ĐÁNH GIÁ ĐỘC LỰC CỦA CHỦNG VIRUS DỊCH TẢ LỢN CHÂU PHI TÁI TỔ HỢP QUA ĐƯỜNG TIẾP XÚC GIỮA LỢN KHỎE VÀ LỢN GÂY BỆNH THỰC NGHIỆM BẰNG ĐƯỜNG MŨI

The emergence of recombinant ASFV strains with genetic characteristics of both genotype I and genotype II (rASFV I/II) in Vietnam since 2023 poses a major challenge for disease control, especially given the limited protective efficacy of current vaccines. This study aimed to evaluate the virulence and transmission potential of the recombinant ASFV strain VNUA/rASFV/HD1/23 using an experimental infection model by intranasal inoculation and natural contact exposure. The results showed that pigs directly inoculated with the virus developed acute clinical disease with a 100% mortality rate (3/3). Death occurred between the 5th and 12th day after infection (average 8 days). In the contact group, the first pig died on the 14th day after exposure. Typical clinical signs included high fever (> 40°C), anorexia, lethargy, and restricted mobility. Gross pathological findings in the infected pigs were consistent with acute ASF, characterised by splenomegaly with friability, haemorrhagic lymph nodes, and marked haemorrhage and congestion in the lungs, kidneys, intestines, and stomach. These results confirm the high virulence and transmissibility of the rASFV I/II strain.