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Study: Smallpox vaccine efficiently induces immunity against mpox virus infection in people living with HIV

Smallpox vaccine efficiently induces immunity against monkeypox virus infection in people living with HIV
Comparison of subcutaneous (s.c.) and intradermal (i.d.) JYNNEOS vaccination routes. Pan-pox-specific interferon-γ (IFN-γ) enzyme-linked immunospot (ELISpot) (A), Th1 CD4+ (B), and Th1 CD8+ (C) T-cell responses after i.d. or s.c. JYNNEOS vaccination of human immunodeficiency virus-1 (HIV-1) hiCD4 group individuals. Pan-pox-specific α4β7+ CD4+ (D) or CD8+ (E) T-cell responses for HC and HIV-1-infected individuals after s.c. or i.d. JYNNEOS vaccination. Given are the differences in percentages to the prevaccination time point. Individual values for IFN-γ ELISpots and intracellular cytokine staining (ICS) assays are shown. Statistically significant differences between the groups were calculated using a one-way analysis of variance test for parametric data or a Kruskal–Wallis test for nonparametric data. Nonsignificant differences were indicated as “ns” and differences with p values < 0.05 were considered significant and were indicated with asterisks: *p < 0.05; **p < 0.01; ***p < 0.001. Donut charts under figures A–E show the number “n” of individuals analyzed and percentages of responders (gray-colored in chart) and nonresponders (white-colored in chart). Credit: Journal of Medical Virology (2023). DOI: 10.1002/jmv.29317

Researchers from the Infection Biology Lab at the Department of Medicine and Life Sciences (MELIS) at Pompeu Fabra University and the HIV Unit at Hospital del Mar Research Institute have shown that intradermal vaccination with the JYNNEOS vaccine against smallpox is the best option to protect people living with HIV from contracting the monkeypox virus.

This route of administration requires less material to inject each patient, extending the available vaccine doses by a factor of five. The results of this observational study also indicate that individuals with a low level of CD4 T cells, a type of white blood cell essential to properly fight new infections, need a booster dose 28 days after the first dose to compensate for their immunosuppressed status.

Monkeypox (mpox) is a zoonotic virus of the variola virus family that causes smallpox. Mpox causes an infectious disease that can spread autochthonously between humans through direct contact and respiratory routes. The most common symptoms of infection are fever, headache, muscle pain, swollen lymph nodes, rash, respiratory and rectal symptoms, and exhaustion. Its severity depends on age and the response of the immune system to resist pathogens and parasites.

Prior to the spring of 2022, monkeypox used to appear in the form of single outbreaks in endemic areas of Central and West Africa, but at this time a global outbreak occurred that facilitated human-to-human transmission. Transmission was mainly between men who had sex with men, a population group with many HIV-infected individuals, who are particularly susceptible to infection and pathogenicity.

Although there is no specific vaccine against monkeypox, the smallpox vaccine protects eight out of ten people from monkeypox infection due to the antigenic relatedness between the two viruses.

Fighting monkeypox while living with HIV

Results of the study published in the Journal of Medical Virology indicate that the activity of T cells, responsible for the response against pathogens, homeostasis and the system's memory, in HIV-1-infected individuals, whose viral load was controlled by , was enhanced after vaccination with the JYNNEOS . T cell responses were equivalent to those of healthy control individuals.

Among individuals living with HIV infection, there is an at-risk group that deserves special attention. It comprises so-called immunological non-responders (INR), individuals who control their viral loads after antiretroviral therapy but only partially recover their CD4 T-lymphocyte count.

"Our study shows that these INRs may need a booster dose 28 days after the first vaccination to generate an efficient T cell response and thus be protected against monkeypox," explains Robert Güerri, the Hospital del Mar clinician who coordinated the vaccination study and is also an associate professor at UPF. Together, the new findings underscore the importance of specific studies on the immune response among people with HIV, especially those with lower CD4 .

Vaccine administration routes modulate the immune response

Before the monkeypox outbreak in the spring of 2022, the JYNNEOS vaccine was administered subcutaneously to protect the population. However, due to the increased vaccine demands, in August 2022, American and European health authorities proposed the intradermal administration route of the JYNNEOS vaccine.

Via this route, the vaccine is released into the upper layer of the skin, where many immune cells are located. Most importantly, this procedure extends the available vaccine doses by a factor of five, increasing vaccine availability without compromising its efficacy.

In contrast to the T-cell response of HIV-1-infected individuals who received the JYNNEOS vaccine subcutaneously, all individuals who received the vaccine intradermally generated a significant T-cell response. Therefore, intradermal vaccination was more effective in activating specific antiviral immunity.

"Our results clearly support the proposed dose-sparing vaccination route also for the protection of immunocompromised individuals who need the vaccine the most," adds Andreas Meyerhans, an ICREA researcher and UPF full professor, who coordinated the experimental part of the study.

This study provides an early indication of how best to proceed with preventive vaccination against monkeypox in a group of individuals at high risk of infection. However, further studies should confirm and expand on the observations derived from a small number of vaccinated individuals.

More information: Marta Sisteré‐Oró et al, Pan‐pox‐specific T‐cell responses in HIV‐1‐infected individuals after JYNNEOS vaccination, Journal of Medical Virology (2023). DOI: 10.1002/jmv.29317

Citation: Study: Smallpox vaccine efficiently induces immunity against mpox virus infection in people living with HIV (2024, January 12) retrieved 18 May 2024 from
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