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Flashcards in Virology 3 Deck (49)
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1

5 Distinct Hepatitis Viruses

• hepatitis A virus • ______virus/___ ____ virus

• hepatitis B virus • ______virus/____ ____ virus

• hepatitis C virus • ___virus/___ ___virus

• hepatitis D virus (delta agent) • ____-like/___ ____

• hepatitis E virus • ____-like/___ ___ virus

5 Distinct Hepatitis Viruses

• hepatitis A virus • picornavirus/naked RNA virus

• hepatitis B virus • hepadnavirus/enveloped DNA virus

• hepatitis C virus • flavivirus/enveloped RNA virus

• hepatitis D virus (delta agent) • viroid-like/enveloped RNA

• hepatitis E virus • calicivirus-like/naked RNA virus

2

Characteristics of HAV

• picornavirus

• ____ to pH ___, ____solvents, detergents, saltwater, groundwater, drying, temperature

• inactivated by ___, ____, ___ ___

• Naked

Characteristics of HAV • picornavirus • stable to pH 1.0, organic solvents, detergents, saltwater, groundwater, drying, temperature • inactivated by chlorine, formalin, UV radiation • Naked

3

HAV Infection

• spread by ___-___ route; ___/____ outbreaks; dirty hands can spread it in food service industry

• ____ onset

• ____ disease

• no___ ___ or___ ___

• Symptoms are ___, ___, ___, ____ of ___, ___ ___

• ___--icteric phase (___% of adults; ____% of kids)

• Skin turns yellow • In darker people you see It in the sclera of their eyes

• symptoms due to___ ___ ___ ____

• immune response fighting off infection in the liver.

• Liver damage as a result of this but its totally___ ___ and goes away pretty quickly

• Recall: Enveloped virus is less stable because derived from cell membrane. Liquid. Requires cell in which to live. Generally not transmitted by door handles, they don’t survive very long in environment. • Naked: Protein is stable

HAV Infection • spread by fecal-oral route; food/waterborne outbreaks; dirty hands can spread it in food service industry • abrupt onset • mild disease • no chronic infection or carrier states • Symptoms are fever, fatigue, nausea, loss of appetite, abdominal pain • jaundice--icteric phase (>70% of adults; 10-20% of kids) • Skin turns yellow • In darker people you see It in the sclera of their eyes • symptoms due to immune-mediated liver damage • immune response fighting off infection in the liver. • Liver damage as a result of this but its totally self resolving and goes away pretty quickly • Recall: Enveloped virus is less stable because derived from cell membrane. Liquid. Requires cell in which to live. Generally not transmitted by door handles, they don’t survive very long in environment. • Naked: Protein is stable

4

Pathogenesis of HAV

___ Acquisition→Crosses ___→ ___→ ___→ ___→ ___ (____ virus particles/mL)

Pathogenesis of HAV Oral Acquisition→Crosses Intestines→ Blood→ Liver→ Bile→ Stool (10^8 virus particles/mL)

5

HAV Epidemiology

• HAV causes ___% of acute hepatitis

• most infected people are infectious____ symptoms occur • They don’t know it and they can spread it

• 90% of infected kids and 25-50% of infected adults have____,  but ____e infections • Don’t get sick but can spread virus

• outbreaks originate from a ___ ____ • All the pomegranate seeds in a shipment are contaminated

HAV Epidemiology • HAV causes 40% of acute hepatitis • most infected people are infectious before symptoms occur • They don’t know it and they can spread it • 90% of infected kids and 25-50% of infected adults have inapparent, but productive infections • Don’t get sick but can spread virus • outbreaks originate from a common source • All the pomegranate seeds in a shipment are contaminated

6

Reported number of cases Has been ____ since 2000

Reported number of cases Has been decreasing since 2000

7

Treatment and Control of HAV

• ___ ___ ____ 80-90% effective • For ___ ____ prophylaxis • Basically, ___ to the virus • ____ type of immunization

• ___ of ___ ___

• frequen ___ ___

 

• vaccine (licensed in 1995) • Havrix recommended by ___ yr of age •  ___ serotype • So easy to immunize against • infects __ ____ • Twinrix combo vaccine for age 18+ • Get booster before college

Treatment and Control of HAV • immune serum globulin 80-90% effective • For post exposure prophylaxis • Basically, Ab to the virus • Passive type of immunization • chlorination of drinking water • frequent hand-washing • vaccine (licensed in 1995) • Havrix recommended by 1 yr of age • only one serotype • So easy to immunize against • infects only humans • Twinrix combo vaccine for age 18+ • Get booster before college

8

HBV—Pathogenesis

• Much more complex virus

• You see it occurring in ___ ___  in the blood o Filamentous o Complete viral particle

• Lots of ___ and ___ Ag

• Infection with HBV→ increased levels of ___ ___ ___

• In an immune person, ___ will block any complications from that

• Most people will have symptoms and it will ___ ___

• During process of resolving infection, virus will spread by ____ • Will be in saliva, semen, vaginal secretions, blood and mothers milk

• Here again you can prevent spread of the disease with ___

• Problem is people who become ____ infected with Hep B

o Not much of a problem in the ____, vaccine world but plenty of people still carry the virus • Virus can be transmitted ___, ___, ___ and ___ ___

HBV—Pathogenesis • Much more complex virus • You see it occurring in many forms in the blood o Filamentous o Complete viral particle • Lots of enzymes and core Ag • Infection with HBV→ increased levels of HBV surface Ag • In an immune person, Ab will block any complications from that • Most people will have symptoms and it will resolve infection • During process of resolving infection, virus will spread by viremia • Will be in saliva, semen, vaginal secretions, blood and mothers milk • Here again you can prevent spread of the disease with Ab • Problem is people who become chronically infected with Hep B o Not much of a problem in the developed, vaccine world but plenty of people still carry the virus • Virus can be transmitted neonatally, blood, sexually and thru drug abuse

9

HBV Infection/Epidemiology

• parenteral (___ borne) and ___ ____ (thru mucous membranes)

• ____, insidious onset→ not as ___ as HAV

• fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, __ ___, ___ ___, jaundice • Signs/symptoms pretty much the same as HAV

• Can result in ___ ___ and ___ ___

• 800,000-1.4 million in U.S. have chronic infection

• 350 million worldwide have chronic infection

• 786,000 deaths annually worldwide from HBV-related liver disease

• Carriers can transmit it

• Associated with ___ ___ ____

• Liver is a regenerative tissue • As SC continue to replicate they become more sus to other damage to their DNA and you can get the formation of a tumor

HBV Infection/Epidemiology • parenteral (blood-borne) and sexual transmission (thru mucous membranes) • slow, insidious onset→ not as acute as HAV • fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, joint pain, jaundice • Signs/symptoms pretty much the same as HAV • Can result in chronic infection and carrier state • 800,000-1.4 million in U.S. have chronic infection • 350 million worldwide have chronic infection • 786,000 deaths annually worldwide from HBV-related liver disease • Carriers can transmit it • Associated with primary hepatocellular carcinoma • Liver is a regenerative tissue • As SC continue to replicate they become more sus to other damage to their DNA and you can get the formation of a tumor

10

Reported number of cases

____a huge problem in US anymore bc we have immunized against it.

Reported number of cases Not a huge problem in US anymore bc we have immunized against it.

11

HBV Carriers—

Worldwide Prevalence

Areas where hepatocellular carcinoma is also very prevalent

Developed world, ___________

HBV Carriers—Worldwide Prevalence Areas where hepatocellular carcinoma is also very prevalent Developed world, its not a problem

12

Transmission of HBV Modes

• ____ with an infected partner

• _____ drug use that involves sharing needles, syringes, or prep equipment

• ___ to an___ ___.

contact with ___ or ___ ___ of an infected person

• needle sticks or sharp instrument exposures

• sharing items like ___ or____ with an infected person

 

Risk Groups

• ___born to infected mothers

• __ ___ of infected persons

• sexually ____ individuals

• ___ who have sex with ___

• injection __ ___

•___ ___ of persons with chronic HBV infection

• ___ __ ___and public safety workers at risk for occupational exposure to blood or blood-contaminated body fluids

•_____ patients

• residents and staff or facilities for the ___ ___

___ to ____with intermediate or high prevalence of HBV infection

Transmission of HBV Modes • sex with an infected partner • injecting drug use that involves sharing needles, syringes, or prep equipment • birth to an infected mother • contact with blood or open sores of an infected person • needle sticks or sharp instrument exposures • sharing items like razors or toothbrushes with an infected person Risk Groups • infants born to infected mothers • sex partners of infected persons • sexually promiscuous individuals • men who have sex with men • injection drug users • household contacts of persons with chronic HBV infection • health care workers and public safety workers at risk for occupational exposure to blood or blood-contaminated body fluids • hemodialysis patients • residents and staff or facilities for the developmentally disabled • travelers to countries with intermediate or high prevalence of HBV infection

13

HBV Treatment/Vaccines

• ___ ____inhibitors

• ___ __ ___• Amped up with polyethylene glycol that makes it stick together better and be more effective and gives ___ ___

 

• vaccination

• ___ ___ Hep B vaccines (2)

• Vaccine used to be made with Hep B surface Ag that was purified from the plasma of infected people, but now we have the ____ vaccine

• ____ Vaccines (3)

HBV Treatment/Vaccines • reverse transcriptase inhibitors • pegylated α-interferon • Amped up with polyethylene glycol that makes it stick together better and be more effective and gives higher dose • vaccination • Single Ag Hep B vaccines (2) • Vaccine used to be made with Hep B surface Ag that was purified from the plasma of infected people, but now we have the recombinant vaccine • Combo Vaccines (3)

14

Hepatitis C Virus (HCV)

• Flavivirus—identified in ___; ___ genotypes o Analogous to west nile and others that are arthropod transmitted, but it is not transmitted that way

o Knowing which genotype person has can direct treatment

• Most infected people get ____ disease as opposed to ____ disease

• establishes ___-____, _____ infections leading generally to _____ disease (70%)

• accounts for ____% of cases of non-A non-B hepatitis; genotype  ___most prevalent

• HCV chronic disease (3.2 million Americans) ___ prevalent than ___ ____ disease (800,000-1.4 million Americans)

• prevalence worldwide is 2%=123,000,000 people

• ___ ___ for ___ ____

 o Bc so many people become chronically infected, their liver gets destroyed

• most ___ ___ ___ ____ in U.S. • The real problem in this family

Hepatitis C Virus (HCV) • Flavivirus—identified in 1989; 6 genotypes o Analogous to west nile and others that are arthropod transmitted, but it is not transmitted that way o Knowing which genotype person has can direct treatment • Most infected people get CHRONIC disease as opposed to acute disease • establishes non-cytolytic, persistent infections leading generally to chronic disease (70%) • accounts for 90% of cases of non-A non-B hepatitis; genotype 1 most prevalent • HCV chronic disease (3.2 million Americans) more prevalent than HBV chronic disease (800,000-1.4 million Americans) • prevalence worldwide is 2%=123,000,000 people • leading indication for liver transplantation o Bc so many people become chronically infected, their liver gets destroyed • most common blood-borne infection in U.S. • The real problem in this family

15

Pathogenesis of HCV

• viremia lasts ____ months in acute infection o During that time they are infectious. o This is longer duration that HAV, HBV acute

• viremia lasts ___ years in persistent infection

• ____ (immune response) leads to ___ ___ (liver)

• continual ___ ___ and induction of cell growth during __ ___ predisposes to liver cancer development

• _____ are ___ ____ so difficult to make a vaccine

• ____ ___ ___ blocks ___ of ___ ___ ___o Virus makes serine protease

• ____ _____ may prevent HCV from blocking interferon (Used in treatment of HCV)

Pathogenesis of HCV • viremia lasts 4-6 months in acute infection o During that time they are infectious. o This is longer duration that HAV, HBV acute • viremia lasts 10 years in persistent infection • CMI (immune response) leads to tissue damage (liver) • continual liver repair and induction of cell growth during chronic infection predisposes to liver cancer development • Antibodies are not protective so difficult to make a vaccine • HCV serine protease blocks activation of interferon regulatory factor o Virus makes serine protease • Protease inhibitors may prevent HCV from blocking interferon (Used in treatment of HCV)

16

HCV—

Transmission Modes

• ___ __ ____ (most common)

• needlestick injuries in __ ___ settings

• ____ to an HCV-infected mother

• inefficient modes

•___ with an HCV-infected person

• ____ personal items contaminated with infectious blood

• invasive health care____

Risk Groups

• current or former __ ___ ___

 • recipients of donated blood, blood products, and organs prior to ____ • It took us some time to get a test to screen for HCV

• ___ ___ ___ at risk for occupational exposure to blood or blood-contaminated body fluids

• persons with ____ infection • Bc of suppresed immune system

•___ ___ to  HCV-positive mothers

HCV—Transmission Modes • injection drug use (most common) • needlestick injuries in health care settings • birth to an HCV-infected mother • inefficient modes • sex with an HCV-infected person • sharing personal items contaminated with infectious blood • invasive health care procedures Risk Groups • current or former injection drug users • recipients of donated blood, blood products, and organs prior to 1992 • It took us some time to get a test to screen for HCV • health care workers at risk for occupational exposure to blood or blood-contaminated body fluids • persons with HIV infection • Bc of suppresed immune system • children born to HCV-positive mothers

17

Reported number of Acute HCV cases

____ for awhile but its been going __ ___

Still a major problem bc we have no way to __ ___other than being careful.

Reported number of Acute HCV cases Dipped for awhile but its been going back up Still a major problem bc we have no way to prevent transmission other than being careful.

18

Diagnosis and Control of HCV

• diagnosis based on detection of ____; seroconversion in ____ weeks; antibody ___ __ ___ in viremic people making serologic diagnosis of acute disease difficult

 

• Ab aren’t ___ but they are still an ___

• People will generally ____  over time but people who have viremia do not always have Ab, so difficult to diagnose using serology.

• ___ ___in serum better indicator • Test to look for RNA of virus in the serum

• controlled by ____ of blood supply and avoidance of ___ __ ___

Diagnosis and Control of HCV • diagnosis based on detection of antibody; seroconversion in 7-31 weeks; antibody not always present in viremic people making serologic diagnosis of acute disease difficult • Ab aren’t protective but they are still an indicator • People will generally seroconvert over time but people who have viremia do not always have Ab, so difficult to diagnose using serology. • virion RNA in serum better indicator • Test to look for RNA of virus in the serum • controlled by screening of blood supply and avoidance of high-risk behaviors

19

Treatment for Hepatitis C

• Considerations

• HCV ____

• __ ___→Serum RNA

• past ___

• degree of ___ ___

____status

 

• Drugs—combination therapies

• __ ___

• __ ___

• __ ___ • Interfere with repl of viral NA

• ___% cure rate • newer drugs very ____ Some say they are 90% effective in curing

Treatment for Hepatitis C • Considerations • HCV genotype • viral load→Serum RNA • past treatment • degree of liver damage • transplant status • Drugs—combination therapies • pegylated interferon • protease inhibitors • nucleoside analogues • Interfere with repl of viral NA • >80% cure rate • newer drugs very expensive Some say they are 90% effective in curing

20

Characteristics of HDV

• ___ ___genome surrounded by ___ ___

• ____ ____; essential for ____viru

s • Not much of a problem now bc most people are vaccinated against ____

 • Can only replicate in person who has __ ___

• It’s a different type of genome and has its own Ag (Delta Ag) but it’s in a coat of HBV surface Ag. That’s essential for packaging the virus. So you cant get HDV alone if you don’t have HBV

Characteristics of HDV • ss RNA genome surrounded by delta antigen • HBsAg envelope; essential for packaging virus • Not much of a problem now bc most people are vaccinated against HBV • Can only replicate in person who has HBV infection • It’s a different type of genome and has its own Ag (Delta Ag) but it’s in a coat of HBV surface Ag. That’s essential for packaging the virus. So you cant get HDV alone if you don’t have HBV

21

Pathogenesis of HDV

• replicates and causes disease only in those with active__ ___ •___-infection •___infection

• more ___, ___progression in HBV carriers

• causes direct ____ and __ ___

• immunization against HBV protects against HDV infection

In people who are carriers of HBV who then become infected with HDV, you can have more rapid, severe disease and it can be fatal

Pathogenesis of HDV • replicates and causes disease only in those with active HBV infection • co-infection • superinfection • more rapid, severe progression in HBV carriers • causes direct cytotoxicity and liver damage • immunization against HBV protects against HDV infection In people who are carriers of HBV who then become infected with HDV, you can have more rapid, severe disease and it can be fatal

22

Characteristics of HEV • calicivirus-like • Small naked RNA viruses

• ______spread like HAV • ___ ___ ___

• causes only ___ disease • ___ onset

• mild disease like HAV in normal patients, ____mortality than HAV

• We don’t know why

• Few people die from either HAV and HEV infection

 ____ prevalence in developed world, but nearly 3 million cases in developing world • A lot like HAV but member of different virus family (calicivirus)

Characteristics of HEV • calicivirus-like • Small naked RNA viruses • fecal-oral spread like HAV • contaminated drinking water • causes only acute disease • abrupt onset • mild disease like HAV in normal patients, higher mortality than HAV • We don’t know why • Few people die from either HAV and HEV infection • low prevalence in developed world, but nearly 3 million cases in developing world • A lot like HAV but member of different virus family (calicivirus)

23

•HIV ___ ____  virus

• envelope contains ___ ___; acquired by ____

 • capsid contains ____ identical copies of ___ strand RNA

• 10-50 copies of __ ___and ___ o In order to replicate it has to make a ___copy of the RNA so it has its own RT

• 2 cellular_____

• Tests to diagnose and moniter level of infection are directed at:

o ____—virion ___ protein

o___—___ protein

o ___—marker of a___ ___n

• Extremely important still • Complex virus

• enveloped RNA virus • envelope contains viral glycoproteins; acquired by budding • capsid contains two identical copies of + strand RNA • 10-50 copies of reverse transcriptase and integrase o In order to replicate it has to make a DNA copy of the RNA so it has its own RT • 2 cellular tRNA’s • Tests to diagnose and moniter level of infection are directed at: o gp120—virion attachment protein o gp41—fusion protein o p24—marker of active replication • Extremely important still • Complex virus

24

HIV Replication: RNA→ DNA→ RNA

1. Fusion of HIV to ___ __ ___

___ binds ___ Ag

Co receptors ___ or ____

Can infect mononuclear blood cells and lymphocytes

2. HIV ___, __, ____ and other viral proteins enter the host cell

3. Viral ___ is formed by __

4. Viral DNA is transported across the nucleus and ____ into the host DNA

5. New viral RNA is used as genomic RNA and to make___ ___s for assembly

6. New viral RNA and proteins move to the __ ___e and a new mature, HIV forms

7. The virus matures by ____ releasing individual HIV proteins

All these enzymes are good targets for drugs

HIV Replication: RNA→ DNA→ RNA 1. Fusion of HIV to host cell surface Gp120 binds CD4 Ag Co receptors CCR5 or CXCR4 Can infect mononuclear blood cells and lymphocytes 2. HIV RNA, RT, integrase and other viral proteins enter the host cell 3. Viral DNA is formed by RT 4. Viral DNA is transported across the nucleus and integrates into the host DNA 5. New viral RNA is used as genomic RNA and to make viral proteins for assembly 6. New viral RNA and proteins move to the cell surface and a new mature, HIV forms 7. The virus matures by protease releasing individual HIV proteins All these enzymes are good targets for drugs

25

HIV- Pathogenesis

• primary target cells are ____ cells and cells of the ____ lineage

• ___ infection of CD4+ T cells • Infects, virus replicates and kills the cell→ leads to low levels of CD4 • ____, ___-level ____ infection of macrophage lineage cells; _____ of the virus • Reservoir: Macrophage • Consistent low level of infection • Replicates

• Virus can cause ___ ____ (syncytia) formation

• alteration of T-cell and macrophage function

HIV- Pathogenesis • primary target cells are CD4+ T cells and cells of the macrophage lineage • lytic infection of CD4+ T cells • Infects, virus replicates and kills the cell→ leads to low levels of CD4 • persistent, low-level productive infection of macrophage lineage cells; reservoir of the virus • Reservoir: Macrophage • Consistent low level of infection • Replicates • Virus can cause multinucleated cells (syncytia) formation • alteration of T-cell and macrophage function

26

Staging of HIV Infection

• Acute HIV Infection • develops ___ weeks after infection • __ __e symptoms—fever, headache, rash • virus multiplies ___ and ____ hroughout the body • CD4+ cells ____ • ___ risk for transmission • Most don’t know that they have HIV

• Chronic HIV Infection • period of __ ___ • virus replicates at ___ ___ • usually ____ • transmission ____

 • AIDS • Sus to the___ ____ that kill people with HIV • Sus to ___ ___ (like KS) • CD4 count less than ____ cells/mm3

Staging of HIV Infection • Acute HIV Infection • develops 2-4 weeks after infection • flu-like symptoms—fever, headache, rash • virus multiplies rapidly and spreads throughout the body • CD4+ cells destroyed • highest risk for transmission • Most don’t know that they have HIV • Chronic HIV Infection • period of clinical latency • virus replicates at low levels • usually asymptomatic • transmission possible • AIDS • Sus to the opportunistic infections • that kill people with HIV • Sus to certain cancer (like KS) • CD4 count less than 200 cells/mm3

27

Time Course of HIV Infection

CD4 count ____s at beginning, then may ____ a little. During clinical latency, it just ___ ____

HIV RNA copies: After infection get a __ ___ in the viral load and then it comes ____ and then goes back ___p when have ___

Time Course of HIV Infection CD4 count drops at beginning, then may increase a little. During clinical latency, it just slowly decrease. HIV RNA copies: After infection get a huge boost in the viral load and then it comes down and then goes back up when have AIDS.

28

HIV Infection—Risk Factors

• engaging in ____d sex

• ___ sex more risky than vaginal sex

• having another ___—genital herpes, gonorrhea, chlamydia

• intravenous ___ ___ involving sharing of needles and syringes 

lack of ____ increases risk of heterosexual transmission

• exposure to the virus as a ___ or ____before or during birth or through ___from a mother infected with HIV

• receipt of a blood transfusion or clotting factor in the United States anytime from 1978 to ____

HIV Infection—Risk Factors • engaging in unprotected sex • anal sex more risky than vaginal sex • having another STD—genital herpes, gonorrhea, chlamydia • intravenous drug use involving sharing of needles and syringes • lack of circumcision increases risk of heterosexual transmission • exposure to the virus as a fetus or infant before or during birth or through breastfeeding from a mother infected with HIV • receipt of a blood transfusion or clotting factor in the United States anytime from 1978 to 1985

29

HIV—Transmission •

HIV __ ___ for very long outside of the body. (envelope virus)

• HIV cannot be transmitted through __ ___ __ such as using a toilet seat, sharing food utensils or drinking glasses, shaking hands, or through ____ 

• HIV can only be transmitted from person to person, not through ___ or __ ___.

• People infected with HIV who are taking_____  therapy can still __ ____ through unprotected sex and sharing needles and syringes. (Virus not completely eliminated from their body)

HIV—Transmission • HIV cannot survive for very long outside of the body. (envelope virus) • HIV cannot be transmitted through routine daily activities such as using a toilet seat, sharing food utensils or drinking glasses, shaking hands, or through kissing. • HIV can only be transmitted from person to person, not through animals or insect bites. • People infected with HIV who are taking antiretroviral therapy can still infect others through unprotected sex and sharing needles and syringes. (Virus not completely eliminated from their body)

30

HIV and Saliva

 

Only a small minority of HIV-infected individuals harbor the virus in ___ ___

HIV virions cannot live in a __ ___ state in saliva  (has to be in a cell to live)
(<1 infectious particle/ml of mixed saliva).

____ antibodies to p24, gp120, gp160 may neutralize infectivity.

____ entrap virus.

___ ___ __ ____  may block ___ ___ HIV ___

HIV loses infectivity when exposed to ___ saliva for ___ min.

Animal studies have shown that it is not possible to transmit HIV by ___ ___ to___ ___in contrast to vaginal mucosa.

 

HIV and Saliva

Only a small minority of HIV-infected individuals harbor the virus in whole saliva.

HIV virions cannot live in a cell-free state in saliva  (has to be in a cell to live)
(<1 infectious particle/ml of mixed saliva).

IgA antibodies to p24, gp120, gp160 may neutralize infectivity.

Mucins entrap virus.

Salivary leukocyte protease inhibitor (SLPI) may block cell surface HIV receptors.

HIV loses infectivity when exposed to mixed saliva for 30 min.

Animal studies have shown that it is not possible to transmit HIV by surface application to oral mucosa in contrast to vaginal mucosa.