General Microbiology Flashcards

Question

Virus structure: nucleocapsid and envelope?

Answer 1

Nucleocapsid: nucleic acid surrounded by protein coat (capsid) Icosahedral or helical shape of capsid (protein coat) Envelope: acquired by budding through cellular membranes, Glycoproteins on surface of envelope

Answer 2

Helical, polyhedral, complex Helical ex. RNA: Paramyxo, Rhabdo, Corona Complex: Poxvirus

Answer 3

Icosahedral i.e. DNA: Herpes, Parvo. RNA: Hepadna, Reto, Calici, Flavi, Picorna

Answer 4

Components: lipids, proteins, glycoproteins Properties: Labile in the environment, sensitive to acid, detergent, dying and heat, modifies cell membrane, released by budding and cell lysis Must be in moist conditions, spread in large droplets, secretions, transfusions, etc, do not survive adverse conditions (GIT), do not need lysis to spread within host, antibody alone may not provide immunoprotection (Cell mediated immunity- a response that does nto involve antibodies, but rather involves the activation of phagocytes, antigen specific cytotoxic T lymphocytes, and the release of various cytokines in reponse to an antigen) e.g. Herpes, Pox, Flavivuris, Togavirus, Coronavirus, Paramyxovirus

Answer 5

Components: proteins Properties: stable in the environment, insensitive to acid, detergent, drying and heat, released by cell lysis Can be spread easily, infective after drying, survive adverse conditions (inside GI), resistant to detergents, antibody may provide immunoprotection e.g. Parvo

Answer 6

Embryonated egg inoculation (lots ot time, labour, and difficult, but for an infectious virus) Cell culture (time, labour, difficult, but for an infectious virus) Polymerase Chain Reaction (rapid, specialized equip, quantatative, doesnt need infectious virus)

Answer 7

Fungi that can exist as mold/hyphal/filamentous form or as yeast. An example is Penicillium marneffei: At room temperature it grows as a mold, at body temperature it grows as a yeast.

Answer 8

Spores can generate another individual of the species. Any viable cell may be called a spore. Asexual or sexual reproduction.

Answer 9

Room temperature, fequently prolonged, aerobic, selective media, identification often morphological or cultural (colour, fruiting bodies). Easy to culture- think of yoghurt.

Answer 10

Wet mounts of tissue samples, histological specimin stained with periodic acid Schiff (PAS) or silver

Answer 11

Obligate aerobe, obligate anaerobe, microaerophilic (needs oxygen but poisoned by high concentrations of oxygen), facultative anaerobe, aerotolerant, enveloped or non-enveloped

Answer 12

Neutralisation assay, ELISA, HAI (hemagglutination assay)

Answer 13

An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria. Main purpose is to ensure the survival of the bacteria through tough environmental condition. IMPERVIOUS TO STAINS. Source of the organism. Bacillus and Clostridium species. No metabolic activity. Resistant to heat, drying, disinfectants, and radiation. Impervious to stains.

Answer 14

Targeted is better. WIth the broad spectrum, the bacteria that survive will have plenty of room to spread out and take hold.

Answer 15

\*Attachment: viral proteins bind to cell surface receptors \*Uptake of virus: by receptor of mediated endocytosis or by fusion with plasma membrane \*Uncoating: making viral genes available for transcription \*Early viral genes: shut down cellular protein synthesis, regulate expression of viral genome and production of enzymes (polymerase) \* Late viral genes: express structural proteins for virus assembly \*Enveloped viruses: acquire their envelope by budding through the plasma membrane, the cytoplasmic membranes or the nucleus membranes \* Non-enveloped viruses: accumulate in cytoplasm and are released when the cell lyses

Answer 16

In a live host, in an egg (amniotic cavity, yolk sac, allantois), in cell culture.

Answer 17

\*Bacterial adhesion: particularly important on mucosal surfaces \* often associated with pilli or fimbriae (what the bacteria uses to attach) \* Motility: flagellae (either polar or peritrichous)

Answer 18

\* Exotoxins- damage cell membrane, disrupt intracellular processes e.g. tetanus toxin by Clostridium tetani and botulinum toxin by Clostridium botulinum, Bacillus anthracis. \* enzymes- elastase, collagenase, proteinase, coagulase e.g. Pseudomona aeruginosa- cause damage to host tissues like DNAses which break down DNA \* Leucotoxins- disrupt the phago-lysosome (cytoplasmic body -fusion of a phagosome with a lysosome- after fusion the food particles contained within the phagosome are usually digested by the lysosome)

Answer 19

By virus infected calls, bacterial, or bacterial products.

Answer 20

1. Local spread- from cell to cell in close proximity to site of entry. Contiguous infection from adjacent cells. 2. Haematogenous spread- how does the virus get into the bloodstream? bite of an arthropod vector, iatrogenic- contaminated need, transfusion, etc, Primary replication- drainage to regional lymph nodes, thoracic duct, systemic circulation. Virus can be free in plasma or cell associated. (spin plasma or look at cells- making a diagnosis). Primary replication- low titre (i.e. with enteroviruses- in intestinal epithelium) Secondary replication- high titre (i.e. with enteroviruses- in lymphoid tissues, CNS) 3. Tissue invasion- mechanism that promote movement from vascular space to tissues is poorly understood. Often associated with infection of endothelial cells and/or passive transport across the endothelial cells. 4. Neural spread- virus moves to the nerve supplying the site of primary replication. Immune evasion strategy.

Answer 21

Mother to offspring- transmitting in utero or in ovo. Transmission across placenta, in birth canal, in colostrum/ milk. Cause embryonic death, mummification, resorption (time of gestation or congenital defects).

Answer 22

Direct contact- licking, rubbing, biting, sexual contact OR indirect contact (fomites)- feed and water containers, bedding, dander, tack, clothes, etc. Airborne, arthropod-borne transmission, iatrogenic transmission, nosocomial transmission, zoonotic

Answer 23

\* Goblet cells secrete mucus \* Gastric pH 2-3 \* Proteases secreted by gastric and pancreatic cells \* Bile salts \*Mucus containing IgA \* Mucocilliary clearance: mucus propelled and impinging particles propelled orad by ciliated columnar epithelial cells \* Humoral and cellular immune mechanisms operate locally \*IgA- in mucus (local immunity) tonsillar lymphoid tissue, alveolar macrophages, other phagocytes \*\* can establish local (confined to cells linging intestinal lumen) or systemic (cross intenstinal mucosa and invade underlying tissues and spread within the body) infections

Answer 24

Acid stable, resist degradation of bile salts, resist proteolytic inactivation. Parvo for example- infects the crypt cells. Outer protein coat of rotavirus virion is digested by trypsin in the small intestine. Coronaviruses are enveloped (exception to every rule)- but they are still GI viruses.

Answer 25

HIV, HSV-2, HPV. No effective physical barrier. Condoms. Bacterial cystitis.- urine flushing a protective mechanism.

Answer 26

Mammary gland- acute mastitis- via teat canal during or after milking. Umbilicus- neonatal sepsis. Conjunctiva- direct inoculation, usually local infection, very rarely spreads systemically.

Answer 27

\* Skin \* resp tract \* intestinal tract \* oropharynx \* conjunctiva \* urogenital tract \* mammary gland \* umbilicus- neonatal infections

Answer 28

No entry required. Botulism, tetanus, mycotoxicoses Toxins survive passage through intestine Direct effect on intestine or systemic effect

Answer 29

Most common route of infection. IgA- blocking adherence, export of invading organisms, intracellular neutralisation, opsonisation (flags it for the rest of the immune system). Good immune response prevents infection and therefore prevents disease. Primary vs. secondary responses.

Answer 30

Clinical signs are abnormalities detected during a physical examination (objective observations) while symptoms are a feature that indicates a conditon of disease, particularly a feature that is apparent to the patient

Answer 31

Infection is the growth (detection) of infectious agents in the body. Disease refers to organ or body system dysfunction (some loss of function).

Answer 32

Infectious disease is caused by infectious agents. Contagious disease is an infectious disease the can spread from one animal to another animal.

Answer 33

Take the history (single or multiple cases, duration, clinical signs, case definition, any treatment?), sample collection (sample from lesion affected, body system, aseptic collection technique, commensal or normal flora, sample methodology), transport to lab (obligate aerobes, obligate anaerobes, microaerophilic, facultative anaerobes, aerotolerant, enveloped or non-enveloped), diagnostic tests (agent: culture, electron microscopy, PCR, haemagglutination inhibition OR Ab detection: neutralisation assay, ELISA, HAI). CONSIDER: Normal flora of animal

Answer 34

Agglutination, precipitation, complement fixation, neutralisation, immunoassay

Answer 35

Culture (bacterial or viral), PCR, Agglutination, immunoassay, immunofluorescence, immunohistochemistry, FACS

Answer 36

Hypersensitivity, Blastogenesis assays, Cytokine assays

Answer 37

Antigen binding to antibody results in agglutination. No indicator system required. Mostly bacterial diseases. This is also the basis of the blood typing test.

Answer 38

Agglutination test for antibody

Answer 39

Virus neutralisation test. Relies on agent propagation in cell culture. Cell monolayer. Liquid growth medium. Filtered sample. Distermper, Parvo, etc. Unknown sample (with or without Abs) Cell controls- so if cells aren't growing well then assay isn't valid If cells are happy then we look at serum assay then we look at virus titration to see if it neutralizes a known amount of virus. Look at the virus conc. (do we have the right amount?)- then we can read it

Answer 40

Serum from an animal or person who has recuperated from a particular infection vs. serum from a patient with a current (acute) infection for which bacterial or viral specific immunoglobulins (usually IgM) are measured.

Answer 41

Infectious virus but it is time consuming, labour intensive, and technically difficult.

Answer 42

Melting- denaturing of the DNA duplex at a high temp to yield single stranded DNA Annealing- primers anneal to the single stranded target DNA sequence Elongation- DNA polymerase extends the primers by adding dNTPs to the phosphate backbone

Answer 43

\*collect lesions on live animals (dead animals undergo autolysis- early after death is better) \*minimize contamination \*Collect samples before antimicrobial administration \*Refrigeration \*Appropriate ID and OHS approved container/media

Answer 44

ENZYME LINKED IMMUNOSORBENT ASSAY For the detection of antibody-antigen interactions. For an ELISA designed to detect an antibody, the plate is coated with virus or viral antigen that is inactivated. Serum samples to be tested for the presence of antibody to the virus are then added to the virus- coated wells to allow for any specific anti-viral antibody to the serum to bind the virus. The remainder of the ELISA test is then the application of a colorimetric method that allows detection and quantification of the amount of antibody that is bound to the virus. \* the enzyme acts as an amplifier, even if only few enzyme linked antibodies remain bound, the enzyme molecules will produce many signal molecules. The more primary Ab is present in the donor serum, the more secondary Ab + enzyme will bind and the faster color will develop. e.g. Detection of antibodies for EHV4 and EHV1 (alphaherpesvirinae family)- closely related but cause different dieases. If you used the whole virus for EHV4 and EHV1 detection, you could not tell the test results apart for which virus. You must use smaller regions (glycoproteins in this case) that are strongly immunogenic and contain type specific epitopes. ELISA is the only test that can tell them apart.

Answer 45

Easy to administer, highly efficacious, one vaccination would provide life long protection, minimal side effects, safe to administer to all animals (young, old, pregnant), DIVA capacity (differentiated infecting vaccinated animals)

Answer 46

Non-replicating (need multi doses- no memory response)- inactivated viral vaccines, bacterins (inactivated bacteria), toxoids (inactivated toxins), recombinant proteins, direct DNA Replicating vaccines- attenuated viral vaccines, recombinant vector vaccines (more technologically advanced- what proteins are actually important? What gene encodes that protein? Use those. Etc.)

Answer 47

Immune response (memory cells) vs. Colostrum.

Answer 48

Extremely effective but quite a few issues associated. Can cross the barrier into the foetus in a pregnant animal. Unsafe for unhealthy, young, or old animals.

Answer 49

At least 3 times of vaccinating 4-6 weeks later. Especially a problem if disease is imminent and need for rapid onset of immunity.

Answer 50

(Differentiation between Infected and Vaccinated Animals) DIVA vaccines carry at least one epitopes less than the microorganisms circulating in the field. An accompanying diagnostic test that detects antibody against that epitope allows us to make that differentiation. Used to be called "marker" vaccines. \*\*Glycoproteins on the pathogen's envelope. When animal gets infected they mount a response to all of these proteins. It matters because if you are thinking about controlling the outbreak- then you cannot differentiate the animals who have been vaccinated or infected with blood tests- they would look the same.

Answer 51

Most common in veterinary medicine Advantages: safe and successful technology Disadvantages: reduced immunogenicity, boosters required, adjuvants required. \* Antibody mediated (TH2) response \*subunit vaccines and recombinant proteins

Answer 52

Circulating IgG is protective Tetanus and botulinum toxins Exotoxins are the issue and IgG is protective against

Answer 53

Hendra virus. G protein: Binds to host cell receptors. Initiates infection. So vaccine binds the G protein receptor instead.

Answer 54

Sufficient immune animals in herd to reduce the spread of infection, fewer suceptible, reduced excretion.

Answer 55

All animals in a particular geographic area that are susceptible will be vaccinated

Answer 56

Depends on mode of transmission will determine the radius.

Answer 57

Thinking about biosecurity (your own), is it contagious, is it a toxins, vaccination- do you vaccinate the herd that is affected or the ones next to affected? The ones next to the affected.

Answer 58

Chief Veterinary Officer (CVO unit)- sampling and testing, control and vaccination, eradication (+/- slaughter) \*Nat'l coordination \> 1 state \* animal health committee \*National management group \* Consultative Committee on EAD AUSVET PLAN

Answer 59

Containment and control based on: movement control, +/- vaccination, +/- regionalisation/ zoning

Answer 60

Transmission usually occurs through bites (scratching and licking can too). Virus replicates in muscle cells, very little virus replication in nerve cells, variable incubation period (weeks- years), bites around face, deep bites = shorter incubation period

Answer 61

1. Sylvatic (wildlife) rabies 2. urban (dog) rabies \* maintained when dog pop density \> 4.5 dogs/km^2 \* \>55,000 human deaths per annum \*\>95% of all human cases related to dog bites \*\>99% of human cases occur in Asia and Africa \* Majority of cases in children \<15 yo

Answer 62

\* 92% of reported cases were sylvatic rabies \*37% raccoons- of all animal cases \*23.5% skunks \*foxes- 7% Other wild animals- 1.8%

Answer 63

\* Important disease of farmed livestock \*Highly contagious \*Very high morbidity/low mortality \* Dramatic reduction in production (especially cattle) \* Disease of economic important (direct and trade)

Answer 64

\* Multiple host species, multiple modes of transmission, multiple serotypes, small infective dose, rapid replication, virus shedding before clinical signs, highly contagious, carrier state

Answer 65

1. Excrete FMDV up to 4 days prior to clinical signs 2. Incubation period \<14 days- index (2-3 day outbreak) 3. HIghly contagious- spready by aerosol, oral, fomites 4. Pigs are amplifier hosts 5. Cattle and sheep can be persistently infected 6. Sheep are often inapparent carriers 7. Vaccinated animals can be carriers, serologically indistinguishable from exposed animals

Answer 66

Chemoheterotrophs- an organism deriving energy by ingesting intermediates or building blocks that is incapable of creating its own (most chemoheterotrophs obtain energy by ingesting organic molecules like glucose)

Answer 67

Some bacteria, and all viruses will grow in animal cells. Often contain serum as an additive. Such as fetal bovine serum- the blood fraction remaining after natural coagulaton of the blood followed by centrifugation to remove any remaining blood cell lines. Why this one? It has a very low level of antibodies and contains more growth factors, allowing for versatility in many different cell culture applications.

Answer 68

Some microbial diseases are a result of the action of toxins. The organism itself may be located at a distant site of the body, or may not even have entered the animal's body. In these cases, diagnosis is often based on detecting the pathogen's protein (sometimes even if the pathogen detection is possible, it might be easier to detect the pathogen's proteins- say, if it is hard to culture).

Answer 69

An animal is inoculated with tissue, serum, or gut contents from a clinical case and a second animal is inoculated with the sample from the animal and a specific antitoxin. If the animal inoculated with the sample alone is affected and the animal administered antitoxin is not, the test is positive.

Answer 70

An antibody with the ability to neutralize a specific toxin. Antitoxins are produced by animals, plants, and bacteria. Examples are antitoxins to diphtheria and tetanus

Answer 71

Antibodies specific for proteins of the pathogen are labelled and applied directly to prepared tissue samples or smears. The antibody is generally conjugated to flourescein or horseradish peroxidase. AND you must add some sort of treatment to detect the label (incubation with a substrate for the enzyme). Whole organisms, or cells in which they have replicated, are specifically labelled.

Answer 72

Major cause of respiratory disease in young horses vs. EHV1 is the most important cause of viral abortion in mares, but it can also cause respiratory disease in foals. As they are herpes viruses, both EHV4 and EHV1 become latent in their host and can cause recurrent disease as a result of reactivation. \* Important to use ELISA to detect infected horses because of contagious potential for EHV1 storms.

Answer 73

Determine which horses are latently infected carriers of EHV1 so it can be effectively managed on stud farms AND To determine the cause of abortion where no foetal tissue samples can be obtained. Paired serum is obtained from the mare and taken about 10-14 days apart. A rise in antibody levels is indicative of recent infection with EHV1, or alternatively the absence of antibody means EHV1 was not the cause of the abortion.

Answer 74

Very high meaning they detect very small amounts of antibody in serum, possibly less than the amount required to neutralise the virus in an accompanying test.

Answer 75

All sites in the wells that are not coated with specific antigen need to be covered to prevent non-specific binding of other antigens which give false results. So you used a highly concentrated protein solution that is unrelated to the antigens in our test serums. You remove the blocking solution before the test of course.

Answer 76

the mean optical density. Seroconversion- Antibody becomes detectable in the blood (antibody in the blood \> the amount of antigen) \* use a spectrometer at a wavelength of 410nm O.D. \< 1: Negative O.D. between 0.1-0.2: Indeterminate (repeat test) O.D. \> 0.2 Positive

Answer 77

Direct ELISA- only one antibody is used and fewer steps required- used to test a specific antibody-to-antigen reaction and helps eliminate the cross reactivity between other antibodies (i.e. EHV4 and EHV1 could be misdiagnosed because they are so similar). Problem: The method of antigen immobilization is not specific: when serum is used as the source of test antigen, all proteins in the sample may stick to the microtiter plate well, so small concentrations of analyte in serum must compete with other serum proteins when binding the well surface. Indirect ELISA- In EHV4 and EHV1 example after you add the primary antibody, you add a secondary antibody directed against primary antibody (anti-horse, for example, goat antibody). Then you can add the color, the second antibody takes it up. This solves the problem with the Direct ELISA- the sandwhich ELISA- uses a "capture" antibody specific for the test antigen to pull it out of the serum's molecular mixture.

Answer 78

The growth of some bacterial species and all viruses can be blocked by specific antibodies directed against their surface proteins. Treatment of these pathogens with such antibodies before inoculation into culture can thus be used to identify them.

Answer 79

Some viruses can agglutinate red blood cells from particular animal species. The clumping of red blood cells by large numbers of virions can help identification. e.g. Neonatal Isoerythrolysis is a problem in foals that results from the passive transfer through colostrum of maternal antibodies capable of binding the foal's erythrocytes

Answer 80

You may measure antibody concentrations, cell mediated responses, or cytokine production. One test can only enable one to say that the animal has, at some time in its life, been infected. If you do two tests, one at the time of illness and several weeks later at the convalescent phase, an increase in response over this period indicates the infection has occurred recently. OR detection of recent immune response characteristics e.g. IgM Antibody concentrations & Cell mediated responses are the two ways

Answer 81

Inoculation of a small amount of protein from the organism, usually into the dermis, induces a migration of T cells and macrophages into the region. The swelling and redness can be detected a few days later. Cultures of lymphocytes in the presence of protein from an organism can also be used. If the animal has previously encountered the organism the memory response of the lymphocytes to the protein will stimulate their growth. You can also use an ELISA to detect the production of IL-2 by the stimulated lymphocytes.

Answer 82

Living freely in the environment- most bacteria and fungi e.g. Soil saprophyte- loss of epithelial integrity, immunocompromise, broad spectrum antimicrobial

Answer 83

Varies greatly between individuals and species with age, environment, nutrition, and location. Herbivores major part of digestion, other species it provides vitamins such as B & K. It can also breakdown potentially toxic products in food. Also by occupying a particular niche, competition for nutrients, inhibits potential pathogens. Places: mouth and nasopharynx, stomach (low numbers due to low pH), duodenum, jejunum and ileum, large intestine (high numbers), trachea, bronchi, lungs, vulva and prepuce, bagina, skin, mammary gland

Answer 84

Bacteriostatic agents prevent further multiplication but allow the organism to remain viable. While Bacteriocidal agents damage the cell irreversibly, so that further multiplication is not possible (such as nucleic acid damage or rupture of the virion or cell membrane). (Disinfectants must be bacteriocidal, chemotherapeutic agents can be either).

Answer 85

50C-70C for a few minutes. Most spores at 100C. e.g. Milk Pasteurisation- liquid held at 63C for 30 minutes or 72C for 15 seconds in flash pasteurisation. Removes 97-99% of bacteria thus slowing spoilage.

Answer 86

Heat sterilisation involves protein denaturation and melting of membrane lipids. Such disruption is aided by the presence of water to create hydrogen bonds with the separated molecules. Thus lower temperatures are necessary to sterilise wet material than dry material. Boiling is commonly used but some pathogens, such as Clostridium tetani (Tetanus) can survive several hours of boiling

Answer 87

Heating at 160C for 1 to 2 hours.

Answer 88

Conventional refrigerators are not adequate for preservation of bacteria but liquid nitrogen, solid CO2, or low temperature refrigerators can be used. Lyophilised (freeze dried) microorganisms can be stored at room temperature (many live vaccins are supplied lyophilised and are then reconstituted by adding water).

Answer 89

Strong oxidizing agent, toxic, used for sterilising gnotobiotic animal chambers

Answer 90

Oxidizing agent, not effective against many species due to possession of catalase (enzyme that catalyzes the decomposition of hydrogen peroxide to water and oxygen)

Answer 91

Cell culture: Time consuming, labour intensive, technically difficult, infectious virus, Cytopathic effect (CPE) PCR: Rapid diagnosis, specialized equipment, may be quantitative, doesn't need infectious virus (lab transportation considerations are less important- key because so many possible ways to kill a pathogen before analysis)

Answer 92

Organism remains infectious within the hostpial environment e.g. Parvovirus (environment), MRSA (staff and patients)

Answer 93

Refers to structural changes in the host cells that are caused by viral invasion. The infecting virus causes lysis of the host cell or when the cell dies without lysis due to an inability to reproduce. Common examples include rounding of the infected cell, fusion with adjacent cells to form synctyia (multi nucleated cell resulting from fusions of multiple uninuclear cells), and the appearance of nuclear or cytoplasmic inclusion bodies.

Answer 94

A way of expressing concentration. Titer testing employs serial dilution to obtain approximate quantitative information from a procedure that only evaluates as positive or negative. The TITRE corresponds to the HIGHEST dilution factor that still yield a POSITIVE READING. E.g. a Viral titre- which is the lowest concentration of virus that still infects cells. to determie the titre, several dilutions are prepared such as 10^-1, 10^-2, etc.

Answer 95

Transmission due to medical procedures such as injection or transplantation of infected material. e.g. Creutzfeldt Jakob Disease by injection of contaminated human growth hormone, or MRSA- stay in hospital

Answer 96

\> 5 microns- filtered by the turbinates \< 5 microns- lower respiratory tract

Answer 97

Local infections- confied to cells lining intestinal lumen OR Systemic infections- viruses cross intestinal mucosa and invade underlying tissues and spread within the body e.g. Rotaviruses and Coronaviruses- secretory and osmotic diarrhoea

Answer 98

Virus neutralization test. In the uninfected, the antibody has bound the pathogen and neutralized it. So the antibody is present. IN the infected, the pathogen has destroyed the cells- you are seeing a plaque.

Answer 99

First we look at cell controls- if the cells are growing okay and cells are healthy- then we move to look at the serum control- ensure it is not toxic (some serum is toxic to the cells, so our assay wouldn't read properly). Then we look at virus titration- work out what the concentration of the virus is- and if we have the right amount.

Answer 100

Essentially you are amplifying a single copy of a piece of DNA across several orders of magnitude, generating millions of copies of a particular DNA sequence. You can look at the genetic sequences of an agent to determine if it is a pathogenic strain or non-pathogenic, for example. You can also quantify the viral load in a patient. Require a thermal cycler. Melting: denaturing of the DNA duplex at a high temperature to yield a single stranded DNA. Annealing: primers anneal to the single stranded target DNA sequence. Elongation: DNA polymerase extends the primers by adding dNTPs to the phosphate backbone. (dNTPS are molecules containing nucleotide bound to two phosphates. Nucleotides are the building blocks of nucleic acids. NTP provides the energy and phosphate group for phosphorylations)

Answer 101

The goal with any vaccine is to develop one that is capable of inducing potent, persistent cellular immunity, and broadly reactive neutralizing antibody responses. Replicating recombinants can be better at eliciting specific cellular immune responses and better at priming humoral immunity compared to non-replicating recombinants carrying the same gene insert. Live viral vectors, such as adenovirus, as vaccine vehicles present one option for inducing more potent immunity. Non-replicating: inactivated viral vaccines (whole), bacterins (whole), toxoids (sub-unit), recombinant proteins, direct DNA Replicating vaccines: attenuated viral vaccines (vaccine created by reducing the virulence of a pathogen but still keeping it live), recombinant vector vaccines.