of severe progressive pneumonia may have alveolar
wall congestion and edema, fibrin exudation, mononuclear cell infiltration and
hyaline membrane formation, and pulmonary hemorrhage, etc., causing many
complications.
The highly pathogenic avian influenza virus is highly
virulent, and the infectious allergic reaction (type IV allergy) caused by
severe pneumonia, acute respiratory distress syndrome (ARDS) and multiple organ
dysfunction syndrome (MODS) is serious. The root cause of complications.
What is the Relationship of Bird Flu Virus with Humans?
Human research and prevention of bird flu have a history of
more than 100 years. Gene fragments, unless avian influenza viruses and human
influenza viruses undergo genetic recombination, it is difficult to invade
humans and cause transmission from person to person.
The occurrence of human
bird flu can only be caused by contact with sick birds. People have a low
chance of contracting the virus.
Avian influenza viruses are influenza A viruses. Influenza
viruses belong to the Orthomyxoviridae family of RNA viruses, which are divided
into three types A, B and C.
What are the Pathological changes under Bird Flu?
Simple flu?
Only the catarrhal inflammation of the upper respiratory
tract changed, and the mucosa showed hyperemia, edema and lymphocyte
infiltration. Fibroepithelial cells are degenerated, necrotic and shed.
Pneumonia influenza
The lungs are dark red edema. There are bloody secretions and
mucosal congestion in the trachea and bronchi.
The ciliated epithelial cells
are necrotic and shed. There is submucosal focal hemorrhage, edema and leukocyte
infiltration.
There is fibrin exudate in the alveoli, including neutrophils and
lymphocytes. There is bleeding in the alveoli of the middle lobe of the lung,
and there may be a transparent membrane in the alveoli, and the lung tissue is
easy to isolate influenza virus.
What are the Serious Complications under Bird flu?
The main pathological change is lung consolidation. Pulmonary
interstitial edema and reduced interstitial negative pressure increase the
tendency of small airway occlusion, resulting in atelectasis. There is reduced alveolar
membrane surfactant and alveolar occlusion.
Combined with congestion of the
lungs, lung volume decreases and lung compliance Sexual decline, leading to
serious complications such as acute respiratory syndrome.
There are differences in receptor specificity, and the avian
influenza virus is not easily infected. Individual bird flu viruses that cause
human infections may have been mutated.
The possibility of mutation is that
more than two viruses enter the same cell for recombination. For example, pigs
can be infected with human influenza virus or avian influenza virus.
Each virus
has 8 gene fragments. In theory, it can form 256 new recombinant viruses. The
second is the virus gene locus due to certain factors.
In April 1983,
Pennsylvania and the United States had an outbreak of H5N2 virus-caused
low-pathogenic avian influenza in chickens and turkeys.
There was effective control, by
October of the same year, the same H5N2 strain suddenly changed from low
pathogenicity to high pathogenicity, causing a large number of poultry deaths.
Adaptability
Bird Flu viruses are sensitive to organic solvents
such as ether, chloroform and acetone. Commonly used disinfectants can easily
inactivate them, such as oxidants, dilute acids, sodium lauryl sulfate, halogen
compounds (such as bleach and iodine) can quickly destroy its infectivity.
Avian influenza virus is more sensitive to heat. It can be
inactivated by heating at 65 ° C for 30 minutes or boiling (100 ° C) for more
than 2 minutes.
The virus can survive for 1 week in feces and 1 month in water,
and has the ability to survive under pH <4.1. The virus has strong
resistance to low temperature resistance, and can maintain vitality for more
than 1 year when protected by glycerin.
The virus can be inactivated in direct sunlight for 40 to 48
hours, and if it is directly irradiated with ultraviolet rays, it can quickly
destroy its infectivity.
What is the Molecular characteristics of Bird Flu Virus?
Molecular Structure
Crystal structure of avian influenza virus polymerase
The widespread outbreak caused by the H5N1 subtype avian
influenza virus poses a major global threat to human health.
Due to the
constant mutation of viruses, the development of new anti-influenza drugs has
become an extremely urgent major issue in various countries.
Among them,
revealing the three-dimensional structure of proteins closely related to
influenza virus is not only of great scientific significance for revealing the
replication mechanism of influenza virus, but also of great value for the development
of anti-influenza virus drugs.
The research group led by the researcher Liu
Yingfang of the Institute of Biophysics, Chinese Academy of Sciences and the
research group led by academician Rao Zihe made breakthrough progress in this
field.
They were the first in the world to reveal the key part of influenza
virus polymerase PA subunit and PB1 polypeptide complex The fine
three-dimensional structure of the body.
Influenza A virus polymerase is composed of three
proteins-PA, PB1 and PB2, which is the key to transcription and replication.
Two groups reported the crystal structure of the C-terminal region of the avian
influenza virus H5N1 PA in the complex formed with the PA binding region of
PB1. This structural study may be useful for the design of new antiviral drugs.
The influenza virus genome contains 8 RNA fragments and is
known to encode 11 viral proteins. Among them, the polymerase complex composed
of PA, PB1 and PB23 subunits is a key component responsible for viral genome
RNA replication and viral mRNA transcription.
Also, because of its high
conservation and low mutation rate, it has become an anti-influenza virus drug
design Important target.
Over the years of research, PB1 is the catalytic
subunit of viral RNA polymerase, responsible for the replication and
transcription of viral RNA.
PB2 is responsible for capturing the host's CAP cap
structure in a manner called "Snatch" for viral mRNA transcription.
The PA sub-unit is not only involved in the process of viral replication, but
also participates in a variety of viral activities such as viral RNA
transcription, endonuclease activity, protease activity, and viral particle
assembly, so it appears exceptionally in the study of the entire polymerase
complex as important.
After screening crystal growth conditions, optimizing
crystal quality, high-resolution data collection, phase analysis, electron
density map interpretation, and structural correction, they used new ideas to
analyze the 2.9 angstroms of the PA-PB1 amino-terminal peptide protein complex.
Resolution crystal structure
The structure clearly shows the interaction mode
of PA and PB1 polypeptides, and it is found that the amino acid residues at the
action site are highly conserved in influenza viruses, which provides an ideal
for the research of broad-spectrum anti-influenza (including human influenza
and avian influenza) drugs Target protein.
At the same time, based on the
structure of the complex and the results of some known protein mutants, it is
speculated that the PA subunit plays a role in the polymerase, providing a
molecular basis for further functional studies.
The disclosure of the structure
of this complex is of great significance for revealing the mechanism of
influenza virus polymerase action and carrying out drug design work against influenza
virus.
Polymerase
It is a general term for a class of enzymes that specializes
in the biocatalytic synthesis of deoxyribonucleic acid (DNA) and ribonucleic
acid (RNA).
It can be divided into the following groups:
- DNA-dependent DNA polymerase.
- RNA-dependent DNA polymerase.
- DNA-dependent RNA polymerase.
- RNA-dependent RNA polymerase.
The first two are DNA
polymerases, which extend the DNA replication chain in the order of the
template. For example, in prokaryotes, only three types have been found in E.
coli (referred to as P01Ⅰ, P01Ⅱ and P01Ⅲ, etc.).
DNA polymerase can only
be based on primers, that is, 3 'of DNA or RNA primers. -OH extension, the
synthesis direction of this DNA is recorded as 5 '→ 3'. In other words, in
addition to the substrate (αNTP), the DNA polymerase catalyzed reaction also
requires Mg2 +, template DNA and primers.
So far, no synthesis of DNA from
monomers has been found in cells. Similarly, the above (3) and (4) are the most
important RNA synthetases in catalyzing RNA biosynthesis reactions. They use
four kinds of ribonucleoside triphosphates (NTPs) as substrates and require DNA
templates and Mn2 + and Mg2 +.
In the presence, the 3′-OH of the previous
nucleotide and the 5′-P of the next nucleotide polymerize to form a 3 ′,
5′-phosphodiester bond, and the direction of the nascent chain is also 5 ′ → 3
′.
RNA polymerase is also abundant in prokaryotic and eukaryotic cells. For
example, E. coli RNA polymerase has a molecular weight of 4.8 × 105 and is
composed of five polypeptide chains, which are named α, α, β, β' and γ,
respectively.
The total enzyme can be expressed by α2ββ′λ. The eukaryotic RNA
polymerase molecule is larger than 5 × 105, and is composed of 10-12 subunits
of different sizes. In addition to being an indispensable component of life
activities in nature, polymerase is mostly used as one of the enzymes in life
science research in the laboratory.
New H5N1
The United Nations Food and Agriculture Organization pointed
out on the 29th that H5N1, a highly pathogenic avian influenza virus that can
be transmitted to humans through poultry, has been spreading in recent years.
Lubrov, the chief veterinary official of FAO, pointed out that the spread of
H5N1 avian influenza virus has spread in recent years, and H5N1 variant viruses
have also appeared in China and Vietnam, which can make existing vaccines
useless.
He called on all countries to be prepared to closely monitor the virus
to prevent the spread of the epidemic.
Lubrov pointed out that bird migration is the culprit
responsible for the spread of the H5N1 avian influenza virus, and the
production and sale of poultry also contributed to the spread of H5N1.
He also
pointed out that in the past two years, the virus has spread through
long-distance migration of birds to countries that have eradicated the virus.
Lubrov also expressed concern about the H5N1 variant virus
that appeared in China and Vietnam. He pointed out that this mutant virus can
resist the effects of existing vaccines, and appealed to relevant countries not
to take it lightly, but to be fully prepared to monitor this virus.
Virologists warned on Tuesday that there is no vaccine to
prevent the H5N1 avian influenza variant strains circulating in China and
Vietnam, and called on all walks of life to strengthen surveillance of the
virus so as not to infect humans.
The veterinary department in Vietnam is highly vigilant and
is said to be considering a new and targeted vaccination campaign in the fall.
The spread of the virus in Vietnam directly threatens Cambodia, Thailand and
Malaysia, as well as the Korean Peninsula and Japan further away. The migration
of wild birds can also spread the virus to other continents.
The Food and Agriculture Organization of the United Nations
(FAO) warned on Monday that avian influenza may be swept up again, saying that
the H5N1 avian influenza variant strain is spreading in Asia and other regions.
Scientists are still not sure whether the new strain
H5N1-2.3.2.1 is more deadly to humans, but they point out that the strain is
very different from the original virus, and human vaccines against the original
virus are not effective.
Malik Peiris, a virologist at the University of Hong Kong,
said: "At present, the World Health Organization (WHO) has recommended a
human vaccine for H5N1. But it cannot be completely prevented (new strains).
"But this is very common. The H5 virus is constantly
changing, so we must also develop new vaccines to respond."
What is the Preventive Treatment against Bird Flu Virus?
Vaccine for Bird Flu Virus
Influenza virus vaccination is currently the first choice for
humans to prevent influenza. However, due to the large number of influenza
virus serotypes, once the antigenicity of influenza virus vaccine strains and
epidemic strains do not match, the vaccine will be invalid and unable to
provide corresponding protection.
At the same time because the rate of
influenza virus mutation is very fast, and the speed of vaccine development
lags behind the rate of virus mutation, after the emergence of new epidemic strains,
the preparation of the corresponding vaccine requires at least 6 months,
resulting in the preparation of the vaccine has been in a passive state. So
regardless of traditional Inactivated vaccines, genetic engineering vaccines,
nucleic acid vaccines and other new vaccines cannot provide cross protection
for all types of influenza viruses.
Inhibiting drugs
There are two main types of chemical drugs used to treat
influenza: one is ion channel inhibitors, that is, to target the ion channel
protein M2 of influenza virus, and to block the replication of influenza virus
by interfering with the activity of the ion channel protein of influenza virus
M2 protein.
There are greater toxic and side effects, and drug-resistant
strains have appeared.
The second is neuraminidase inhibitors, that is,
inhibitors that target the neuraminidase NA of influenza virus, which
effectively inhibits viral particles by inhibiting the activity of the enzyme.
Released on the surface of the host cell membrane, thereby
inhibiting the process of influenza virus infection of new host cells.
Drug-resistant strains of the drug have also appeared in patients infected with
H5N1 avian influenza virus. In addition, there are some artificially
synthesized sialic acid oligosaccharide analogs and single-flavor and compound
traditional Chinese medicine preparations that are resistant to influenza A
virus, but they are difficult to promote on a large scale for various reasons.
Treatment of poultry and bird flu: Guohao Yizhenling 1ml / kg + interferon +
cephalosporin pioneer, those who are seriously ill can use first aid interferon
to drink water.
 |
| Comparison Chart Analysis with Other Viruses and Flu |
What is the difference between Flu and Bird Flu?
Flu
is a contagious respiratory illness that RNA virus from the family
known as orthomyxoviridae causes. This affects birds as well as mammals.
While Bird Flu is caused by the influenza Type
viruses. It primarily infects birds and sometimes it can also transmit to human beings.
Macau Epidemic
On March 12, 2014, the Macau Civil Affairs Department
detected H7 avian influenza virus in live poultry samples from the wholesale
market. The authorities immediately took action.
On the morning of March 13,
2014, it began to culle more than 7,500 live poultry in the wholesale market.
Author's Bio
 |
| Dr. Shawna Reason |
Education: MBBS, MD
Occupation: Medical Doctor / Virologist
Specialization: Medical Science, Micro Biology / Virology, Natural Treatment
Experience: 15 Years as a Medical Practitioner
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