A Picture of Health By Holly Colquitt ViraldiseaseStructureAsingle virus cell is composed of an outer coat of protein which is called the capsid;this encloses the nucleic acid (either DNA or RNA) inside it. DNA(Deoxyribonucleic) is double stranded and more stable whereas RNA (Ribonucleic)is single stranded and more versatile. Virus cells do not have a cell wall, membraneor nucleus. Sometimes they have another membrane of lipid which is referredto as an envelope that surrounds the protein. The cell might also have a tailsection.
In general, a virus cell is muchsmaller than a bacteria cell is, most viruses are between 20 and 300nanometres, while a bacteria cell is roughly 50,000 nanometres.Routes of transmissionThemain way viruses are transmitted is through droplets like mucus from coughing,sneezing or spitting. As soon as they have entered the living host, they startthe process called replication;The first stage to this is the attachment; the virus startsto bind to the surface of the hosts cells. After the virus has bound to thecells it begins the next stage, Penetration, this is where the nucleic acidenters the cells. The next stage to this process is Synthesis of new components;once the nucleic acid has entered the cell it takes control of the cell metabolismwhich stops the cells normal nucleic acid and protein synthesis. Assembly isthe next stage of the transmission process and almost the final stage; it makeswhole virus particles, once the nucleic acids are fully surrounded by proteincoats.
The final stage is called release, this is when the cell has beenovertaken by the virus particles and bursts open, so the virus is then passedinto the bloodstream. How they grow and reproduceIt is only possible to reproduce while the virus isinside the cells of their host, which is destroying the cells in the process. Thevirus starts by entering the host’s cells and then starts to produce hundredsof thousands of copies of itself, after the virus produces so many copies andfills up the cell, it will burst and the virus will then be passed through and intothe host’s bloodstream.Animal viruses can be grown in natural growthvessels such as eggs, they have a sterile interior that is full of cells andnutrients the virus needs to grow and thrive. If a very small hole can be madethe virus can be injected through it, eventually it will begin to multiply.CanineParvovirusSymptomsSymptoms of the Canine Parvovirus include lethargy,depression, loss or lack of appetite then followed by a sudden onset of highfever, vomiting, diarrhoea and anorexia.TransmissionParvovirus can be transmittedin discharge from an infected dog, especially in their faeces or vomit; it canwithstand wide temperature changes and most cleaning products.Parvovirus can be brought into your home and transmitted to your dog viayour shoes, hands and even flies or birds.
Canine Parvovirus is a type ofvirus; it is shed in the faeces of infected dogs around 4 or 5 days afterexposure, throughout the period of the illness and for 10 days after clinicalrecovery. The infection is transmitted through oral or nasal contact withfaeces that contain the virus or through indirect contact withvirus-contaminated objects or materialsWhat does Canine Parvovirus do to the body cells?Once the virus has entered the dog, the CPV needs to find cellsthat are rapidly dividing in order to successfully cause and spread the disease,and then virus then tends to start by attacking the tonsils or lymph nodes inthe throat. Once the CPV is in the bloodstream, the virus then begins to targetthe rapidly dividing cells, mainly targeting in the bone marrow and in thecells that line wall of the small intestine.How does Canine Parvovirus grow and reproduce?Once they are inside the lymph nodes, the virus usuallybegins to invade the lymphocytes (which are a type of white blood cell) for oneto two days, and then creates many copies of itself. Once it has created the copiesit then hitches a ride on the lymphocytes to travel into the bloodstreambecause the lymphocytes shelter the virus from the host’s defences. When thevirus reaches the bloodstream, it begins to target the rapidly dividing cellsagain, mainly targeting the bone marrow and in the cells, that line the wallsof the small intestine.
FelineinfluenzaFeline influenza is similar to flu in humans, with similareffects and symptoms. If the cat is healthy it should be able to fight off theinfection with medical support, however in kittens and older cats, theinfection might harm them the most and proving fatal in some cases. SymptomsSymptoms of Feline influenza are usually that the cat seemslethargic, depressed, have a high temperature, lack of appetite and dischargefrom its eyes and nose.
TransmissionFeline Influenza (cat flu) is an infectious disease thataffects the upper respiratory tract. Direct contact with an infected cat canlead to infection however coughing and sneezing releases the virus into the airso sometimes direct physical contact is not required for the virus to bespread.What does Feline influenza do to the body cells?Once Influenza is introduced into the respiratory tract, itattaches to and replicates in epithelial cells, the virus replicates in cellsin both the upper and lower respiratory tract, the viral replication combinedwith the immune response to the infection leads to destruction and loss ofcells lining the respiratory tract. Once the virus infects the respiratoryepithelial cells, the single-stranded RNA of the influenza virus is recognisedby receptors. The receptor induces the production and activation of antiviralhost Reponses.
However, the virus can escape from the innate immune response byusing NS1 to interfere with the signalling. NS1 is a non-structural proteinwhich inhibits the production of interferon synthesis, allowing the virus toovercome the hosts defence system.How does Feline influenza grow and reproduce?For the virus to survive, they must reproduce while they areinside living cells. The genetic material from an infecting virus takes overthe functions of the host cell to make millions of new virus particles, the newviruses leave the host cell by bursting out of the cell or by budding out fromthe cell surface. Proteins on the virus attach to specific receptors on the surfaceof a host cell.
The virus may enter the cell by being engulfed by the cellmembrane or by fusing into the cell membrane FungalDiseaseStructureA fungal cell is made up of a hard cell wall, which is a rigid structure that provides the cell with support and protection.The cell wall structure also helps to prevent over-expansion when water entersthe cell.The cellmembrane, which is a biological membranethat separates the interior of the cell from the outside environment. The basic functionof thecell membrane is to protect the cell from its surroundings.
The cytoplasm is a gel-like substancethat fills cells. The cytoplasm contains and supports the cell’s organelles,transports genetic material within the cell and it also serves as a bufferprotecting the cell’s organelles and genetic material from damage due tomovement or collisions with other objects.The endoplasmic reticulum is a type of organelle foundin eukaryotic cells that forms an interconnected network of flattened, membrane-enclosedsacs or tube-like structures known as cisternae. The Golgiapparatus receives proteins and lipids(fats) from the rough endoplasmic reticulum. It modifies some of them andsorts, concentrates and packs them into sealed droplets called vesicles.A Vacuole is a membrane-bound organelle that is present in all plant and fungal cells and some animal and bacterial cells. The organelle has nobasic shape or size and its structure varies according to the needs of the cell. The cellnucleus is a structure inevery cell that contains its hereditary information and controls everythingthat happens in the cell including its growth and reproduction.
How they grow and reproduce Fungi can reproduce sexually and asexually. They formcells called spores, each fungi cell grows a single spore. These spores are neithermale nor female but like sperm or egg cells, they only contain one set ofchromosomes.
The spores then germinate into long fiber cells that are calledhyphae, once two hyphae’s meet the cell and nuclei fuse together. This resultsin a new set of chromosomes. The cells continue to divide which causes a thicklayer of hyphae to form, called mycelium. Impacts of different environment conditions on theirgrowth/reproductionHeat affects the growth of the fungi via the chemicals in the fungicells, for the best growth, the temperature needs to be in a range that allowsthe chemical reactions to work best in the cell. However, after the temperatureincreases above the ideal range, the chemical reactions will become lessefficient and the growth of the cell will begin to slow down. Once thetemperature gets to a high enough point, the cells will stop their growth andeventually become damaged. MicrosporumCanis (M.
canis)Microsporum Canis is a pathogenic fungus; it affects theupper and dead layers of skin on domesticated cats, and sometimes dogs andhumans. The infection occurs on the scalp and body sites, creating highlyinflammatory lesions associated with hair loss. The secretion of keratinolytic protease causes some damage tothe skin and hair follicle. The skin will have a hypersensitive reactionbecoming inflamed, which causes the fungus to move away from the site to normalskin. This creates characteristic circular lesions with healing at the centreand inflammation at the edge.SymptomsThe symptoms to look for include a poor coat, red skin,dandruff, scratching, hair loss and blister-like lesions.
TransmissionMicrosporum Canis is highly contagious and can be transmittedvia direct or physical contact, or through indirect contact with the fungus-contaminatedmaterials like brushes, furniture, linens etc.What doesMicrosporum Canis do to the body cells?Microsporum Canis Is found on the skin and in the fur,usually in domestic cats but is sometimes found in dogs and horses too. The fungus reproduces asexually and has thick cell walls that arerough in texture. How does MicrsporumCanis grow and reproduce?The animal’s immune system usually stops the fungus, howeverwhen a dog has the disease, or if on medication, the body is weakened andcannot fight the fungus on its own. The spores are very resistant when notgiven treatment, they can live up to two years. Spores attach to the skin andbegin to grow and produce hyphae (nutrient absorbing filaments), these thengrow in the dead layers of the skin, hair or nails.
Aspergillus spp.Aspergillosis is an opportunistic fungal infection caused bythe aspergillus, a species of common mold that is found throughout theenvironment, including dust straw, grass clippings and hay. An “opportunisticinfection” occurs when an organism, that does not usually cause disease,infects an animal. However, aspergillosis infects the animal because the immunesystem is weakened from another disease.SymptomsSymptoms of nasal aspergillosis include sneezing, nasal pain,bleeding from the nose, reduced appetite, swollen nose and long-term nasaldischarge which may contain mucus, pus or blood.TransmissionThere are two types of aspergillus infections, the first isthe nasal form, and this infection is localized in the nose, nasal passages andfront sinuses.
It is believed that it develops from direct contact with fungusthrough the nose and sinuses. For example, if a dog is outside and is arounddust or grass clippings, the fungus may enter through the moist lining of thenose.The second type of the infection is disseminated, meaningthat it is more widespread and is not only located in the nasal area, it is notcertain how disseminated enters the body. Acute invasive aspergillosis occurs when the immune systems fails toprevent Aspergillus spores from entering the bloodstream. Without the bodymounting an effective immune response, the fungal cells are free to disseminatethroughout the body.What does Aspergillus spp. do to the body cells?One of the characteristics of all fungi diseases are thenutritional strategies, the organisms secrete acids and enzymes into itssurrounding environment which then break down polymeric molecules down intosimpler ones that can then be absorbed back into the fungus cell. BacterialDiseaseStructure Bacterial cells are muchsmaller than plant or animal cells, they have a cell wall which is similar to aplant cell wall, only more flexible.
Bacteria cells donot have a nucleus.Bacteria cells have two typesof DNA; plasmid and chromosomal. The chromosomal DNA carries most ofthe cells genetic information and plasmid DNA forms small loops and carriesextra information. Some bacteria have a flagellum which is a whip like tail that helpsthe bacteria to move it along.Routes of transmissionThere are multiple routes possible for transmission;- Air droplet- Faecal-Oral- Open wounds- Mother to childAir droplets can be passed on bybeing inhaled, faecal-oral can be passed along through ingestion of faecal matteror through poor water and sanitation.
Open wounds can pass bacterial disease onthrough deep cuts or complications after giving birth such as an infectedumbilical cord and Mother to child transmission can be passed on through theirmilk or during the birth.Impacts of different environment conditions on theirgrowth/reproductionFood impacts the growth and reproduction of the bacterialcells because there is adequate nutrition available that help to promote thegrowth of the microorganisms. Foods such as meat, eggs, milk and fish are allrich in protein, therefor are the most vulnerable.The acidity is another condition that impacts the growth andreproduction because the foodborne pathogens require an acidic pH level between4.6 and 7.5, the best pH level for them to thrive in is between 6.6 and 7.
5. The temperature of the foodborne pathogens impacts theirgrowth and reproduction; they grow best between the temperatures of 41 to 135degrees Fahrenheit.Oxygen is another environmental condition that affects thereproduction and growth.
Almost all foodborne pathogens require oxygen to grow.Moisture is an environmental condition affecting the growthand reproduction, water is essential for the growth of foodborne pathogens, thewater activity (aw) is a measure of how much water is available; it ismeasured on a scale of 0 to 1.0. Foodborne pathogens tend to grow best in the aw of between0.95 to 1.0. SalmonellaSalmonella invades the healthy tissue of the host and beginsby reproducing and colonising.
It then produces extracellular substances whichhelp with invasion, giving the bacteria a chance to overcome the naturaldefence from the host.SymptomsThe symptoms of Salmonella develop diarrhoea, fever andvomiting. These symptoms usually occur 12 to 72 hours after infection.TransmissionBeing infected with the Salmonella enterica bacteria mainlyoccurs via ingestion of contaminated foodstuff, grass, wild birds and rats.
Occasionally food handlers also transmit theinfection.BordetellaBordetella,commonly known as kennel cough, is an infectious canine tracheobronchitis. Itis a highly contagious respiratory disease among dogs. Young puppies oftensuffer more severely, with complications that can result from this diseasesince their immune systems are immature. One of the first toxins to beexpressed is tracheal cytotoxin, this itself can paralyse cilia and inhibit DNAsynthesis in the epithelial cells and kill them. One of the most importantregulated toxins is adenylate cyclase toxin, which aids in the evasion ofinnate immunity; immune cell functions are then inhibited.
SymptomsSymptomsinclude a persistent cough, retching and watery nasal discharge. In mild cases,dogs are often active and still eating normally. In severe cases, symptomsprogress and can include pneumonia, fever, lethargy and even death. Dogs oftendevelop clinical signs associated with kennel cough 3-4 days after exposure toa large number of other dogs, for example, boarding facilities.
TransmissionTransmissioncan occur from direct contact or via respiratory aerosol droplets or fomites.The bacteria spread and then multiply to spread further into the respiratorytract, where the secretion of toxins causes the cilia to deactivate, allowingthe bacteria to enter the body Task BImmune systemTonsils- Are either of the two masseswith one on each side in the back of the throat, they are made up of lymphoidtissue. The Tonsils function is to trap bacteria and viruses that could beinhaled, the antibodies in the tonsils help to kill them to prevent throat andlung infections. Lymph Glands/Nodes- Are any of thesmall bean-shaped masses oftissue that are located along the vessels of thelymphatic system.
Their mainfunction is to drain out dead cells, bacteria, etc. by absorbing and expellingthe proteins. They also produce antibodies and lymphocytes.
Bone marrow- A soft substance that is foundinside the bones that produce blood cells. The main function of bone marrow isto produce red and white blood cells. Thymus- In juvenile animals, it produceslarge numbers of new T lymphocytes but when the animal matures this productiondecreases and T cell population is maintained by division of mature T cells. Ithas a key role in maturing prothymocytes into matured T cells. Thymus’s mainfunction is to receive T cells that are produced in the red bone marrow andthen turn them into functional T cells that can attack any foreign cells.
Spleen- Is an organ,located in the abdomen, that is involved in the production and the removal ofblood cells in most vertebrates. The spleen’s main function is tofilter blood of damaged cells, cellular debris, and pathogens such as bacteriaand viruses. Natural activeWhen the body meets an infection, it creates animmune response that produce antibodies and therefore fight off the infection. After the transmission from the infection occurs, the cell mediated, andhumoral mediated responses may start to become activate to help fight theinfection. Natural passiveWhen Infants are born, their immunesystems are immature, so therefore maternal antibodies must be transferredacross the placental barrier to the infant to enable an effective response topotential harmful pathogens. Some species have more layers within the placentalbarrier, which may affect the transfer of immunity.
For these species,colostrum (the first milk produced within 24 hours of birth) is essential. It isa mixture of highly concentrated antibody molecules, water, vitamins andnutrients. The antibodies are absorbed through the walls of the intestines afew hours of being born. The infant will only receive antibodies againstdiseases for which its mother had been recently vaccinated against or exposedtoArtificial activeIntroducing the antigen from an infectious agent and theninto the body to produce an immune response.
The antigens that are prepared in the vaccine help to stimulate theimmune system, so it can begin to produce antibodies and memory cells whichare specifically directedagainst the antigens in that vaccine. Once the body meets the living infectious agent, the memorycells start to generate an immune response, so they can quickly attack anddestroy the infection before the symptoms can even develop.Artificial passiveArtificial passive is a typeof immunity acquired by giving the animal or person an injection or transfusionof antibodies that work against infectious agents, however the protection willonly last a few weeks because the antibodies will slowly begin to break downand the immune system is not activated.DifferencesThe main difference between natural immunity and artificialimmunity is that natural immunity occurs naturally, without any interferencefrom a vet or health professional, etc. The difference between active andpassive is that ‘active’ requires the immune person to create the antibodiesthemselves, or ‘passive’, when they get them from somebody else.While artificial immunity occurs when the animal/person hasbeen artificially exposed to foreign antigens, this is active, or givenssomeone else’s antibodies, passively, to make an immune response to fight thedisease.ImmunityThere are three lines of immunity,Physical and chemical barriers, Non-specific immune response (innate) andSpecific immune responses (adaptive).
Innate ImmunityInnate immunity is Physical,chemical and cellulardefences that prevent microbes from entering the body. This quick-response system is effectiveagainst a wide range ofpathogens and foreign substances. Mast cells release histamine to the damaged tissue which causes acute inflammation; this increases blood flow tothat area which causesinflammatory response such as redness, heat, swelling, and pain.Adaptive immunityAdaptive immunity, which is often referred to as acquired immunity,is composed of highly specialized cells that eliminate pathogens and prevent their growth. Adaptive immunity creates immunological memory (which is asystem that quickly recognises the antigen that has entered the body, if it haspreviously encountered it) which leads to an enhanced response to the certainpathogen. Task CB cellsB cells (Blymphocytes) are a type of white blood cell. In mammals, B cells mature insidethe bone marrow.
B cells, unlike T cells and natural killer cells express Bcell receptors, which is a transmembrane receptor protein that is located onthe outer surface of the B cells. These allow the B cells to bind to a certainantigen; this will initiate an antibodyresponse. From the help of the T cells, B cells can make Y-shaped proteins,called antibodies. TcellsT cells are a type of lymphocyte thatplays an important role in cell-mediated immunity. T cells can be distinguishedfrom other lymphocytes by their T-cell receptors on the cell surface. Some Tcells send chemical instructions to the rest of the immune system so the bodycan create effective weapons against the bacteria, viruses or parasites cells.Other types of T cells can recognise and then kill cells that are infected bythe virus.
Whatdo B cells do inside the body?The antibodies that are produced, bind tothe antigens on the surface of the germs and stop them which create clumps inorder to alert the body of the intruders. The body begins to create toxicsubstances which fight them off and phagocytes immerse and destroy antibodycovered intruders.Whatdo T cells do inside the body?After the T cells have recognised thatthere is an invader and what the invader is, the send cytokines, chemicalinstructions, to the immune system in order for your body to kill the bacteria,virus or parasite.