Hanta Virus

 Hanta Virus

    Hanta Virus came to me as a new disease, a new problem, a new phenomenon when I heard (on Sunday 3rd May 2026) of the outbreak on the Dutch cruise ship MV Hondius. It appear that the first death on board occurred on 11th April in mid Atlantic 11 days after leaving Argentina. The body was evacuated to St. Helena on 24th April and repatriated to Holland with the wife of the dead man; by today (5th May) the wife had also died. 

    But Hanta Virus is not all that new. Several people knew already that the Hollywood actor Gene Hackman and his wife probably both died of the virus in February 2025 [2]. And the US Department of Health has been tracking known cases of the pulmonary form of the disease (Hantavirus pulmonary syndrome, HPS) since 1993 when there was a cluster of cases in the 'Four-Corners' area of the United States (Arizona, Colorado, New Mexico, and Utah). In the 30 years between 1993, when monitoring in the States began, and 2023, there were 890 cases of hantavirus disease reported. The fatality rate was the alarming 35% [3]. 

    But the Hanta Virus family of viruses seems to be a great deal older than that. They have been known to science since 1978 [4], and seem to have co-evolved with their rodent hosts over a period of many millions of years [5]. While showing considerable specificity for their host rodent, be it the deer mouse in the the mid-west United States, which carries a virus that focuses on the lungs, or the bank vole and the common rat both of which carry viruses that attack the kidney (causing Hemorrhagic Fever with Renal Syndrome, HFRS), we see from the outbreak on the cruise ship MV Hondius that the virus can occasionally jump host, to another rodent, or to humans [5].

    Structurally, viruses of the Hanta Virus family are small spheres with a single membrane coat covered in glycoprotein spikes through which the virion attaches to a target protein in host cell membranes, usually integrins, but not always. (Integrins are integral membrane proteins, present on the surface of all animal cells, always present as hetero-dimers, each typically having a small C-terminal domain inside the cell and a larger, glycosylated, outer N-terminal domain. They typically function both as physical attachment points and signal-transduction molecules.)

    The viral genome comprises three small pieces of single stranded RNA in negative orientation [6]. (In COVID the single-stranded RNA is in positive orientation.)

(Added 7th May 2026)

    The three pieces of ssRNA that constitute the genome are called large, medium and small or L, M, S.

Large, containing 6.8 – 12 kilobases (kb), codes for the RNA-dependent RNA polymerase. A recent paper in Nature [7] describes its structure in considerable detail and proposes a possible mode of action. 

Medium, containing between 3.6 and 3.7 kb, codes for the two glycoproteins, Gc and Gn, which, as hetero-dimers, form the coat, the spikes and the docking mechanism.

Small, 1.7 - 2.1 kb, when copied, produces a positive stranded messenger RNA that codes for the Nucleocapsid protein whose role is to coat the single negative strands of these three genomic segments [6].

    The symptomless 'incubation' period seems to be longish and variable; 1-2 week but exceptionally up to 8 weeks. This may be a feature of negative-single-stranded RNA viruses, and the complex process of activating the polymerase described by Durieux Trouilleton et al. [7]. 

I shall add to this article as I acquire more information. 

References:

[1] Guardian: Ashifa Kassam and agencies, Tue 5 May 2026 02.52 BST

[2] Ewan Somerville, BBC News, Published, 15 April 2025

[3] https://www.cdc.gov/hantavirus/about/index.html

[4] Edward C Holmes, Yong-Zhen Zhang, "The evolution and emergence of hantaviruses" https://doi.org/10.1016/j.coviro.2014.12.007

[5] CDC – https://www.cdc.gov/hantavirus/about/index.html

[6] Hanta Virus – An Overview. March 23, 2022 by Sagar Aryal, PhD. https://microbenotes.com/hanta-virus/

[7] Durieux Trouilleton, Q., Barata-García, S., Arragain, B. et al. "Structures of active Hantaan virus polymerase uncover the mechanisms of Hantaviridae genome replication". Nat Commun 14, 2954 (2023). https://doi.org/10.1038/s41467-023-38555-w

(Comments are welcome to Cawstein@gmail.com)