Prevention and treatment of viral diseases with specific immunotherapy

2021-08-25 05:47 PM

The above measures make a significant contribution to solving the viral disease, but the implementation requires a lot of effort and money

General perception

Preventive measures such as improved hygiene, improved drinking water, isolation of patients, sterilization of instruments and the environment, eradication of disease vectors, etc., are appropriately applied in each disease, each epidemic.

The above measures make a significant contribution to solving the viral disease, but the implementation requires a lot of effort and money. The method of killing vectors of disease transmission is an effective prevention measure.

Immunotherapy aims to strengthen the body's specific protective immunity against viral components. These include active immunotherapy, which is vaccination with antiviral vaccines, and passive immunotherapy, which is injections of immunoglobulins.

Active Immunotherapy

Antiviral vaccines, like all vaccines, are based on active stimulation of the immune system by the introduction into the body of antigens of infectious agents that have been rendered incapacitated to cause disease in humans. allows the body to build its own immunity against pathogens. The immune status that the body acquires after using a vaccine is the result of an immune response to the antigenic components contained in the vaccine.

The use of vaccines for disease prevention is a key way to reduce the incidence and mortality of viral infections. Viral vaccines in use today may include a live attenuated virus, inactivated virus, or viral structural components. The structural components of viruses can be made by recombinant DNA techniques or obtained from virions.

Inactivated vaccines (also known as dead vaccines)

This vaccine is produced by inactivating the virus with physicochemical agents such as heat, formol, beta propiolactone or ultraviolet light. As such, this vaccine consists of purified and killed virions, thus losing its ability to cause infection, losing its ability to cause disease.

Inactivated vaccines cause a good immune response when administered at the right dose and at the right time. It can be immunized in immunocompromised subjects as well as in pregnant women.

Inactivated vaccines generally do not provide lasting immunity compared with live attenuated vaccines and often require multiple injections to maintain immunity. This vaccine almost only stimulates the body to secrete anti-viral IgG and IgM in the blood. It therefore poorly inhibits entry of wild-type viruses into the gastrointestinal and respiratory mucosa, but it resists infection at the viremia stage if there is a disseminated infection.

Inactivated virus vaccines used for humans are influenza vaccine, rabies vaccine, polio vaccine (Salk vaccine), Japanese encephalitis vaccine, etc.

Another form of the inactivated vaccine (Subunit vaccine) contains only the most immunogenically important antigenic component of the purified and inactivated virions. For example, the hepatitis B vaccine is prepared from HBsAg present in the plasma of people infected with this antigen.

Live attenuated vaccines

This vaccine contains mutant viruses that have lost most of their virulence against humans. Vaccine viruses induce immunity but do not cause disease in humans, although their replication is limited in vaccinated individuals.

To produce this vaccine, it is necessary to use a strain of virus that is not capable of causing disease (different from the virulent wild virus strain) but is antigenically homologous or closely similar to the pathogenic wild virus in terms of antigenic structure.

The main feature of live attenuated vaccines is to induce in the body a process similar to that of natural infection, stimulating the body to respond to both systemic and local immunity, including humoral immunity. and cellular immunity. In particular, the stimulation at the entry point of the vaccine virus in the body produces a local protective immune response that mainly secretes the anti-viral IgA. For example, giving a live attenuated polio vaccine to children (Sabin vaccine) induces local immunity in the gastrointestinal mucosa, which prevents later entry of wild poliovirus into the gastrointestinal tract. chemical.

These vaccines also have the advantage of conferring a high degree of immunity and are long-lasting, usually only given once, and can be administered orally.

However, it is important to note that the safety of the live vaccine must ensure that it is no longer capable of causing disease or only causes very mild disease and the vaccine virus strain must have stable heritability and not mutate back to the original virulence. .

Live attenuated virus vaccines approved for use in humans include polio vaccine (Sabin vaccine), measles vaccine, mumps vaccine, Rubella vaccine, varicella vaccine, yellow fever vaccine, etc.

Recombinant Vaccines

A recombinant vaccine consisting of viral components produced by recombinant DNA technology. For example, the recombinant DNA vaccine for hepatitis B is prepared by molecular biotechnology and genetic engineering.

Another recombinant vaccine consists of a modified strain of the vaccine virus. That is, using recombinant DNA technology to add to the genetic material of the vaccine virus a gene that codes for the immunogenic component of a certain disease virus. As this vaccine virus grows in the host, a "foreign" gene product is also formed and immunity against both viruses is created. Recombinant vaccines of this type such as those against hepatitis B virus and immunodeficiency virus are being tested and evaluated for efficacy and safety.

Some vaccines against viral diseases are being used in Vietnam

Vaccination against polio

The polio vaccine being used in Vietnam belongs to a live attenuated vaccine, in the form of water for oral administration, named Sabin vaccine, consisting of 3 types of Sabin virus: type 1, type 2, and type 3, by the Center for Science and Technology. Sabin vaccine production is produced by our country. Sabin vaccine creates basic immunity for children under 1-year-old: 3 doses in the 2nd, 3rd and 4th months after birth. Each dose 2 drops (equivalent to 0.1 ml). Create additional immunity for children aged 0 - 5 years by taking 2 doses 1 month apart every year in polio vaccination campaigns.

Measles vaccine

The measles vaccine being used in our country is imported from abroad (France, Canada, Japan, India...). The measles vaccine is a live attenuated vaccine, in freeze-dried form. When used, the lyophilized vaccine is mixed with distilled water for injection under the skin of the arm with a dose of 0.5 ml for children 9 months to 11 months old.

Currently in many countries such as the US, Belgium, France, India, etc. measles vaccine is produced in the form of a triple vaccine against measles - mumps - rubella, with the brand name M - M -R. This is a live attenuated vaccine, lyophilized, injected subcutaneously or intramuscularly at a dose of 0.5ml for children between 12 months and 15 months of age.

Hepatitis B vaccine

Hepatitis B vaccine being used in Vietnam is manufactured by the Institute of Hygiene and Epidemiology (Hanoi) or imported from abroad such as Belgium, the US, Korea, etc. There are two types of hepatitis B vaccine: The first type (1st generation) is produced from the surface antigen (HBsAg) of hepatitis B virus present in the plasma of healthy people. The second type (2nd generation) produced from HBsAg was created by recombinant DNA technology performed on yeast cells. Hepatitis B vaccine in liquid form for vaccination of subjects including infants, older children, healthy people, people at high risk of hepatitis B virus infection. How to use hepatitis B vaccine according to the manufacturer's instructions vaccine production in each country.

Vaccine against Japanese Encephalitis

Vaccines against Japanese encephalitis are produced by the Institute of Hygiene and Epidemiology (Hanoi) or imported from abroad (Japan, Korea,). This is an inactivated virus vaccine, liquid form, injected under the skin with a dose of 0.5ml for children under 5 years old, with a dose of 1ml for children 5 years and older. Create basic immunity by injecting 3 doses:

+ The first dose: at the time of injection selection.

+ Second dose: 1-2 weeks after the first dose.

+ Third dose: 1 year after the first dose.

Should be injected before the month of the epidemic.

- Repeat injection:

+ Administer 1 dose per year in areas with endemic encephalitis. Should be injected in the month nearest to the month of the outbreak.

+ Four years of one dose in an area where there is no endemic encephalitis.

Rabies vaccine for humans

There are 2 types of rabies vaccines for human use in our country:

- Vietnam-made Fuenzalida rabies vaccine, lyophilized and liquid form, injected intradermally 6 doses every other day:

Over 15 years old: 0.2 ml each injection.

Under 15 years old: 0.1ml each injection.

Do not use immunosuppressive drugs such as ACTH, corticosteroids within 6 months after receiving the rabies vaccine.

French rabies vaccine Verorab is produced on Vero cells, lyophilized, injected subcutaneously or intramuscularly 5 doses, each dose 0.5ml on days: day 0 (time of injection), day 3, day 7, day 14, day 30. Optionally, repeat dose of 0.5ml on day 90.

Rabies vaccine should be given early to the victim of a dog (or cat) bite, after treating the bite site.

Vaccines are usually used to prevent disease, but vaccines can be given during the incubation period to treat viral diseases. For diseases with a long incubation period, such as rabies, vaccination is effective if administered immediately after infection with the virus.

Passive immunotherapy

Commonly used immunoglobulins are prepared from human serum and are divided into 2 types:

Normal immunoglobulin is also known as human serum immunoglobulin is prepared from the serum of all healthy individuals, without selectivity, so it contains antibodies against common viruses in the body. community. In fact, this serum is effective in preventing measles and hepatitis A.

Specific immunoglobulins are prepared from the serum of people who are recovering from certain infections, or those who have recently been vaccinated. Thanks to the appropriate selection of blood donors, in specific immunoglobulins, the concentration of antibodies against the virus that is the cause of the infection that the donor has had or has been vaccinated against is often tens of times higher than that of the blood donors. normal immunoglobulins.

In addition to immunoglobulins prepared from human serum, there are also immunoglobulins prepared from vaccinated animal serum to stimulate antibody production. Today, the use of animal serum is much reduced because the rate of causing a reaction is much higher than that of antibodies produced from human serum.

Antibodies that bind to viral proteins located on the outer surface of the virions can prevent the virions from being absorbed by virus-specific receptors on the cell surface.

There is strong evidence that giving immunoglobulins early in the incubation period can prevent or reduce the severity of many viral diseases, such as measles, chickenpox, viral hepatitis, rabies, smallpox, and smallpox. vaccines. Adequate immunoglobulins should be administered and given early before the viremia stage. Antibodies will take effect immediately after being injected into the body, but only for a short time, no more than 3 weeks