Viral latency

Viral latency is the ability of a virus to remain dormant within the host cell, sometimes establishing lifelong occult infection. Depending on the virus, the trigger of latency is highly variable but the host cell context is always determining. Latency can stop upon viral genome reactivation, often promoted by stress cellular signals.

The viral genome can remain latent either as an episome or integrated in the host chromosome. The latter allows replication of the viral genome during host cell division. Virus latency is generally maintained by a few viral genes that keep the viral genome silent and escape from host immune system.

Eukaryotic viruses like some herpesviridae or retroviridae are able to infect their host lifelong thanks to latency. This gives them an enormous advantage for disseminating in their host population: about 90% of human population would be infected with varicella-zoster virus.
Virus Family Genus Latent replication form Main site of latency Ref.
HHV-1,
HHV-2
Herpesviridae Simplexvirus Circular episome Dorsal root ganglia
HHV-3 Herpesviridae Varicellovirus Circular episome Dorsal root ganglia
HHV-4 Herpesviridae Lymphocryptovirus Circular episome Memory B-cells
HHV-5 Herpesviridae Cytomegalovirus Circular episome Myeloid progenitor cells
HHV-6 Herpesviridae Roseolovirus Probable telomeric integration Monocytes (HHV-6B)
HHV-7 Herpesviridae Roseolovirus Circular episome CD4+ T-cells
HHV-8 Herpesviridae Rhadinovirus Circular episome B-cells
HIV-1 Retroviridae Lentivirus Provirus Memory T-cells
HTLV-1 Retroviridae Deltaretrovirus Provirus Memory T-cells



Prokaryotic viruses which display a latent phase are called “temperate”, or “lysogenic”. The term lysogenic refers to a host phenotype: the bacteria can be spontaneously lysed by the latent phage.
Bacteria such as E. coli and Salmonella contain multiple resident proviruses whose variability in number and type constitutes a major source of diversity between strains . Prokaryotic proviruses usually carry cargo genes encoding traits adaptive to the host, among which are virulence factors found in many bacterial pathogens.

Viruses that have the ability to lie latent within a cell have two options when infecting a cell: they can either enter the latency or the lytic pathway. The decision between lytic and latent pathways is regulated by expression of regulatory proteins part of a genetic switch system, usually repressor(s) as well as proteins controlling the stability of the later. The outcome of the followed pathways depends on the ratio of these key regulators. This ratio may be determined by environmental factors such as the host cell type, its shape, or the nutriment availability.
A well known genetic switch system is the one of bacteriophage lambda which includes at least a repressor of the lytic promoter, a repressor of the latency promotor and two key regulators .

Matching UniProtKB/Swiss-Prot entries

47 entries grouped by protein (browse by keywords)

All proteins are shown (view only 37 complete proteome entries)

1 entry

Trans-activator protein BZLF1 (EB1) (Zebra)

BZLF1_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain

3 entries

Epstein-Barr nuclear antigen 1 (EBNA-1) (EBV nuclear antigen 1)

Select_allDeselect_all
EBNA1_EBVA8
Epstein-Barr virus (strain AG876) (HHV-4) (Human herpesvirus 4) reference strain
EBNA1_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain
EBNA1_EBVG
Epstein-Barr virus (strain GD1) (HHV-4) (Human herpesvirus 4) reference strain

3 entries

Epstein-Barr nuclear antigen 6 (EBNA-6) (EBV nuclear antigen 6) (Epstein-Barr nuclear antigen 3C) (EBNA-3C) (EBV nuclear antigen 3C) (Epstein-Barr nuclear antigen 4B) (EBNA-4B) (EBV nuclear antigen 4B)

Select_allDeselect_all
EBNA6_EBVA8
Epstein-Barr virus (strain AG876) (HHV-4) (Human herpesvirus 4) reference strain
EBNA6_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain
EBNA6_EBVG
Epstein-Barr virus (strain GD1) (HHV-4) (Human herpesvirus 4) reference strain

2 entries

E3 ubiquitin-protein ligase ICP0 (EC 2.3.2.27) (Alpha-0 protein) (Immediate-early protein IE110) (RING-type E3 ubiquitin transferase ICP0) (Trans-acting transcriptional protein ICP0) (VMW110)

Select_allDeselect_all
ICP0_HHV11
Human herpesvirus 1 (strain 17) (HHV-1) (Human herpes simplex virus 1) reference strain
ICP0_SUHVF
Suid herpesvirus 1 (strain Indiana-Funkhauser / Becker) (SuHV-1) (Pseudorabies virus (strain Indiana-Funkhauser / Becker))

E3 ubiquitin-protein ligase ICP0 (EC 2.3.2.27) (Early protein 0) (EP0) (RING-type E3 ubiquitin transferase ICP0)

1 entry

Protein ORF49

ORF49_HHV8P
Human herpesvirus 8 type P (isolate GK18) (HHV-8) (Kaposi's sarcoma-associated herpesvirus) reference strain

1 entry

Regulatory protein cro

RCRO_LAMBD
Escherichia phage lambda (Bacteriophage lambda) reference strain

1 entry

Repressor protein c (Repc) (CI) (Gene product 1) (gp1) (Mu repressor) (MuR)

REPC_BPMU
Escherichia phage Mu (Bacteriophage Mu) reference strain

14 entries

Ribonucleoside-diphosphate reductase large subunit (R1) (EC 1.17.4.1) (Ribonucleotide reductase large subunit)

Select_allDeselect_all
RIR1_ALHV1
Alcelaphine herpesvirus 1 (strain C500) (AlHV-1) (Malignant catarrhal fever virus) reference strain
RIR1_EBVA8
Epstein-Barr virus (strain AG876) (HHV-4) (Human herpesvirus 4) reference strain
RIR1_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain
RIR1_EBVG
Epstein-Barr virus (strain GD1) (HHV-4) (Human herpesvirus 4) reference strain
RIR1_EHV1B
Equine herpesvirus 1 (strain Ab4p) (EHV-1) (Equine abortion virus) reference strain
RIR1_HHV11
Human herpesvirus 1 (strain 17) (HHV-1) (Human herpes simplex virus 1) reference strain
RIR1_HHV2H
Human herpesvirus 2 (strain HG52) (HHV-2) (Human herpes simplex virus 2) reference strain
RIR1_PSHV1
Psittacid herpesvirus 1 (isolate Amazon parrot/-/97-0001/1997) (PsHV-1) (Pacheco's disease virus) reference strain
RIR1_VZVD
Varicella-zoster virus (strain Dumas) (HHV-3) (Human herpesvirus 3) reference strain
RIR1_BHV1C
Bovine herpesvirus 1.1 (strain Cooper) (BoHV-1) (Infectious bovine rhinotracheitis virus)
RIR1_EHV4
Equine herpesvirus 4 (strain 1942) (EHV-4) (Equine rhinopneumonitis virus)
RIR1_HHV23
Human herpesvirus 2 (strain 333) (HHV-2) (Human herpes simplex virus 2)
RIR1_SUHVK
Suid herpesvirus 1 (strain Kaplan) (SuHV-1) (Pseudorabies virus (strain Kaplan))
RIR1_VZVO
Varicella-zoster virus (strain Oka vaccine) (HHV-3) (Human herpesvirus 3)

15 entries

Ribonucleoside-diphosphate reductase small subunit (EC 1.17.4.1) (Ribonucleotide reductase small subunit)

Select_allDeselect_all
RIR2_ALHV1
Alcelaphine herpesvirus 1 (strain C500) (AlHV-1) (Malignant catarrhal fever virus) reference strain
RIR2_EBVA8
Epstein-Barr virus (strain AG876) (HHV-4) (Human herpesvirus 4) reference strain
RIR2_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain
RIR2_EBVG
Epstein-Barr virus (strain GD1) (HHV-4) (Human herpesvirus 4) reference strain
RIR2_EHV1B
Equine herpesvirus 1 (strain Ab4p) (EHV-1) (Equine abortion virus) reference strain
RIR2_HHV11
Human herpesvirus 1 (strain 17) (HHV-1) (Human herpes simplex virus 1) reference strain
RIR2_HHV2H
Human herpesvirus 2 (strain HG52) (HHV-2) (Human herpes simplex virus 2) reference strain
RIR2_PSHV1
Psittacid herpesvirus 1 (isolate Amazon parrot/-/97-0001/1997) (PsHV-1) (Pacheco's disease virus) reference strain
RIR2_VZVD
Varicella-zoster virus (strain Dumas) (HHV-3) (Human herpesvirus 3) reference strain
RIR2_BHV1C
Bovine herpesvirus 1.1 (strain Cooper) (BoHV-1) (Infectious bovine rhinotracheitis virus)
RIR2_EHV4
Equine herpesvirus 4 (strain 1942) (EHV-4) (Equine rhinopneumonitis virus)
RIR2_HHV1K
Human herpesvirus 1 (strain KOS) (HHV-1) (Human herpes simplex virus 1)
RIR2_HHV23
Human herpesvirus 2 (strain 333) (HHV-2) (Human herpes simplex virus 2)
RIR2_SUHVK
Suid herpesvirus 1 (strain Kaplan) (SuHV-1) (Pseudorabies virus (strain Kaplan))
RIR2_VZVO
Varicella-zoster virus (strain Oka vaccine) (HHV-3) (Human herpesvirus 3)

1 entry

Repressor protein cI

RPC1_LAMBD
Escherichia phage lambda (Bacteriophage lambda) reference strain

1 entry

Transcriptional activator II

RPC2_LAMBD
Escherichia phage lambda (Bacteriophage lambda) reference strain

1 entry

Protease inhibitor III

RPC3_LAMBD
Escherichia phage lambda (Bacteriophage lambda) reference strain

3 entries

Replication and transcription activator (Rta) (Immediate-early protein Rta)

Select_allDeselect_all
RTA_EBVA8
Epstein-Barr virus (strain AG876) (HHV-4) (Human herpesvirus 4) reference strain
RTA_EBVB9
Epstein-Barr virus (strain B95-8) (HHV-4) (Human herpesvirus 4) reference strain
RTA_EBVG
Epstein-Barr virus (strain GD1) (HHV-4) (Human herpesvirus 4) reference strain