Similar humoral immune responses against the SARS-CoV-2 spike protein in HIV and non-HIV individuals after COVID-19.

Dear editor

We have read with interest the article of Venturas et al., who found persons living with HIV (PWH) are not at higher risk of moderate or severe COVID-19 than the general population. The immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in PWH is a matter of controversy and intense research, as HIV infection may impair the immune response to SARS-CoV-2. High levels of neutralizing antibodies against SARS-CoV-2 spike (S) protein are associated with less severe disease and a good prognosis in COVID-19. These antibodies against the SARS-CoV-2 S protein block the virus union to its cellular receptor, the angiotensin-converting enzyme 2 (ACE2) receptor.

Thus, it is critical to determine whether the anti-SARS-CoV-2 neutralizing antibody response is impaired in PWH. This study aimed to characterize plasma antibodies against SARS-CoV-2 S protein in PWH and CTRLs recovered from COVID-19.

We performed a cross-sectional study in 91 PWH from the Cohort of the Spanish HIV Research Network (CoRIS) seropositive for SARS-CoV-2 and with plasma specimens collected from April 1, 2020, to September 30, 2020. We also included HIV-uninfected CTRLs seropositive for SARS-CoV-2 with plasma specimens stored in the National center for Microbiology Instituto de Salud Carlos III. Both groups were matched for age and time since initiation of symptoms and were not vaccinated against SARS-CoV-2. The Ethics Committee of Hospital General Universitario Gregorio Marañón approved the study (Ref# 162/20).

Blood samples were collected by venipuncture in EDTA tubes and were sent the same day to the Spanish HIV BioBank, where plasma samples were obtained and stored at −80 °C. These samples were sent to the Instituto de Salud Carlos III for its analysis. We used immunoassays to evaluate the antibody titer against the SARS-CoV-2 S protein, which gives us the area under the curve (AUC) of IgG, IgM, and IgA titration curves. Besides, we assayed the capacity of the antibodies to inhibit the binding of the soluble ACE2 receptor to S protein (see Supplemental file 1).

The differences between groups were calculated by the Mann-Whitney U test for continuous variables and the Chi-square test or Fisher's exact test for categorical variables. Generalized Linear Models (GLM) with a gamma distribution (log-link) adjusted by age, gender, and COVID-19 disease severity were used to evaluate the differences in plasma anti-SARS-CoV-2 S protein antibody levels (IgG, IgM, and IgA) between groups. The inhibition of ACE2 binding to the S protein (inhibition percentage, y-axis) and the titers of plasma anti-SARS-CoV-2 S protein antibodies (sum of AUCs of IgG, IgM, and IgA titration curves, x-axis) were plotted according to a semilog line, and Pearson's correlation coefficient (r) was calculated. Then, GLM tests were used to assess if regression slopes in PWH and CTRLs were differents by analyzing the interaction between the groups (PWH vs. CTRLs) with the sum of AUCs and inhibition percentages. Statistical analysis was performed with GraphPad Prism 9.0 (GraphPad Software, Inc., San Diego, CA, USA) and IBM SPSS Statistics 25.0 (SPSS INC, Armonk, NY, USA). The level of significance was two-tailed and defined as p < 0.05 (two-tailed).

The study population included 91 PWH – fully described elsewhere – and 21 CTRLs, whose characteristics are shown in Table 1 . Concerning COVID-19, 92.3% PWH had asymptomatic or mild COVID-19 disease, 7.7% were hospitalized, and the median time from symptoms to plasma collection was 11 weeks. CTRLs had similar characteristics to PWH, except for gender.

Table 1

Epidemiological and clinical characteristics of SARS-CoV-2 infected patients.

Variable	Control group	HIV group	p-value
No.	21	91
Demographic data
Male sex at birth – No./with data (%)	13 (61.9%)	85 (93.4%)	< 0.001
Age - Median (Q1; Q3) – yr.	42.3 (38.9; 48.8)	44.2 (36.8; 51.6)	0.902
COVID-19 data
Severity status (asymptomatic or mild) – No./with data (%)	18 (85.7%)	84 (92.3%)	0.277
Hospital admission – No./with data (%)	3 (14.3%)	7 (7.7%)	0.340
Time from symptoms - Median (Q1; Q3) – wk.	12.3 (11.1; 19.7)	11 (8.1; 15.4)	0.106
Oxygen-therapy – No./with data (%)	3 (14.3%)	6 (6.6%)	0.340
HIV infection data
Mechanism of HIV acquisition – No./with data (%)
Men having sex with men	-	68 (74.7%)	-
Heterosexual	-	20 (22%)	-
Injection drug use	-	1 (1.1%)	-
Other	-	2 (2.2%)	-
Age of HIV diagnosis - Median (Q1; Q3) – yr.	-	36.4 (28.1; 43.6)	-
Time with HIV infection - Median (Q1; Q3) – yr.	-	6.2 (3.3; 11.5)	-
Prior AIDS-defining conditions – No./with data (%)	-	11 (12.1%)	-
Age - Median (Q1; Q3) – yr.	-	45 (36.9; 46.9)	-
Last CD4+ count
Median (Q1; Q3) - cells/mm3	-	696.5 (491.5; 939)	-
Distribution – No./with data (%)
< 350	-	9/84 (10.7%)	-
350–499	-	13/84 (15.5%)	-
≥ 500	-	62/84 (73.8%)	-
Last HIV-RNA load ≤ 50 copies/mm3 – No./with data (%)	-	80 (94.1%)	-
Antiretroviral therapy – No./with data (%)	-	88 (96.7%)	-
Antiretroviral therapy (N[t]RTI backbone) – No./with data (%)
TAF/FTC	-	40 (44%)	-
ABC/3TC	-	25 (27.5%)	-
TDF/FTC	-	5 (5.5%)	-
Antiretroviral therapy (third drug)
NNRTI	-	48 (52.7%)	-
Protease inhibitor	-	4 (4.4%)	-
Integrase inhibitor	-	51 (56%)	-

Abbreviations: PWH. People with HIV; Q1. 1st quartile; Q3. 3rd quartile; N(t)RTI. nucleoside/nucleotide reverse transcriptase inhibitors; TAF. tenofovir alafenamide; FTC. emtricitabine; ABC. abacavir; 3TC. lamivudine; TDF; tenofovir disoproxil fumarate; NNRTI. non-nucleoside reverse transcriptase inhibitors.

No significant differences were found between groups in plasma levels of different classes of immunoglobulins against SARS-CoV-2 S protein [IgG (p = 0.414; Fig. 1 A), IgM (p = 0.862; Fig. 1B), and IgA (p = 0.134; Fig. 1C)], and percentages of inhibition of ACE2 binding to the S protein (p = 0.237; Fig. 1D). Adjusted regression analysis also found no significant differences (Supplemental Table 1). Furthermore, we found solid and similar correlations between total plasma antibody titers against SARS-CoV-2 S protein and the percentage of inhibition of ACE2 binding to the S protein in CTRLs (r = 0.580; p = 0.005; Fig. 1E) and PWH (r = 0.548; p < 0.001; Fig. 1F). No differences were found between the regression slopes of the two study groups (p = 0.849).

Fig. 1

Plasma levels of antibody against SARS-CoV-2 S protein (A–C) and percentages of inhibition of ACE2 receptor binding to the S protein (D). Correlation between antibody levels against SARS-CoV-2 S protein (sum of the AUC of IgG, IgM, and IgA) and percentages of inhibition of ACE2 receptor binding to the S protein (E and F).

Statistics: Differences were calculated by the Mann-Whitney U test, and medians were represented by a horizontal bar. Correlation analysis was performed using the Pearson test.

Abbreviations: AUC, the area under the curve; ACE2, angiotensin-converting enzyme 2; CTRLs, HIV-uninfected patients, PWH, persons living with human immunodeficiency virus; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus; IgG, anti-SARS-CoV-2 S IgG; IgM, anti-SARS-CoV-2 S IgM; IgA, anti-SARS-CoV-2 S IgA.

Several studies have reported that PWH usually shows poor antibody response to other viruses or viral vaccines[5], [6] – , raising concerns about whether they can mount an adequate humoral response against SARS-CoV-2. This issue is relevant since high antibody titers against the SARS-CoV-2 S protein correlate with virus neutralization and protection. Our study shows that PWH and CTRLs who recovered from COVID-19 display a similar antibody response against the S protein. To detect neutralizing antibodies, we used a stabilized trimeric S protein in its native pre-fusion conformation. The suitability of our assay was confirmed by the strong correlation between the antibody titers and their capacity to inhibit the interaction S protein-ACE2 receptor.

Our data agree with recently published results showing comparable anti-SARS-CoV-2 neutralizing antibody levels between PWH under effective antiretroviral therapy (ART) and HIV-uninfected individuals , . Succesful HIV suppression seems to be crucial for developing an adequate humoral immune response. In our study, almost all HIV patients analyzed were on ART, with good clinical, virological, and immunological control, which may have contributed to similar anti-SARS-CoV-2 antibody titers between PWH and CTRLs. We analyzed the antibody titers against the SARS-CoV-2 S protein and percentages of inhibition of ACE2 binding to the S protein according to CD4+ strata (< 350, 350–500, > 500 cells/mm3), and we did not find significant differences (data not shown). In contrast, lower neutralizing antibody titers against SARS-CoV-2 were found in PWH than in HIV-uninfected individuals recovering from COVID-19 by Spinelli et al., although its sample size was three times lower than in our study. Differences in the characteristics of the study cohorts (sample size, ethnicity, age, sex, COVID-19 severity, percentage of people with unsuppressed viral loads, among others), study design, or assays for antibody characterization may explain these conflicting results.

In conclusion, no differences in quantitative and qualitative SARS-CoV-2-specific immune humoral response were found between well-controlled PWH and CRTLs after recovery from COVID-19. This finding suggests that PWH are not an at-risk population for this infection and are potentially good vaccination responders.

Contribution

Study conception and design: Salvador Resino, Juan Berenguer, and Isidoro Martínez.

Acquisition of data: all authors.

Laboratory procedures: María Martín-Vicente, and María José Muñoz-Gómez.

Analyses and interpretation of data: Salvador Resino and Isidoro Martínez.

Drafting the article: Salvador Resino and Isidoro Martínez.

Critical revision of the article: Juan Berenguer.

Funding acquisition: Salvador Resino and Juan Berenguer.

All authors have read and approved the final manuscript.

Declaration of Competing Interest

The authors declare that they have no competing interests.