Alb-PSX transgenic line 107-5D mice (also called Tg[Alb-1,HBV]Bri66; inbred B10D2, H-2d) have the mouse albumin promoter sequences directing expression of the envelope/surface antigen coding region (HBsAg) of the hepatitis B virus (HBV). This results in retention of the non-secretable filamentous HBsAg particle in the hepatocyte endoplasmic reticulum; with little-to-no HBsAg secretion into serum. These mice are a model for studying the immunopathogenesis of acute T cell mediated hepatitis, chronic T cell mediated hepatitis, and the downstream consequences of chronic hepatitis, especially hepatocellular carcinoma.
Dr. Francis (Frank) V Chisari, The Scripps Research Institute
Alb-PSX transgenic line 107-5D mice (also called Tg[Alb-1,HBV]Bri66; inbred B10D2, H-2d) express nontoxic quantities of the three hepatitis B virus envelope/surface antigen proteins (large, middle, and small; all containing hepatitis B surface antigen (HBsAg) determinants) in their hepatocytes, are immunologically tolerant to HBsAg at the T cell level, and display no evidence of spontaneous liver disease nor hepatocellular carcinoma during their lifetime.
During the normal HBV replication cycle, the middle and small envelope proteins assemble to form the HBV major envelope polypeptide (a 22 nm spherical subviral particle containing HBsAg) that is rapidly-secreted secreted by the hepatocyte into the circulation. However, the ability of the hepatocytes to secrete these HBsAg subviral particles is inversely proportional to the abundance of the large envelope protein which, when coexpressed with the middle and small envelope proteins, forms long non-secretable filamentous particles that accumulate in the endoplasmic reticulum (where they are readily detectable immunohistochemically), thus precluding secretion of the 22 nm spherical forms.
The Alb-PSX transgene is designed to have the mouse albumin promoter sequences directing expression of the HBV large envelope protein, but expression of the middle and small envelope proteins are regulated by a constitutively active internal promoter located within the envelope coding region on the transgene. Therefore, the albumin-promoter driven hepatocellular expression of the large envelope polypeptide results in the formation and retention of the non-secretable filamentous HBsAg particle in the hepatocyte endoplasmic reticulum (where it is detectable principally as cytoplasmic HBsAg in periportal hepatocytes close to the point of entry of the circulation into the hepatic lobule) and gives the hepatocytes a "ground glass" appearance. This renders the hepatocytes highly susceptible to destruction (MHC class I-restricted necro-inflammatory liver disease) after immune system ablation with subsequent adoptive transfer of HBsAg-specific cytotoxic T lymphocytes (CTLs).
Alb-PSX transgenic line 107-5D mice exhibit no detectable liver expression (RNA or protein) from the transgenic HBV X gene.
Hemizygous mice are viable, fertile and healthy. To date (July 2015), it has not been attempted to make this strain homozygous.
Importantly, the donating investigator confirms that the Alb-PSX transgenic line 107-5D mice do not produce the infectious HBV particle (hepatitis B virion aka Dane particle). This is because the Alb-PSX transgene does not have the sequences encoding the viral DNA polymerase (P gene) or the HBV core protein (pre-C [HBeAg] and C gene [HBcAg]).
The Alb-PSX transgene was designed by Dr. Francis V. Chisari (The Scripps Research Institute) in collaboration with Dr. Ralph L. Brinster (University of Pennsylvania) and Dr. Richard D. Palmiter (University of Washington). This Alb-PSX transgene has the mouse albumin promoter sequences upstream of the hepatitis B virus HBsAg coding region (PSX). Specific details are below.
The mouse albumin promoter sequences were contained within a 12 kbp fragment that also contains tissue specific enhancers. The 14.3 kbp transgene was microinjected into the male pronucleus of cells from B10.D2 (from The Jackson Laboratory). Founder animals were bred to the same B10.D2 strain; producing eight Alb-PSX lineages. The donating investigator reports that mice from lineage 107-5D were maintained by breeding with the same B10.D2 strain each generation for 20 generations. These Alb-PSX transgenic line 107-5D mice (also called Tg[Alb-1,HBV]Bri66; inbred B10D2, H-2d) were used to freeze sperm by Dr. Chisari. Some of that frozen sperm was sent to The Jackson Laboratory Repository in 2015. Upon arrival, the frozen sperm was used to fertilize oocytes from the C5-functional B10.D2 strain (Stock No. 000463; B10.D2-Hc1 H2d H2-T18c/nSnJ).
In 2015, the first generation rederived mice at The Jackson Laboratory were all found to be H-2Kd and to also have C57BL/6 allele-type for other specific markers (CD45.2 and Thy1.2).
Of note, the donating investigator reports that, at least once during backcrossing, a hemizygous female was bred to a B10.D2 male (thus the Y chromosome of the congenic strain is of C57BL/10 origin).
The HBsAg coding region (PSX) is the 2.3 kbp BglII A fragment from the hepatitis B virus (HBV; subtype ayw) genome spanning nucleotides 2839 and 1986 (from GenBank V01460.1). This region contained the entire HBV envelope/surface antigen (HBsAg) open reading frame (pre-S1, pre-S1 and S), the region between the S and X genes, and the X gene.
The HBsAg coding region consists of three translation initiation codons at nucleotides 2850, 3174, and 157 (which represent, respectively, the N termini of the large, middle, and major envelope polypeptides), and a stop codon at nucleotide 835. Additionally, transcriptional start sites in the vicinity of nucleotide 1/3182 and mRNA polyadenylation recognition sequence starting at nucleotide 1918 define the approximate termini of the HBV transcript which encodes the major envelope polypeptide.
The Alb-PSX transgene is constructed such that the HBV large envelope protein can be produced only from a larger transcript emanating from the transcription start sites defined by the mouse albumin promoter, but the middle and small envelope proteins are regulated by a constitutively active internal promoter located within the envelope coding region.
|Expressed Gene||HBV, hepatitis B virus large envelope polypeptide,|
|Site of Expression|
|Allele Name||d variant|
|Gene Symbol and Name||H2, histocompatibility-2, MHC|
|Strain of Origin||various|
|General Note||The d variant has been observed in the following strains: DBA/2, DBA/2J BALB/c, BALB/cByJ, BALB/cJ, C57BLKS, NZB.|
|Allele Name||transgene insertion 66, Ralph L Brinster|
|Allele Type||Transgenic (Inserted expressed sequence)|
|Allele Synonym(s)||107-5D; Alb-PSX; HBsAg; Tg[Alb-1,HBV]Bri66|
|Gene Symbol and Name||Tg(Alb1-HBV)66Bri, transgene insertion 66, Ralph L Brinster|
|Promoter||Alb1, Albumin , Mouse|
|Expressed Gene||HBV, hepatitis B virus large envelope polypeptide,|
|Strain of Origin||C57BL/10 x DBA/2|
|Molecular Note||A BglIIA fragment of HBV subtype ayw spanning nucleotides 239-1986 encoding the entire HBV envelope coding region was placed under the constitutive transcriptional control of the mouse albumin promoter.|
When maintaining a live colony, hemizygous mice may be bred to wildtype (noncarrier) siblings, or to the B10.D2 strain (Stock No. 000463). To date (July 2015), it has not been attempted to make this strain homozygous.
When using the Alb-PSX transgenic line 107-5D mouse strain in a publication, please cite the originating article(s) and include JAX stock #027528 in your Materials and Methods section.