Strains of Virus of Foot-and-Mouth Disease Recovered from Outbreaks in Mexico. Identification

Abstract

These observations were made during the examination of samples of virus which were recovered from cattle during an epizootic in Mexico. It was reported that foot-and-mouth disease existed in Mexico in the last quarter of 1946 and now in June, 1948, fresh outbreaks of the disease are still occurring. Up to the present 13 separate samples of virus from Mexico have been examined at this Institute and as will be seen from the results recorded all of them could be classified in the main Vallée A immunological type group. After identification these virus samples were termed strains of the virus of foot-and-mouth disease. For the purpose of future reference a list is appended with the dates of collection and reported geographical origin:

MP-Puebla, Dec. 23, 1946

MPB-Puebla, Jan. 1, 1947

MC-Camarones, Jan. 21

MSL-San Lorenzo, Jan. 31

M.1-Jalisco, Oct. 7

M.2-Cuerrero, Oct. 11

M.3-Toluca, Sept. 20

M.4-Lerma, Sept. 30

M.5-El Sal to, Jalisco, Nov.

M.6-El Bajo, Jalisco, Mar. 19, 1948

M.7-Guzman, Apr. 12

M.8-Zapotiltic, Apr. 13

M.9-Zapotiltic, Apr. 13

So far the antigenic behavior of only 2 of the virus strains MP (23.12.46) and M.l (7.10.47) have been investigated in some detail but further work is proceeding on the Mexican strains of virus and the results will be reported later.

These studies on antigenicity which are reported in other papers of the present series include complement fixation, serum neutralization and vaccination experiments.

Identification of infective agent and general immunological type classification.

1. Animal Species Susceptibility.

(a) Inoculation of cattle.

The respective inoculation of suspensions of the thirteen samples of material received intradermally into the tongues of cattle has produced in every case a generalized vesicular disease resembling, in its general characteristics, foot-and-mouth disease.

(b) Inoculation of horses and donkeys. Suspensions of some of the samples of material received were inoculated intradermally into the tongues of horses and donkeys as follows:

M.l-2 horses and 2 donkeys

M.2-2 horses

M.3-2 horses

M.4-2 donkeys

MP-2 donkeys and contrary to what might have happened if the virus of vesicular stomatitis had been involved, no lesions were observed in any instance.