Avian adenovirus type C kind of 4 (FADV - C - 4)

Introduction to avian adenovirus species C, type 4 (FADV-C-4)

Avian adenovirus type C kind of 4 (FADV - C - 4) is a kind of no capsule membrane double-stranded DNA viruses, belong to the adenovirus family Adenovirudae Aviadenovirus avian adenovirus. The virus mainly infects broiler and layer hens aged 3-5 weeks. The clinical manifestation of the virus is mainly yellow or yellowish pericardial effusion, and in most cases is accompanied by hepatomegaly. Since July 2015, FADV - C - 4 in multiple areas of China small and medium-sized RouJiChang, DanJiChang flared, bring huge losses to China's poultry industry.

Mode of transmission and prevention and control measures

Avian adenovirus C type 4 can be spread through horizontal and vertical transmission. Horizontal transmission mainly through the digestive tract and respiratory tract infection, while vertical transmission can be transmitted to the next generation by chicken. In order to control the spread of the virus, it is suggested that take the following measures:

• Biosafety measures: strengthen the biosafety management of the farm, implement the all-in, all-out breeding mode, and thoroughly clean and disinfect the farm regularly.
• Immunization programs: choose to suit local disease prevalence of vaccine immunization, suggested that the conditional group of poultry immune at least two more times, poultry breeding cycle short use according to actual situation.
• Treatment: once found that chickens infected FADV - C - 4, should take immediate treatment measures, including the use of antiviral drugs and support therapy, to alleviate the symptoms and control the deterioration.

The latest research progress

Recent studies have shown that the separation and identification of FADV - C - 4 is vital for vaccine research and development. Through the study of the molecular biology of the virus isolated from the analysis, can better understand the virus's genetic characteristics and pathogenic mechanism, so as to help develop a more effective vaccines and treatments. In addition, the research also exploring the use of recombinant proteins and virus-like particle (VLP) as a potential vaccine, the results of this study is expected to vaccine development to provide a new direction for the future.

To sum up, avian adenovirus C type 4 is a serious threat to the poultry industry virus, through comprehensive prevention and control measures, and scientific research is needed to effectively control its spread and influence.

Avian adenovirus type C kind of 4 main clinical symptoms

Avian adenovirus type C kind of 4 (FAdV - 4) is a kind of virus can cause chicken disease, mainly for pericardial effusion - hepatitis syndrome (HHS). The virus infection usually leads to the following symptoms:

• Acute onset: the incubation period is shorter, the general is 1 ~ 2 days.
• The mental state change: sick chicken show is depressed, feather unkempt.
• Decreased appetite: reduced feed intake, sometimes even a complete cessation of eating.
• Difficulty breathing: may be accompanied by respiratory symptoms such as coughing and wheezing.
• Diarrhea: pull the yellow-green loose stool.
• Death: a short course of disease, mortality is high, especially in a young chicken is more apparent.

Autopsy change

Autopsy, the main pathological changes include:

• Hepatomegaly, hepatomegaly, yellow dye, sometimes accompanied by haemorrhage.
• Pericardial effusion: A large amount of yellow fluid accumulates in the pericardium and the heart softens.
• Kidney disease: kidney swelling, bleeding, sometimes with uric acid salt deposits.
• Other internal organs: The lungs may be congested, edematous, and bleed, sometimes with lung necrosis.

Prevention and control

Because of fowl adenovirus type C kind of 4 are highly contagious and can spread through vertical and horizontal transmission, therefore take effective measures and the biological safety of vaccination is very important. At present, the prevention of disease relies mainly on the whole virus inactivated vaccine inoculation, and live attenuated vaccines and subunit vaccines are also under development. In addition, regular monitoring and timely isolation sick chicken, feeding and strengthening management, can also help to control the spread of disease.

Routes of transmission of avian adenovirus C-4

Avian adenovirus type C kind of 4 (FAdV - 4) is a highly pathogenic virus, it can cause poultry pericardial effusion - liver splenomegaly syndrome (HHS), the disease spread rapidly in China since 2015, to the poultry industry brought huge economic losses.

Route of transmission

The main routes of transmission of FAdV-4 include:

• Horizontal transmission: FAdV - 4 can be horizontal transmission through the way such as respiratory, spread by droplets, for example, when sick birds coughing or sneezing, viruses can be transmitted to the other birds through the air.
• Direct contact between contact transmission: poultry, or through contact with contaminated by the virus objects or surfaces, and then touching their mouth, nose or eyes, is also one of FAdV - 4 mode of transmission.
• The fecal-oral transmission: FAdV - 4 can through the digestive tract infections, such as through the intake of contaminated feed or drinking water, this way of communication is particularly common in the chicks.
• Vertical transmission: FAdV - 4 can vertical transmission by chicken embryos, which means that the virus from infected hens to hatched chicks, and quickly spread in the new group.

The prevention and control measures

In order to effectively control the spread of FAdV - 4, it is suggested that take the following measures:

• Strengthen the biological security management, to avoid direct contact between poultry, especially in epidemic season.
• Regularly to cleaning and disinfection of farms, use effective disinfectant to eliminate the virus in the environment.
• The poultry seedling of newly introduced strict quarantine, to ensure that they have no FAdV - 4 with the virus.
• When necessary, can consider to use vaccine immunization, although there has not been specifically for the commercialization of the vaccine FAdV - 4, but researchers are working to research and development.

Combines the latest research results of the above information and industry experience, hope to be able to help you better understand FAdV - 4 transmission routes and prevention and control strategy.

Avian adenovirus type C kind of 4 vaccine development progress

Avian adenovirus type C kind of 4 (FAdV - 4) is a pathogen of causing serious disease of poultry, main cause hydropericardium - inclusion body hepatitis syndrome, is characterized by quick onset, high mortality rate. At present, the vaccine against FAdV - 4 mainly concentrated in several directions:

• Establishment of nucleic acid vaccine and immune effect evaluation: the researchers built a fowl adenovirus serum 4 type of nucleic acid vaccine, by prokaryotic and eukaryotic expression system for recombinant protein, and the immune effect is studied. The experimental results show that the vaccine could induce chickens to produce specific antibodies, antibody levels reached the highest in 21 days after the immune immune dose for 100 mu g effect is better.
• Inactivated vaccine development: researchers from suspected avian adenovirus infection chickens FAdV - 4 was isolated, identified and assessment of pathogenicity, chose to have good immunogenicity of JH strains as a potential vaccine strains. JH strains after dealing with the inactivated for immunogenicity test, the results show that induce the body to produce higher levels of neutralizing antibodies. In addition, JH plants have adapted to the cell culture, cultivate the virus after drop degree is high, suitable for as a potential vaccine strains.
• Subunit vaccine development: the researchers used FAdV - 4 strains of separation of whole genome analysis, and build the colloidal gold method, used for rapid diagnosis FAdV - 4 infection. At the same time, using separation of viral protein prokaryotic expression, and the preparation of the two-component subunit vaccine, the experimental results show that the vaccine can inhibit viral replication and the body's detoxification, alleviate pathological changes, provide 100% protection for chickens.
• Suspension culture technology applications: researchers to explore the efficient FAdV - 4 based on the technology of suspension culture inactivated vaccine preparation method, and the vaccine immune protection effect were evaluated. Results showed that the vaccine could provide up to 100% protection for chickens, and immune duration up to five months.

Progress of these studies suggest that vaccine development against FAdV - 4 is achieved positive results, the future is expected to provide effective technical support for the poultry epidemic prevention and control.