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An introduction to Herpesviridae

AN INTRODUCTION TO
HERPESVIRIDAE
WHAT ARE THEY AND HOW IS THEIR BEHAVIOR ?
DR. KAVEH HARATIAN

BASICS ABOUT HERPESVIRUSES
• FAMILY : HERPESVIRIDAE
• SUBFAMILY : ALPHA, BETA, GAMMA HERPESVIRINAE (LYMPHOCRYPTO- , RHADINO- )
• SIZE : 120 – 300 NM
• CAPSID SYMMETRY : ICOSAHEDRAL (100 NM , 160 CAPSOMERS)
• ENVELOPE : YES
• GENOME : LINEAR DSDNA
• GENOME REPLICATED : NUCLEUS
• VIRUS ASSEMBLY : NUCLEUS
• COMMON FEATURES : PRIMARY INFECTIONS USUALLY INAPPARENT IN CHILDHOOD .
LATENT/RECURRENT INFECTIONS .

KEY PROPERTIES OF HERPESVIRUSES

LATENCY
• THE VIRUS SHOULD SUCCESSFULLY EVADE THE HOST IMMUNE RESPONSE
• MUST BE ABLE TO INSERT ITS GENOME INTO HOST CELL
• GENOME PERSIST IN THE LATENTLY INFECTIOUS CELLS
• EASY FOR NEUROTROPIC HERPESVIRUSES (ALPHAVIRUSES) : INFECT NON-DIVIDING CELLS :
NEURONS
• MORE DIFFICULT FOR LYMPHOTROPIC HERPESVIRUSES( (GAMMAVIRUSES) : INFECT DIVIDING
AND MITOTIC CELLS : B CELLS

VIRUS TRANSMISSION
• CLOSE CONTACT :
• SEXUAL CONTACT
• SKIN, GENITALIA OR EYE CONTACT WITH VIRUS FROM HERPETIC
LESIONS

PATHOGENICITY
• INCUBATION PERIOD : 2 – 12 D (MOST CASES : 4 D)
• INFECTIOUS PERIOD : FROM ONSET OF CLINICAL SYMPTOMS TO COMPLETE
REMOVAL.
• AT-RISK PEOPLE : ALL INFANTS AND ADULTS WITH IMMUNOCOMPROMIZED
IMMUNITY.

REPLICATION OF HERPESVIRUSES
•‫میزبان‬ ‫سلول‬ ‫به‬ ‫ویروس‬ ‫اتصال‬:‫گلیکوپروتئین‬ ‫توسط‬C
•‫پالسمایی‬ ‫غشاء‬ ‫با‬ ‫ویروس‬ ‫انولوپ‬ ‫ادغام‬:‫های‬ ‫گلیکوپروتئین‬B, D, H
•‫سیتوپالسم‬ ‫به‬ ‫تگومنت‬ ‫و‬ ‫کپسید‬ ‫ورود‬...‫هسته‬ ‫به‬ ‫شدن‬ ‫نزدیک‬...‫ورود‬DNA‫هسته‬ ‫به‬ ‫ویروس‬ ‫خطی‬
•‫انجام‬ ‫هسته‬ ‫در‬ ‫ویروس‬ ‫اسمبلی‬ ‫و‬ ‫همانندسازی‬ ، ‫رونویسی‬ ‫های‬ ‫پدیده‬ ‫اغلب‬‫گیرد‬ ‫می‬.
•‫آلفا‬ ‫های‬ ‫ژن‬:MRNA‫آلفا‬:‫ویروسی‬ ‫بسیارزودرس‬ ‫های‬ ‫پروتئین‬.....‫بتا‬ ‫های‬ ‫ژن‬ ‫شدن‬ ‫فعال‬:MRNA‫بتا‬:‫و‬ ‫زودرس‬ ‫های‬ ‫پروتئین‬
‫همانندسازی‬ ‫برای‬ ‫که‬ ‫ویروس‬ ‫آنزیمی‬DNA‫هستند‬ ‫ضروری‬.... .‫گاما‬ ‫های‬ ‫ژن‬ ‫شدن‬ ‫فعال‬:MRNA‫گاما‬:‫ساختمانی‬ ‫های‬ ‫پروتئین‬
‫ویروس‬.
•‫جوانه‬‫دهد‬ ‫می‬ ‫رخ‬ ‫هسته‬ ‫غشاء‬ ‫خالل‬ ‫از‬ ‫زدن‬.
•‫گردد‬ ‫می‬ ‫منجر‬ ‫میزبان‬ ‫سلول‬ ‫انهدام‬ ‫به‬ ‫همانندسازی‬ ‫فرایند‬.

CLINICAL SYMPTOMS
• PRIMARY/RECURRENT SKIN INFECTION .
• ORAL/LABIAL INFECTION … ACUTE HERPETIC GINGIVOSTOMATITIS.
• GENITAL INFECTION.
• HERPETIC ENCEPHALITIS.
• MENINGITIS
• KERATOCONJUNCTIVITIS
• PNEUMONIA
• NEONATAL HERPES INFECTION (GENERALIZED)

DIAGNOSIS METHODS
• CELL CULTURE
• PCR
• IFA

TREATMENT AND IMMUNIZATION
• ACYCLOVIR
• IMMUNOCOMPROMIZED PATIENTS SHOULD BE TAKE UNDER PROPHYLAXIS REGIMEN.
• FOSCARNET
• ADEFOVIR

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An introduction to Herpesviridae

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