Interrelations between viral load and cellular immunity in patients with COVID-19 of varying severity

Assessment of viral load levels in various biological samples taken from the respiratory tract can be an indicator of an ongoing process of active viral replication and may be used to monitor severe respiratory viral infections. The study of the relationship between SARS-CoV-2 viral load and immunological laboratory parameters is an important step in the search for clinical markers of COVID-19.

The aim of this research was to quantify viral load in patients with COVID-19 and to identify the relation-ship between viral load and changes in the parameters of the cellular component of the immune system.

A laboratory examination was carried out on 74 patients diagnosed with COVID-19, they were divided into 3 groups based on the severity of the disease: mild, moderate, severe. Total viral load in clinical samples was determined by the number of SARS-CoV-2 RNA copies per 100 copies of the reference RNaseP gene.     A comprehensive assessment of the cellular component of the immune system was performed using flow cytometry and direct monoclonal antibodies, and the IL-6, and C-reactive protein concentrations were determined.

We revealed a relationship between the development of serious clinical conditions in the patients with COVID-19, and the levels of viral load. High levels of viral RNA in biological samples correlate with main indicators of the T cell component of the immune system associated with disease severity. In a subgroup of patients with an extremely high viral load, strong positive correlations were found between the relative numbers of cytotoxic lymphocytes (CD3⁺CD8⁺), activated T lymphocytes (CD3⁺HLA-DR⁺), as well as absolute and relative numbers of activated B lymphocytes and NK cells (CD3-CD25⁺).

Laboratory monitoring of the cellular component of the immune system, along with the assessment of viral loads, should improve  early assessment of clinical condition in the patients with COVID-19. Changes   in expression levels of activation markers on immune cells can be potentially viewed as indicators of recovery during COVID-19.

1. Bao J., Li C., Zhang K., Kang H., Chen W., Gu B. Comparative analysis of laboratory indexes of severe and non-severe patients infected with COVID-19. Clin. Chim. Acta, 2020, Vol. 509, pp. 180-194.

2. Bermejo-Martin J.F., Almansa R., Menéndez R., Mendez R., Kelvin D.J., Torres A. Lymphopenic community acquired pneumonia as signature of severe COVID-19 infection. J. Infect., 2020, Vol. 80, no. 5, pp. e23-e24.

3. Bermejo Martin J.F., González-Rivera M., Almansa R., Micheloud D., Tedim A.P., Domínguez-Gil M., Resino S., Martín-Fernández M., Ryan Murua P., Pérez-García F., Tamayo L., Lopez-Izquierdo R., Bustamante E., Aldecoa C., Gómez J.M., Rico-Feijoo J., Orduña A., Méndez R., Fernández Natal I., Megías G., González-Estecha M., Carriedo D., Doncel C., Jorge N., Ortega A., de la Fuente A., del Campo F., Fernández-Ratero J.A., Trapiello W., González-Jiménez P., Ruiz G., Kelvin A.A., Ostadgavahi A.T., Oneizat R., Ruiz L.M., Miguéns I., Gargallo E., Muñoz I., Pelegrin S., Martín S., Olivares P.G., Cedeño J.A., Albi T.R., Puertas C., Berezo J.Á., Renedo G., Herrán R., Bustamante-Munguira J., Enríquez P., Cicuendez R., Blanco J., Abadia J., Barquero J.G., Mamolar N., Blanca-López N., Valdivia L.J., Caso B.F., Mantecón M.Á., Motos A., Fernandez-Barat L., Ferrer R., Barbé F., Torres A., Menéndez R., Eiros J.M., Kelvin D.J. Viral RNA load in plasma is associated with critical illness and a dysregulated host response in COVID-19. Crit. Care, 2020, Vol. 24, no. 1, 691. doi:10.1186/s13054-020-03398-0.

4. Cevik M., Bamford C.G., Ho A. COVID-19 pandemic-a focused review for clinicians. Clin. Microbiol. Infect., 2020, Vol. 26, no. 7,pp. 842-847.

5. Chen X., Zhao B., Qu Y., Chen Y., Xiong J., Feng Y., Men D., Huang Q., Liu Y., Yang B., Ding J., Li F. Detectable serum severe acute respiratory syndrome coronavirus 2 viral load (RNAemia) is closely correlated with drastically elevated interleukin 6 level in critically Ill patients with coronavirus disease 2019. Clin. Infect. Dis., 2020, Vol. 71, no. 8, pp. 1937-1942.

6. Cheng P.K., Wong D.A., Tong L.K., Ip S.M., Lo A.C., Lau C.S., Yeung E.Y., Lim W.W. Viral shedding patterns of coronavirus in patients with probable severe acute respiratory syndrome. Lancet, 2004, Vol. 363, pp. 1699-1700.

7. Giamarellos-Bourboulis E.J., Netea M.G., Rovina N., Akinosoglou K., Antoniadou A., Antonakos N., Damoraki G., Gkavogianni T., Adami M.E., Katsaounou P., Ntaganou M., Kyriakopoulou M., Dimopoulos G., Koutsodimitropoulos I., Velissaris D., Koufargyris P., Karageorgos A., Katrini K., Lekakis V., Lupse M., Kotsaki A., Renieris G., Theodoulou D., Panou V., Koukaki E., Koulouris N., Gogos C., Koutsoukou A. Complex immune dysregulation in COVID-19 patients with severe respiratory failure. Cell Host Microbe, 2020, Vol. 27, no. 6, pp. 992-1000.e3.

8. He X., Lau E.H., Wu P., Deng X., Wang J., Hao X., Lau Y.C., Wong J.Y., Guan Y., Tan X., Mo X., Chen Y., Liao B., Chen W., Hu F., Zhang Q., Zhong M., Wu Y., Zhao L., Zhang F., Cowling B.J., Li F., Leung G.M. Temporal Dynamics in viral shedding and transmissibility of COVID-19. Nat. Med., 2020, Vol. 26, no. 5, pp. 672-675.

9. Hung I.F., Cheng V.C., Wu A.K., Tang B.S., Chan K.H., Chu C.M., Wong M.M., Hui W.T., Poon L.L., Tse D.M., Chan K.S., Woo P.C., Lau S.K., Peiris J.S., Yuen K.Y. Viral loads in clinical specimens and SARS manifestations. Emerg. Infect. Dis., 2004, Vol. 10, no. 9, pp. 1550-1557.

10. Laing A.G., Lorenc A., del Molino del Barrio I., Das A., Fish M., Monin L., Muñoz-Ruiz M., McKenzie D.R., Hayday T. S., Francos-Quijorna I., Kamdar S., Joseph M., Davies D., Davis R., Jennings A., Zlatareva I., Vantourout P., Wu Y., Sofra V., Cano F., Greco M., Theodoridis E., Freedman J.D., Gee S., Chan J.N.E., Ryan S., Bugallo-Blanco E., Peterson P., Kisand K., Haljasmägi L., Chadli L., Moingeon P., Martinez L., Merrick B., Bisnauthsing K., Brooks K., Ibrahim M.A.A., Mason J., Lopez Gomez F., Babalola K., Abdul-Jawad S., Cason J., Mant C., Seow J., Graham Carl., Doores K.J., Di Rosa F., Edgeworth J., Shankar-Hari M., Hayday A.C. Author Correction: A dynamic COVID-19 immune signature includes associations with poor prognosis. Nat Med., 2020, Vol. 26, no. 12, 1951. doi: 10.1038/s41591-020-01186-5.

11. Leisman D.E., Ronner L., Pinotti R., Taylor M.D., Sinha P., Calfee C.S., Hirayama A.V., Mastroiani F., Turtle C.J., Harhay M.O., Legrand M., Deutschman C.S. Cytokine elevation in severe and critical COVID-19: a rapid systematic review, meta-analysis, and comparison with other inflammatory syndromes. Lancet Respir. Med., 2020, Vol. 8, no. 12, pp. 1233-1244.

12. Magleby R., Westblade L.F., Trzebucki A., Simon M.S., Rajan M., Park J., Goyal P., Safford M.M., Satlin M.J. Impact of Severe Acute Respiratory Syndrome Coronavirus 2 Viral Load on Risk of Intubation and Mortality Among Hospitalized Patients With Coronavirus Disease 2019. Clini. Infect. Dis., 2021, Vol. 73, no. 11, pp. e4197-e4205.

13. Memish Z.A., Al-Tawfiq J.A., Makhdoom H.Q., Assiri A., Alhakeem R.F., Albarrak A., Alsubaie S., Al-Rabeeah A.A., Hajomar W.H., Hussain R., Kheyami A.M., Almutairi A., Azhar E.I., Drosten C., Watson S.J., Kellam P., Cotten M., Zumla A. Respiratory tract samples, viral load, and genome fraction yield in patients with Middle East respiratory syndrome. J. Infect. Dis., 2014, Vol. 210, no. 10, pp. 1590-1594.

14. Monneret G., Cour M., Viel S., Venet F., Argaud L. Coronavirus disease 2019 as a particular sepsis: a 2-week follow-up of standard immunological parameters in critically ill patients. Intensive Care Med., 2020, Vol. 46, no. 9, pp. 1764-1765.

15. Ohno Y., Kitamura H., Takahashi N., Ohtake J., Kaneumi S., Sumida K., Homma S., Kawamura H., Minagawa N., Shibasaki S., Taketomi A. IL-6 down-regulates HLA class II expression and IL-12 production of human dendritic cells to impair activation of antigen-specific CD4(+) T cells. Cancer Immunol. Immunother., 2016, Vol. 65, no. 2, pp. 193-204.

16. Pan Y., Zhang D., Yang P., Poon L.L.M., Wang Q. Viral load of SARS-CoV-2 in clinical samples. Lancet Infect. Dis,, 2020, Vol. 20, no. 4, pp. 411-412.

17. Peiris J.S.M., Chu C.M., Cheng V.C., Chan K.S., Hung I.F., Poon L.L., Law K.I., Tang B.S., Hon T.Y., Chan C.S., Chan K.H., Ng J.S., Zheng B.J., Ng W.L., Lai R.W., Guan Y., Yuen K Y., HKU/UCH SARS Study Group. Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study. Lancet, 2003, Vol. 361, no. 9371, pp. 1767-1772.

18. Rainer T.H., Lee N., Ip M., Galvani A.P., Antonio G.E., Wong K.T., Chan D.P., Ng A.W., Shing K.K., Chau S.S., Mak P., Chan P.K., Ahuja A.T., Hui D.S., Sung J.J. Features discriminating SARS from other severe viral respiratory tract infections. Eur. J. Clin. Microbiol. Infect. Dis., 2007, Vol. 26, no. 2, pp. 121-129.

19. Song C.Y., Xu J., He J.Q., Lu Y.Q. COVID-19 early warning score: a multi-parameter screening tool to identify highly suspected patients. medRxiv, 2020. doi: 10.1101/2020.03.05.20031906.

20. Venet F., Monneret G. Advances in the understanding and treatment of sepsis-induced immunosuppression. Nat. Rev. Nephrol., 2018, Vol. 14, no. 2, pp. 121-137.

21. Veyer D., Kernéis S., Poulet G., Wack M., Robillard N., Taly V., L’Honneur A. S., Rozenberg F., Laurent-Puig P., Bélec L., Hadjadj J., Terrier B., Péré H. Highly Sensitive Quantification of Plasma Severe Acute Respiratory Syndrome Coronavirus 2 RNA Sheds Light on its Potential Clinical Value. Clin. Infect. Dis., 2021, Vol. 73, no. 9, pp. e2890-e2897.

22. WHO. Laboratory testing for 2019 novel coronavirus (2019-nCoV) in suspected human cases. Interim guidance, Jan 17, 2020. Available at: https://www.who.int/publications-detail/laboratory-testing-for-2019-novelcoronavirus-in-suspected-humancases-20200117 (accessed Feb 11, 2020).

23. Yuan Y., Wang H., Zhao J., Jing N., Xu J., Li W., Ma B., Zhang J., Li G., Wang S., Li Y., Wang Y., Fan E., Li L. Severe Acute Respiratory Syndrome Coronavirus 2 Viral RNA Load Status and Antibody Distribution Among Patients and Asymptomatic Carriers in Central China. Front. Cell. Infect. Microbiol., 2021, Vol. 11, 559447. doi: 10.3389/fcimb.2021.559447.

24. Zaki A.M., van Boheemen S., Bestebroer T.M., Osterhaus A.D., Fouchier R.A. Isolation of a novel coronavirus from a man with pneumonia in Saudi Arabia. N. Engl. J. Med., 2012, Vol. 367, pp. 1814-1820.

25. Zhang W., Du R.H., Li B., Zheng X.S., Yang X.L., Hu B., Wang Y.Y., Xiao G.F., Yan B., Shi Z.L., Zhou P. Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routes. Emerg. Microbes Infect., 2020, Vol. 9, no. 1, pp. 386-389.

26. Zheng S., Fan J., Yu F., Feng B., Lou B., Zou Q., Xie G., Lin S., Wang R., Yang X., Chen W., Wang Q., Zhang D., Liu Y., Gong R., Ma Z., Lu S., Xiao Y., Gu Y., Zhang J., Yao H., Xu K., Lu X., Wei G., Zhou J., Fang Q., Cai H., Qiu Y., Sheng J., Chen Y., Liang T. Viral load dynamics and disease severity in patients infected with SARS-CoV-2 in Zhejiang province, China, January-March 2020: retrospective cohort study. BMJ, 2020, Vol. 369, m1443. doi:10.1136/bmj.m1443.

27. Zou L., Ruan F., Huang M., Liang L., Huang H., Hong Z., Yu J., Kang M., Song Y., Xia J., Guo Q., Song T., He J., Yen H.-L., Peiris M., Wu J. SARS-CoV-2 viral load in upper respiratory specimens of infected patients. N. Engl. J. Med., 2020, Vol. 382, pp. 1177-1179.