2. CONTENTS…
• Retroviruses
• Terminology and definitions
• History
• Morphology
• Signs and symptoms
• Epidemiology
• Pathogenesis
• Treatment
• Prevention
3. RETROVIRUSES
• These are RNA viruses that belong to family retroviridae
• Members of this family possess reverse transcriptase(RNA
directed DNA polymerase) enzyme which prepares a DNA copy of
the RNA genome in the host cell
• discovered independently in 1971 by American virologists Howard
Temin and David Baltimore
• The presence of enzyme reverse transcriptase is a characteristic
feature
5. • Infection: infection is the entry and development or multiplication of an infectious
agent in the body of man or animals.
• Contamination : The presence of an infectious agent on a body surface
• Infestation: is the state of being invaded or overrun by pests or parasites. It can
also refer to the actual organisms living on or within a host.
• Host : A person or an animal that affords subsistence or lodgement to an infectious
agent under natural conditions.
• Contagious disease :A contagious disease is the one that is transmitted through
contact.
• Epidemic: An epidemic is the rapid spread of infectious disease to a large number
of people in a given population within a short period of time, usually two weeks or
less.
6. • Endemic: It refers to the constant presence of a disease or infectious agent within
a given geographic area or population group.
• Pandemic: A pandemic is an epidemic of infectious disease that has spread
across a large region; for instance multiple continents, or even worldwide
• Sporadic: occasional cases occuring in regular intervals
• Zoonosis : is an infection that is transmissible under natural conditions from
vertebrate animals to man
• Epizootic: is an outbreak (epidemic) of disease in an animal population, e.g. Rift
valley fever, Anthrax.
• Enzootic: is an endemic occurring in animals, e.g. Bovine TB.
7. • Exotic: diseases are those which are imported into a country in which they do
not otherwise occur, as for e.g., rabies in the UK, Yellow fever in India,
• Nosocomial infections : (hospital acquired) is an infection originating in a patient
while in a hospital or another health care facility.
• Opportunistic infection : This is infection by organisms that take the opportunity
provided by a defect in host defense (e.g. immunity) to infect the host and thus
cause disease
• Pathogenesis: The development of a disease and the chain of events leading to
that disease.
• Epidemiology : is the study and analysis of the distribution and determinants of
health and disease conditions in defined populations
9. The link between HIV and SIV?
Did HIV come from monkeys?
How did HIV cross from chimps to humans?
How did HIV-2 get passed to humans?
When and where did HIV start in humans?
Did HIV start in Africa?
How did HIV spread from Kinshasa?
What happened in the 1980s in the USA?
What is HIV?
Where did AIDS come from?
10. • HIV is a type of lentivirus, which means it attacks the immune system.
• In a similar way, the Simian Immunodeficiency Virus (SIV) attacks the immune systems of
monkeys and apes.
• Research found that HIV is related to SIV and there are many similarities between the two
viruses.
• HIV-1 is closely related to a strain of SIV found in chimpanzees, and HIV-2 is closely related to a
strain of SIV found in sooty mangabeys.
• They discovered that the chimps had hunted and eaten two smaller species of monkeys (red-
capped mangabeys and greater spot-nosed monkeys).
• These smaller monkeys infected the chimps with two different strains of SIV.
• The two different SIV strains then joined together to form a third virus (SIVcpz) that could be
passed on to other chimps. This is the strain that can also infect humans.
11. • The most commonly accepted theory is that of the 'hunter'.
• SIVcpz was transferred to humans as a result of chimps being killed and eaten,
or their blood getting into cuts or wounds on people in the course of hunting.
• There are four main groups of HIV strains (M, N, O and P), each with a slightly
different genetic make-up.
• HIV-2 comes from SIVsmm in sooty mangabey monkeys rather than
chimpanzees.
• The crossover to humans is believed to have happened in a similar way
(consumption of monkey meat).
• It is far rarer, and less infectious than HIV-1.
13. • . The first verified case of HIV is from a blood sample taken in 1959 from a man
living in what is now Kinshasa in the Democratic Republic of Congo. The
sample was retrospectively analysed and HIV detected.
• the first transmission of SIV to HIV in humans took place around 1920 in
Kinshasa in the Democratic Republic of Congo
• In 1981, a few cases of rare diseases were being reported among gay men in
New York and California, such as Kaposi's Sarcoma (a rare cancer) and a
lung infection called PCP.
14. • At first the disease was called all sorts of names relating to the word 'gay'.
• scientists realised the 'disease' was also spreading among other populations such as
haemophiliacs and heroin users.
• By September that year, the 'disease' was finally named AIDS.
• It was only in 1983 Luc Montagnier and colleagues from the pasteur institive paris isolated a
retrovirus from a west african patient with persistent generalised lymphadenopathy which is a
manigestatin of AIDS and called it lymphadenopathy associated virus (LAV)
• In 1984 Robert gallo and colleagues from the national institutes of health reported the isolation
of a retrovirus from AIDS patients and called it human T cell lymphotropic virus III
• International committee on virus nomenclature in 1986 decided on the generic name human
immunodeficiency virus for those viruses
15. CLASSIFICATION
• Family : Retroviridae
• Subfamily : Orthoretrovirinae
• Genus : Lentivirus
• Species : HIV 1 / HIV 2
• HIV 1- Isolated in America, Europe & central Africa
• HIV 2- In West Africa – Less virulent and not spread as widely and
rapidly as HIV 1
16. MORPHOLOGY
• It is roughly spherical
• diameter of about 120nm around 60times smaller than a red blood cell
• envelop enclosing two copies of positive single stranded RNA (Held
together by protein P7) enclosed by a conical capsid composed of viral
protein P24
• It is enclosed by a conical capsid composed of 2,000 copies of the viral
protein p24
• The RNA genome consists of 9 genes - Three of these genes: gag, pol, and
env, contain information needed to make the structural proteins for new virus
particles.
•
17. • Inside of capsid are three enzymes required for HIV replication: reverse
transcriptase, integrase and protease
• A matrix composed of the viral protein p17 surrounds the capsid ensuring
the integrity of the virion particle.
• This is, in turn, surrounded by the viral envelope, that is composed of
the lipid bilayer that contains a number of glycoproteins such as gp41
and gp120 these proteins bind to cell surface receptors during
infection.
18. RESISTANCE
• HIV doesn't survive well outside the body
• Temperature :
• HIV is thermo labile , being inactivated at 56C in 30 minutes and in
seconds at 100C.
• At room temperature it may survive up to seven days
• Disinfectants:
• It is inactivated in 10 minutes by treatment with 35% isopropyl alcohol,
70% ethanol, 0.5% sodium hypochlorite and 3% hydrogen peroxide.
19.
20. RESISTANCE
• For treatment of contaminated medical instruments a 2% glutaraldehyde
solution is useful
• Detergents:
• because of presence of lipid membrane therefore washing with
detergents is adequat for decontaminating clothes and household
utensils
• Lyophilisation:
• The virus withstand lyophilisation
21. RESISTANCE
• In dried blood it may survive for up to seven days
• At autopsy or necropsy , HIV has been isolated from various tissues
up to 16 days after dealth
22. MODES OF TRANSMISSION
• There are three modes of transmission:
• 1.sexual contact:
• Occurs among homosexual as well as heterosexual individuals
• HIV has been isolated from semen, vaginal and cervical secretions and breast
milk which are important vehicles of transmission
• Risk is also greatly enhanced if the sexual partners are more than one
• Parenteral transmission:
• Receiving infected blood transfusions, blood products
• Sharing contaminated syringes and needles
23. MODES OF TRANSMISSION
• Donated organs, tissue
• Perinatal transmission:
• Transmitted form an infected mother to her child either transplacentally
or perinatally
• During birth, infection may also develop from the genital secretions and
from mother milk after birth
27. EPIDEMIOLOGY
• Due to its large population size, India has the third largest HIV epidemic
in the world.
• Overall, India’s HIV epidemic is slowing down, with a 32% decline in new HIV
infections (80,000 in 2016), and a 54% decline in AIDS-related deaths
between 2007 and 2015.
• The three states with the highest HIV prevalence (Manipur, Mizoram,
Nagaland)
• 2.2% of female sex workers in India were living with HIV,
• 4.3% of men who have sex with men in India are living with HIV
28. EPIDEMOLOGY
• NACO estimates HIV prevalence among hijras to be 7.2%
• The number of people who inject drugs living with HIV in India is rising.
• 2.59% of the two million truckers in India are living with HIV.
• 40.5% of total HIV infections are among females.
29. PATHOGENEIS
• After entry into blood stream, HIV infect CD4 immune cells chiefly T helper lymphocytes. Other
cells like B-lymphocytes, monocytes, dendritic cells are also infected
• Glycoprotein GP120 present on surface has affinity for CD4 molecules present on surface of
immune cells.
• Co- receptor such as CXCR4 present on lymphocyte & CCR5 present on monocytes are also
needed for binding
• After fusion, HIV genome is uncouted and internalised into the cell
30. • Its genomic RNA is released in to cytoplasm & converted in to viral DNA (provirus) by
reverse transcriptase
• The viral DNA is integrated into host cells DNA by an enzyme integrase causing a latent
infection & captures the genetic machinery of host cells.
• This leads to rapid production of viral genome, which attains the shape of full virus with the
help of protease enzyme
• The new copies of HIV can now move on to infect other cells
31.
32.
33. IMMUNOLOGICAL ABNORMALITIES IN
HIV INFECTION
• Lymphopenia
• Selective T cell deficiency : reduction in number of T4 cells
• Hypergammaglobulinemia –predominantly IgG and IgA , IgM in children
• Decreased in vitro lymphocyte proliferative response to antigens
• Decreased cytotoxic response by T cells and NK cells
• Decreased antibody response to new antigens
• Altered monocyte/macrophage function
• Elevated levels of immune complexed in serum
34. In an infected person, HIV can be isolated from
blood, lymphocytes, cell-free plasma, cervical
secretions, semen, saliva, urine, tears and breast
milk
35. CLINICAL FEATURES
• Many people with HIV do not know they are infected. The clinical course of HIV
infection can present as follows:
• 1.Acute HIV infection:
• Withing 3-6 weeks of infection with HIV about 50% of persons experiene low
grade fever, malaise, headache,lymphadenopathy, rashes, swollen lymph
nodes, weight loss, fatigue, sweating, ulcers in the mouth, sour throat.
• HIV antibodies are usually negative at the onset of illness but become positive
during its course
• Hence this syndrome has been called sero conversion illness
36. ASYMPTOMATIC OR LATENT INFECTION
• After acute infection, the virus appears to become dormant, and the person feels
normal.
• This stage of HIV infection may last an average of eight to 10 years,
• During the latent period, the virus continues to multiply actively. It infects and kills
critical infection fighting cells, a type of white blood cell called CD4 cells or T
helper cells (T cells).
• Even though the person has no symptoms, he or she is contagious and can pass
HIV to others
• . At the end of this phase, the HIV viral load starts to rise, and the CD4 cell count
begins to drop.
38. AIDS-RELATED COMPLEX(ARS)
• When CD4+ T lymphocyte count falls below 400 per mm3, the patient may
develop symptoms
• live fever
• diarrhoea
• weight loss
• night sweats
• opportunistic infections like oral candidiasis, herpes zoster, hairy cell
leucoplakia, salmonellosis or tuberculosis
• ARC patients are usually severely ill and may of them progress to AIDS in a
few months
39. AIDS
• When CD4+ cells fall below 200 per mm3 the titre of viruses
increases markedly and there is irreversible breakdown of
immune defence mechanisms
• Most of the patients with HIV disease die of infections other
than HIV eg: opportunistic infections and malignancies
• AIDS is the end stage of HIV infection
40. OPPORTUNISTIC INFECTIONS AND
MALIGNANCIES TYPICALLY ASSOCIATED WITH
HIV INFECTION
• Parasites:
• Toxoplasmosis (fever, muscle pain)
• Cryptosporidiosis ( diarrheal disease)
• Isosporiasis ( intestinal disease)
• Mycotic:
• Pneumocystis jirovecii (pneumonia)
• Candidiasis
• Cryptococcosis (tumours in lungs)
• Aspergillosis
• Histoplasmosis (lungs)
41. OPPORTUNISTIC INFECTIONS AND
MALIGNANCIES TYPICALLY ASSOCIATED WITH
HIV INFECTION
• Bacteria:
• Tuberculosis
• Salmonellosis
• Legionellosis (penumonia)
• Malignancies:
• Kaposi sarcoma (cancer)
• Lymphomas(blood cancer)
42. AIDS
• A = not inherited
• I = immune system
• D = deficiency – inability to protect against illness
• S = syndrome, a group of symptoms or illnesses that occur as
a result of HIV infection
43. AIDS
• AIDS is not a virus but a set
of symptoms (or syndrome) caused by
the HIV virus.
• A person is said to have AIDS when their
immune system is too weak to fight off
infection,
• This is the last stage of HIV, when the
infection is very advanced, and if left
untreated will lead to death.
44. LABORATORY DIAGNOSIS
• specific tests for HIV infections
• 1.antigen detection : p24 antigen
• 2.virus isolation
• 3.detection of viral nucelic acid
• 4.antibody detection
• Non specific tests:
• 1.total and differential leucocyte
count
• 2.T lymphocyte subset assays
• 3. platelet count
• 4.IgG and IgA levels
• 5.skin tests for CMI(tuberculin test)
• Tests for opportunistic infections and
tumour
45. LABORATORY TESTS FOR DETECTION OF
SPECIFIC ANTIBODIES IN HIV INFECTION
• Screening tests:
1.ELISA
• 2.rapid tests
A. dot blot assay
B. lateral flow
assay(immunochromatography)
C. particle agglutination
D. HIV spot and comb tests
• 2.supplemental test
a. western blot test
B. indirect immunofluorescence
test
C. radio immuno precipitation
assay
46.
47. NON SPECIFIC TESTS
• Total and differential leucocyte count:
• In AIDS there is leucopenia with a lymphocyte count less than 200 per mm3
• T lymphocyte subset assays:
• The normal CD4 : CD8 T cell ratio of 2:1 is reversed to 0.5: 1 in cases of AIDS
• Platelet count:
• There is thrombocytopenia in patients of AIDS
• IgG and IgA levels:
• Both levels are raised in blood
48.
49. PREVENTION
• Health education
• Indiscriminate sex
• Use of condoms
• Avoid sharing razors, needles and tooth brushes
• Comprehensive sex education programmers in school.
• Public awareness campaigns for HIV.
50. • All mass media channels should be involved in educatingt he people on AIDS,
its nature of transmission & prevention.
• Prevention of blood borne HIV transmission
• People with high risk should not donate blood,body organs, sperm or other
tissues.
• All blood should be screened before transfusion
• Strict sterilization practice in hospitals and clinics
• Disposable needles and syringes should be used.
• Universal precautions by health care workers.
51. PROPHYLAXIS
• No effective vaccine has yet been found out
• High rate of mutation, diverse antigenic types and subtypes, long latency
and persistence in infected cells as provirus posses serious problems in
the development of vaccine
• Several stratgies have been explored for vaccine preparation
• 1.modified whole virus
• 2.subunits based on envelope glycoproteins
• 3.target cell protection by anti CD4 antibody
52. ANTIRETROVIRAL THERAPY
• It will not cure the disease but can prolong the life of severely ill patients
• Antiretroviral drugs include both nucleoside and non nucleoside inhibitors
of enzyme revere transcriptase, viral protease inhibitors, fusion
inhibitors,integrase inhibitor and entry inhibitor
53.
54.
55. POSTEXPOSURE PROPHYLAXIS(PEP)
• It refers to anti retroviral drug therapy with in hrs. Following accidental exposure to
virus.
• Following needle stick injury, the part should be thoroughly washed with soap&
water. The injured finger should not be reflex to put in the mouth.
• Open wounds should be irrigated with saline.
• Following treatment is recommended by the US center for disease control and
prevention for health care workers accidentally exposed to HIV: -• zidovudine(
200mg three times daily) +Lamivudine (150 mg twice daily) for4 weeks
56. POSTEXPOSURE PROPHYLAXIS(PEP)
• If “ source individual have advance aids : Nelfinavir(750 mg 3 times
daily)+zidovudine +lamivudine
• if “ source” individual failed on zidovudine +lamivudine therapy then
stavudine +didanosine
57. PREVENTION OF INFECTION TO BABY BY
HIV POSITIVE MOTHER
• -a) zidovudine( 300mg three times daily) –to pregnant mothers from 10-
12th week of pregnancy or immediately after diagnosis.
• b) During labour- zidovudine
• c) New born -Syrup zidovudine( three times daily for 6 weeks)
• d) Single dose of Neverpin (200 mg) at the time of labour.
58.
59.
60. “Prevention is better than cure
Especially when something has
NO CURE “
Stop HIV/ AIDS
THANK YOU
