Background
In May 2022, WHO considered the outbreak of mpox infection as a public health emergency of international concern (PHEIC). Vaccination was recommended for people living with HIV (PWH) and users of pre-exposure prophylaxis (PrEP). The need to vaccinate the population at risk worldwide, mainly PWH and PrEP users has increased. The immune response generated after infection was analyzed in comparison with vaccinated individuals.
Methods
We recruited mpox-infected persons (mpox+)(n=31), mpox-vaccinated persons (n=13;n=11 one and two doses) and persons who were not in contact with mpox and smallpox (non-exposed)(n=38). Mpox peptides were used to stimulate CD4+ and CD8+ T cells and the expression of different markers and cytokines was analyzed by flow cytometry.
Results
1)The mpox+ participants were infected a median of 258(IQR 254-285) days ago; those vaccinated with one dose a median of 339 days ago(IQR 288-349) and those who received two doses 126(IQR 72-169) days ago. The median age of the groups was 37(IQR 34-47), 34(IQR 32-40), 38(IQR 35-41) and 34(IQR 27-46) years respectively. All participants were male. There were 25 PWH mpox+(80.6%), 4 PWH vaccinated(32.2%) and 11 PWH in the non-exposed group (28.9%). 2)CD4+ T-cell stimulation induced a 1.5(p=0.0128) and 1.3(p=0.0486) fold decrease in lymphocyte levels in the mpox+ group compared to single dose vaccinated and non-exposed group. CD4 lymphocytes expressed 1.8(p=0.0439) times higher levels of IL-2 in mpox+ individuals compared to those vaccinated with two doses. 3)Naive CD4+ T cells in the mpox+ group expressed higher levels of CD25+ marker (1.5-fold;p=0.0155) compared to the non-exposed group and of IFNγ (2.5-fold; p=0.0265) compared to those vaccinated with two doses. 4)Central memory CD4+ CD4+ T cells were increased 3.1 (p=0.0118) and 2-fold (p=0.0183) more in mpox+ individuals compared to those vaccinated with two doses and the non-exposed group, respectively. 5)CD8+ T cells expressed 1.6 (p=0.0321) and 2.1 (p=0.0084) times more IFNγ and TNFα than those vaccinated with one dose respectively. 6)No difference was found between the response of HIV-infected and PrEP users.
Conclusions
People infected with mpox showed a potent and long-lasting immune response to mpox peptides. Vaccination against mpox did not produce significant changes in the capacity to response to mpox peptides compared to those not previously exposed to the virus.
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