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JOSÉ ANTONIO CABEZAS FERNÁNDEZ DEL CAMPO AN. R. ACAD. NAC. FARM.

humano de 1918 parecen indicar su vinculación con ambos orígenes (aviar y por-
cino), aunque aún faltan por ser precisados algunos aspectos.

Palabras clave: Gripe (1918-19).—Gripe aviar.—Hemaglutinina.—Neuramini-
dasa (= sialidasa).

ABSTRACT

The horrible influenza pandemic (erroneously named «Spanish influenza») re-
sulted in more than 20 million deaths. Knowledge about the virus that caused this
pandemic has improved remarkably in about the last twenty years due to two
factors: 1. The availability of new analytical techniques, more sensitive and specific
than previous procedures, that have been used to study human samples maintai-
ned in permafrost or kept in formalin-fixed, paraffin-embedded blocks; 2. The
occurrence in the last few years of influenza outbreaks in birds, caused by viruses
with certain characteristics similar to those considered as typical of the 1918-19
influenza virus. The mutations of few aminoacids in the virus hemagglutinin active
site could modify the binding specificity with receptors (N-acetylneuraminic acid
terminal residues) of the host cell. Thus, certain avian viruses may have achieved
the property of binding to cells of different species (pigs, humans) and may have
become immune to previously formed antibodies. The genetic, structural, etc.,
characteristics of hemagglutinin and neuraminidase (= sialidase) of the 1918-19
virus seem to show their connection with both avian and porcine viruses, although
some features should receive further study.

Key words: Influenza (1918-19).—Avian influenza.—Hemagglutinin.—Neura-
minidase (= sialidase).

1. INTRODUCCIÓN

Algunos estudios iniciados hacia 1950 y trabajos experimenta-
les más profundos realizados desde mediados de la década de 1990
han permitido en los últimos meses avanzar notablemente en el
conocimiento del virus de la famosa gripe que asoló prácticamente
a todo el mundo en 1918-19, causando una cifra de muertos com-
prendida entre los 20 y los 40 millones: Fue la impropiamente deno-
minada «gripe española».

Dos motivos han influido en el renovado interés por este estudio:
uno de ellos ha sido el hecho de que se ha podido disponer, desde

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