How has Chlamydia trachomatis vaccine research evolved over the years. What are the main obstacles in developing an effective vaccine. Why is a vaccine crucial for controlling chlamydial infections. How do animal models contribute to vaccine development. What are the most promising vaccine candidates currently under investigation.

The Global Impact of Chlamydia Trachomatis Infections

Chlamydia trachomatis is a widespread sexually transmitted infection that poses significant health risks worldwide. According to the World Health Organization, millions of new cases are reported annually, making it one of the most prevalent bacterial sexually transmitted infections globally.

The impact of chlamydial infections extends beyond immediate health concerns:

• Increased risk of HIV transmission
• Potential for pelvic inflammatory disease in women
• Possible link to infertility in both men and women
• Complications during pregnancy and childbirth

Given these severe consequences, the development of an effective vaccine against Chlamydia trachomatis has become a priority in public health research.

Understanding Chlamydia Trachomatis: Pathogenesis and Immune Evasion

To develop an effective vaccine, researchers must first understand the complex mechanisms by which Chlamydia trachomatis infects and evades the host immune system. This bacterium has evolved sophisticated strategies to persist within host cells:

Cytotoxicity and Host Cell Manipulation

Chlamydia trachomatis produces cytotoxins that can damage host cells. These toxins, associated with complete and partial cytotoxin genes, play a crucial role in the bacterium’s ability to establish and maintain infection.

Interferon-γ Evasion

One of the key immune evasion tactics employed by Chlamydia trachomatis is its ability to evade the effects of interferon-γ (IFN-γ), a critical component of the host’s immune response. Different strains of the bacterium show varying levels of sensitivity to IFN-γ-mediated inhibition, complicating vaccine development efforts.

The Challenges of Developing a Chlamydia Vaccine

Despite decades of research, developing an effective vaccine against Chlamydia trachomatis remains elusive. Several factors contribute to this challenge:

• The intracellular nature of the bacterium, making it difficult for antibodies to reach
• The complex life cycle of Chlamydia, with different stages presenting varying antigens
• The bacterium’s ability to evade and modulate the host immune response
• Differences in immune responses between humans and animal models

These challenges have led researchers to explore various approaches in vaccine development, from whole-cell inactivated vaccines to subunit vaccines targeting specific chlamydial antigens.

Animal Models in Chlamydia Vaccine Research

Animal models play a crucial role in understanding chlamydial infections and testing potential vaccines. However, the translation of results from animal studies to human applications is not always straightforward.

Mouse Models: Strengths and Limitations

Mice are commonly used in Chlamydia research due to their cost-effectiveness and the availability of genetically modified strains. However, there are important differences between mouse and human infections:

• Chlamydia muridarum, a mouse-specific strain, is often used instead of human Chlamydia trachomatis strains
• The mouse immune response to chlamydial infection may not accurately reflect human immune responses
• The anatomy and physiology of the mouse genital tract differ from humans

Despite these limitations, mouse models have provided valuable insights into the immunology of chlamydial infections and potential vaccine strategies.

Promising Vaccine Candidates and Approaches

Research into Chlamydia vaccines has explored various strategies, each with its own advantages and challenges:

Subunit Vaccines

These vaccines target specific chlamydial antigens, such as the Major Outer Membrane Protein (MOMP). Advantages include safety and the ability to focus the immune response on protective antigens. However, they may not elicit a broad enough immune response to provide complete protection.

Live-Attenuated Vaccines

Live-attenuated strains of Chlamydia have shown promise in animal studies, eliciting strong cellular and humoral immune responses. However, safety concerns and the potential for reversion to virulence pose significant challenges.

DNA Vaccines

DNA vaccines encoding chlamydial antigens have demonstrated the ability to induce both cellular and humoral immunity in animal models. Their stability and ease of production make them an attractive option, but achieving sufficient immunogenicity in humans remains a challenge.

The Role of Immunology in Vaccine Development

Understanding the complex immunology of chlamydial infections is crucial for developing an effective vaccine. Key considerations include:

Cellular vs. Humoral Immunity

Both cellular (T cell-mediated) and humoral (antibody-mediated) immune responses play important roles in controlling chlamydial infections. An ideal vaccine would stimulate both arms of the immune system effectively.

Mucosal Immunity

Given that Chlamydia primarily infects mucosal surfaces, inducing strong mucosal immunity is crucial. This presents challenges in vaccine delivery and formulation to ensure adequate stimulation of mucosal immune responses.

Long-Term Protection

Developing a vaccine that provides long-lasting protection against chlamydial infection is essential. This requires a deeper understanding of immunological memory and how to effectively induce and maintain it in the context of Chlamydia.

Future Directions and Emerging Technologies

As research into Chlamydia vaccines continues, several promising avenues and technologies are emerging:

Systems Biology Approaches

Integrating large-scale data from genomics, proteomics, and immunology could provide new insights into chlamydial pathogenesis and host responses, informing vaccine design.

Nanoparticle-Based Vaccines

Nanoparticle technology offers the potential for improved antigen delivery and immune stimulation, potentially overcoming some of the challenges associated with traditional vaccine approaches.

Reverse Vaccinology

This computational approach to vaccine design, which starts with the genomic sequence of the pathogen to identify potential antigens, could accelerate the discovery of novel vaccine candidates for Chlamydia.

The Importance of Continued Research and Funding

Developing an effective vaccine against Chlamydia trachomatis remains a critical public health priority. Continued research and funding are essential to overcome the challenges and make progress towards this goal.

Key areas for ongoing focus include:

• Improving our understanding of chlamydial biology and host-pathogen interactions
• Refining animal models to better reflect human chlamydial infections
• Developing more effective adjuvants and delivery systems for chlamydial antigens
• Conducting well-designed clinical trials to evaluate promising vaccine candidates

By addressing these areas, researchers hope to make significant strides towards developing a safe and effective Chlamydia vaccine, potentially transforming global sexual health and reducing the burden of chlamydial infections worldwide.

Chlamydia trachomatis Vaccine Research through the Years

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A chlamydia vaccine shows signs of success in an early trial

CNN
 — 

Scientists have taken a step towards a vaccine for chlamydia following a successful early trial.

A vaccine developed by a British and Danish team was shown to be safe and effective during a randomized controlled trial involving 35 women, according to a study published in medical journal The Lancet Infectious Diseases.

Chlamydia is the most common bacterial sexually transmitted infection (STI) in the world. There are 131 million new cases every year, according to Imperial College London, with as many as three-quarters showing no symptoms. However it can cause infertility if left untreated.

The researchers, from Imperial College London, UK, and the Statens Serum Institut (SSI), Denmark, acknowledge that the development of the vaccine has a long way to go. It had however produced the immune response they had hoped for, and none of the women developed any serious side effects.

“The most important result is that we have seen protective antibodies against chlamydia in the genital tracts,” said study author Frank Follmann of SSI in a statement.

“Our initial trials show them preventing the chlamydia bacteria from penetrating the cells of the body. This means that we have come a lot closer to a vaccine against chlamydia.”

This is the first clinical trial for a vaccine for genital chlamydia and represents the latest development in 15 years of research, according to an SSI statement.

However there remains a lot of work to be done, according to study author Robin Shattock of Imperial College.

“The next step is to take the vaccine forward to further trials, but until that’s done, we won’t know whether it is truly protective or not,” he said in a statement from Imperial College.

Diagnostic tests and antibiotic treatments are available, but national treatment programs have had little effect in fighting the global chlamydia epidemic, according to press release from The Lancet. Study authors suggest a vaccine could be the best way to fight the infection.

PA6G5M Mycoplasma genitalium bacteria, illustration. It is a sexually transmitted organism that causes non-gonococcal urethritis in men and several inflammatory reproductive tract syndromes in women such as cervicitis, pelvic inflammatory disease, and infertility. As of 2018, its developing resistance to antibiotics means there are fears it may spread out of control as a ‘superbug’.

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Four emerging STDs that you can’t afford to ignore

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One million STDs diagnosed every day, World Health Organization says

One in every six women infected with chlamydia develops pelvic inflammatory disease, which can lead to chronic pelvic pain, ectopic pregnancy or infertility.

Chlamydia infection increases susceptibility to other STIs and infection during pregnancy increases the risk of miscarriage, stillbirth and preterm birth, according to the statement.

“Given the impact of the chlamydia epidemic on women’s health, reproductive health, infant health through vertical transmission, and increased susceptibility to other sexually transmitted diseases, a global unmet medical need exists for a vaccine against genital chlamydia,” said study author Peter Andersen of SSI.

Sarah Gilbert, a professor of vaccinology at the University of Oxford who was not involved in the study, said further research is needed as this trial looked primarily at the safety of the vaccine in healthy adults.

“More trials will be needed to find out if these immune responses are capable of preventing Chlamydia infection in people who have been exposed,” Gilbert told CNN.

It is not clear how soon a chlamydia vaccine could be used in the general population, according to Gilbert.

“It depends a lot on how much funding is available to continue with the vaccine development which will get more expensive at every stage,” said Gilbert.

While it is scientifically possible for a vaccine to be made available in five years, it is common for vaccines to spend 10 or 20 years in development, she explained.

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It also depends on the manufacturing capacity of SSI, which produced the vaccine used in the trial.

“Will they be able to manufacture enough for the vaccine to be marketed, or will it need to be transferred to another manufacturer?” said Gilbert.

“That will have implications for the time to vaccine licensure.”

In June, the World Health Organization (WHO) released figures showing more than one million new cases of STIs are contracted every day.

The four infections are chlamydia, gonorrhea, trichomoniasis (or “trich”) and syphilis.

An average of one in every 25 people globally has at least one of these STIs, according to the WHO.

ChlamydioVac – Uralbiovet

Chlamydia Vaccine in Animals ChlamydioVac is a drug in the form of an injectable emulsion (inactivated vaccine) for the prevention of chlamydia in animals.

Vaccination is subject to clinically healthy population of animals from 1 month and older. The vaccine is administered once a year once subcutaneously: in sheep and goats – in the upper third of the neck, in pigs – in the area behind the ear, in cattle – in the dewlap area.

INSTRUCTIONS for veterinary use of the vaccine against chlamydia in animals “ChlamydioVac”

I. General information
1. International non-proprietary name – Animal chlamydia vaccine “ChlamydioVac”.
Trade name: Animal chlamydia vaccine
ChlamydioVac.
2. Dosage form – injection emulsion (inactivated vaccine).
The vaccine is made from a suspension of chlamydia Chlamidophila psittaci “Armavir” and “SBYa-2” in a titer of at least 10, inactivated with formalin, with the addition of an oil adjuvant.
3. In appearance, the vaccine is a pale pink emulsion with a viscous consistency. During long-term storage in the lower part of the bottle, a slight stratification of mineral oil is possible, which disappears when shaken.
Shelf life of the vaccine is 12 months from the date of issue, subject to the conditions of storage and transportation. After the expiration date, the vaccine is not suitable for use.
After the first opening of the vial, the vaccine must be used within 12 hours.
4. The vaccine is packaged in 100 cm3 (100 doses), 200 cm3 (200 doses) vials of appropriate capacity, sealed with rubber stoppers reinforced with aluminum caps.
Vaccine vials are packaged in corrugated cardboard boxes to ensure their integrity. Each box contains at least 3 copies of instructions for use
5. The vaccine is stored and transported in the manufacturer’s packaging in a place protected from light at a temperature of 2°C to 10°C.
6. Keep the vaccine out of the reach of children.
7. Vaccine in unlabeled vials, with broken integrity and/or tightness of the closure, with a changed color and/or consistency of the content, with the presence of foreign impurities, expired, frozen, as well as the remains of the vaccine, unused within 12 hours after the first opening of the vial, they are to be discarded and disinfected by boiling for 30 minutes and disposed of.
Disposal of decontaminated vaccine does not require special precautions.
8. The vaccine is available without a prescription from a veterinarian.
II. Biological properties
9. Pharmacotherapeutic group: immunobiological medicinal products for veterinary use.
10. The vaccine causes the formation of an immune response in cattle, sheep, goats, pigs to chlamydia in 20-25 days after a single application for 12 months.
1.0 cm3 of the vaccine contains a suspension of inactivated Chlamydia Chlamydophila psittaci “Armavir” and “SBYa-2” in a titre of at least 107
The vaccine is harmless, has no medicinal properties.

III. How to use
11. The vaccine is intended for the prevention of chlamydia in farm animals in disadvantaged or endangered farms.
12. Do not vaccinate clinically ill and/or debilitated animals.
13. When working with a vaccine, you should follow the general rules of asepsis, personal hygiene and safety precautions provided for when working with medicinal products for veterinary use.
All persons involved in the vaccination must be dressed in overalls (rubber boots, overalls, trousers, headgear, rubber gloves, etc. ) and provided with personal protective equipment (closed-type goggles, respirators).
A first aid kit must be available at work sites.
People with hypersensitivity to the components of the drug should avoid direct contact with the vaccine.
If the vaccine comes into contact with the skin and/or mucous membranes, wash them with plenty of water.
In case of accidental administration of the vaccine to a person, the injection site must be treated with a 5% iodine solution or a 70% ethanol solution and contact a medical facility.
In case of allergic reactions or in case of accidental ingestion of the drug into the human body, you should immediately contact a medical institution (have the instructions for use of the drug or a label with you).
Empty vaccine vials should not be used for household purposes and should be disposed of with household waste.
14. Vaccination is subject to clinically healthy livestock from 1 month and older.
Pregnancy vaccine may be used no later than one month before the end of pregnancy.
The use of the vaccine in animals during lactation does not cause side effects and complications.
15. The vaccine is administered once a year once a year subcutaneously: in sheep and goats – in the upper third of the neck, in pigs – in the area behind the ear, in cattle – in the dewlap area in the following doses:

Before use, the vaccine is heated in a water bath at a temperature of 36-37°C and periodically shaken during vaccination.
Syringes and needles are sterilized by boiling. A separate sterile needle is used to vaccinate each animal. The injection site is disinfected with 70% ethyl alcohol or another disinfectant solution.
16. When using the vaccine in accordance with this instruction, side effects and complications, as a rule, are not noted. In some cases, a slight swelling may form at the injection site, which disappears within 21 days and, as a rule, does not require medical intervention.
17. Symptoms of the manifestation of clinical signs of chlamydia in animals with an overdose of the vaccine have not been established.
18. Do not use the vaccine in conjunction with other live immunobiological preparations, as well as within 7 days before and 14 days after deworming.
19. Features of post-vaccination reactions during primary or repeated immunization and vaccine withdrawal have not been established.
20. Violations of the schedule (timing) of vaccination should be avoided, as this may lead to a decrease in the effectiveness of chlamydia immunoprophylaxis. In case of missing the next injection of the vaccine, it is necessary to carry out immunization as soon as possible.
21. Slaughter products of vaccinated animals are sold without restrictions, regardless of the timing of vaccination. In case of forced slaughter of animals with signs of post-vaccination reactions, they are guided by the “Rules for the veterinary examination of slaughter animals and the veterinary and sanitary examination of meat and meat products” (Vet. Pin 13.7.1-99 p. 10).
Milk and slaughter products obtained from vaccinated animals are used without restrictions, regardless of the timing of vaccination.

Buy in the Sverdlovsk region “Chlamydiovac” is available from a warehouse in Yekaterinburg, Irbit. In Chelyabinsk, Perm, Tyumen, Ufa, Kazan, Izhevsk, you can buy “Chlamydiovac” in our branches. Addresses and phone numbers of the warehouse in Yekaterinburg and our branches in the contacts section. Instructions for preparations on the site are provided for informational purposes only, and cannot be used as a guide or recommendation for use. Up-to-date instructions will be provided to you when purchasing the drug. The type of packaging / container and label of the drug may differ from the image on the site.

🕔16:21, 20.Sep 2021

Tags: bovine vaccinespigs

Chlamydia vaccines show safety in first clinical trials

Human studies have demonstrated the safety of two new vaccines against chlamydia, one of the most common sexually transmitted diseases. Both have successfully passed the first phase of clinical trials, showing their immunogenicity and the absence of side effects, reported in the journal Lancet Infectious Diseases .

Bacteria Chlamidia trachomatis are transmitted from person to person sexually and provoke diseases of the genitourinary system. In many cases, chlamydia is almost asymptomatic, but it can cause serious complications and is dangerous during pregnancy. The “quiet” lifestyle of bacteria allows them to remain unnoticed in the body for a long time, so many people begin treatment with a great delay. This allowed chlamydia to become one of the most common sexually transmitted diseases – according to WHO estimates, in 2016 alone, 127 million people fell ill with it worldwide. Chlamydia is treated with antibiotics, but for the above reasons, this does not slow down the general spread of the infection, so the development of preventive methods of protection against this disease, including vaccines, is very relevant.

Sonya Abraham and her colleagues recently successfully completed Phase 1 clinical trials of vaccines. The study took place at the Hammersmith Hospital in London on 35 subjects: two groups of 15 healthy women tested two versions of the vaccine, and five more were in the control group. They all received three injections for four months, and then two more doses in the form of a nasal spray, and neither the subjects nor the doctors knew who belonged to which group. The study did not reveal any serious side effects, and the problems found, such as pain from injections, were mostly distributed among all three groups.