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21-05-20, 10:51 PM
Hep B (HBV)
A. First marker that comes up is surface Ag (HBsAg). It comes up about 1 month after you have the infection. You don’t know you have it and are asymptomatic. The enzyme studies are normal. The next thing that comes up is the bad guys: E Ag (HBeAg) and HBV DNA, b/c these are only ones that are infective. Then the first Ab comes up a lil after the DNA and E Ag, which is core Ab IgM (Anti-HBc) (this is expected b/c the first Ab against acute inflammation is IgM). The majority of people with Hep B recover (about 90%); those with HIV+ never recover and will have chronic cases b/c they have no immune response to knock it off. If you do recover the first things to go away are E Ag (HBeAg) and HBV DNA. The last of the Ag’s that goes away is surface Ag (HBsAg). So, surface Ag is the first to come and the last to leave (like a “house within a house” – look at the chart and will see that S Ag is the big house and E Ag and HBV DNA are the lil houses under big house). In other words, it is IMPOSSIBLE to be E Ag positive and S Ag negative (E Ag and DNA come up after S Ag and leave before).

Surface Ab doesn’t come up until about 1 month after S Ag is gone, so there is this gap, which is a ‘window’ with nothing elevated (only has one Ab there; S Ag, E Ag, HBV DNA are all gone, and S Ab not there yet). So, how do you know the pt HAD Hep B? Core IgM doesn’t leave – it stays there and becomes IgG over time. So, the marker for that window period when all the bad guys are gone and surface Ab hasn’t arrived yet, is core Ab IgM (which tells you that you HAD Hep B and are in the process of recovery). There is no way you are infected during this period – why? B/c E Ag and HBV DNA are not there. Therefore, you are not infective – it just means that you HAD Hep B and are in the process of recovering. YOU ARE NOT INFECTIVE – this is between the 5th and 6th month.

So, if you had Hep B, there should be 2 Ab’s that you have: core Ab IgG and surface Ab IgG.

If you have been vaccinated, cannot have anything b/c you had yeast make surface Ag, which is what the vaccine consists of. The only bad Ab you can get from injecting surface Ag is Ab’s against it. So, only Ab you will have if you were vaccinated is Surface Ab. NOT core Ab IgG b/c were not injected with that. Core Ab is not a protective Ab.

B. Chronic hepatitis is a definition: “How long have you had surface Ag?” If it’s more than 6 months, you have chronic Hep B. So, are you infective or not? – are you an infective carrier or healthy carrier? You automatically know if you are an infective chronic carrier if you have HBV DNA. This means that you are a patient with chronic Hep B that is infective. So, you’re a walking hazard, and your intimate contacts need to be immunized b/c the dz can be transmitted sexually to those people, or by IV (IVDA’s). If you are negative for E Ag and HBV DNA but are surface Ag positive, then it makes you a “healthy” carrier (this does not mean you are healthy – you are still a chronic carrier of Hep B). If you are a healthy carrier, however, the chances of recovery are excellent b/c in about one year, S Ag will disappear and S Ab will come up. Will also have core Ab IgG at this time – this means that you have a good chance of total recovery. Also have a good chance of recovery with E Ag b/c pt is a candidate for Alpha IFN therapy (DOC). Never give corticosteroids to any chronic viral infections.

C. Review:
What we expect in acute hepatitis B (what would the markers be)? S Ag, E Ag, HBV DNA, and core IgM What if the pt is in the window period? Core IgM
What if had Hep B, but have recovered from it? Core Ab IgG and surface Ab IgG
What if pt was vaccinated (what is the ONLY thing you should have)? Surface Ab IgG
What if you have at the end of 6 months S Ag, core IgM, with everything else neg? Healthy carrier What if you have after 6 months surface Ag, E Ag, HBV DNA and core Ab IgM? Infective carrier.

21-05-20, 11:32 PM
Thuật ngữ:
HBsAg: Hepatitis B surface Antigen - Kháng nguyên bề mặt.
HBcAg: Hepatitis B core Antigen - Kháng nguyên lõi
HBeAg: Hepatitis B envelop Antigen - Kháng nguyên nội sinh
Surface Ab (HBsAb): Kháng thể kháng kháng nguyên bề mặt
Core IgM: Kháng thể kháng lõi -> xuất hiện trong giai đoạn cấp tính.
Core IgG: Kháng thể kháng lõi trong giai đoạn mạn tính

- Khoảng 1 tháng sau khi bị nhiễm viêm gan B thì lần lượt các kháng nguyên của nó sẽ xuất hiện theo thứ tự HBsAg -> HBeAg, HBV DNA. Và trong giai đoạn hồi phục thì chúng mất đi theo thứ tự ngược lại.
- Kháng thể xuất hiện đầu tiên trong giai đoạn cấp là Core IgM, xuất hiện ngay sau HBeAg và HBV DNA. Còn kháng thể Surface Ab chỉ xuất hiện sau khi HBsAg biến mất khoảng 1 tháng. Vậy trong 1 tháng đó khi HBsAg, HBeAg, HBV DNA biến mất, chưa có Surface Ab, người ta gọi là giai đoạn cửa sổ (window period). Vậy làm sao để biết là ta đã bị nhiễm HBV?. Đó là nhờ vào anh Core IgM xuất hiện trước đó trong giai đoạn cấp và cho biết chúng ta đang trong giai đoạn hồi phục.
- Tiêm ngừa vaccine chỉ giúp ta tạo được Surface Ab mà thôi, không tạo được Core IgM.
- Viêm gan B mạn tính khi nào? Khi kháng nguyên bề mặt HBsAg xuất hiện trên 6 tháng.
- Bạn bị nhiễm HBV khi có HBV DNA (+).
- Còn nếu HBeAg (-), HBV DNA (-) và HBsAg (+) thì bạn là người lành mang trùng.

Theo giai đoạn:
- Nhiễm HBV cấp tính: Phải có HBsAg, HBeAg, HBV DNA và Core IgM
- Giai đoạn cửa sổ: HBsAg, HBeAg, HBV DNA đều (-), chỉ có Core IgM
- Đã nhiễm và đang hồi phục: HBeAg (-), HBV DNA (-), có Core IgG, Surface IgG
- Tiêm ngừa: Surface Ab IgG
- Người lành mang trùng: HBsAg (+), Core IgM
- Bị nhiễm: Sau 6 tháng có HBsAg, HBeAg, HBV DNA và Core IgM.