Actinobacillus pleuropneumoniae is an important pig pathogen that is responsible for swine pleuropneumonia, a highly contagious respiratory infection. Knowledge of the importance, composition and structural determination of the major antigens involved in virulence provides crucial information that could lead to the development of a rationale for the production of specific serodiagnostic tools as well as vaccine development. Thus, efforts have been devoted to study mainly A. pleuropneumoniaevirulence determinants with special emphasis on the Apx toxins (for A. pleuropneumoniaeRTX toxins). In comparison, little attention has been given to the surface polysaccharides, which include capsular polysaccharides (CPS) and cell-wall lipopolysaccharides (LPS). Here, we review current knowledge on CPS and LPS of A. pleuropneumoniae used as diagnostic tools to monitor the infection and as immunogens for inclusion in vaccine preparations for animal protection.

The objective of this article is to summarize the current state of knowledge of the complex interaction of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine pulmonary intravascular macrophages (PIMs). PIMs play an important role in pulmonary surveillance, and in the past few years we have investigated their role in PRRSV infection. PRRSV antigens and nucleic acids have been demonstrated in PIMs both in vitro and in vivo. Examination of cultured PIMs infected with PRRSV revealed the accumulation of viral particles in the smooth-walled vesicles. PRRSV-infected PIMs in vitro yielded a virus titer similar to pulmonary alveolar macrophages. PRRSV infection induces either apoptosis or cell lysis of PIMs. The in vitro bactericidal activity of PRRSV-infected PIMs is significantly decreased. Phagocytic activity of PIMs, as measured by pulmonary copper clearance, is significantly decreased in PRRSV-infected pigs. This evidence supports the hypothesis that PRRSV-induced damage to PIMs results in increased susceptibility to bacteremic diseases. Recent studies with PRRSV and Streptococcus suis coinfection confirmed that PRRSV predisposes pigs to S. suis infection and bacteremia. These results could explain the increase in bacterial respiratory diseases and septicemias observed in PRRSV-infected pigs.

The control of several infectious diseases of animals by vaccination is perhaps the most outstanding accomplishment of veterinary medicine in the last century. Even the eradication of some pathogens is in sight, at least in some parts of the world. However, infectious diseases continue to cost millions of dollars to the livestock industry. One of the reasons for the failure to control certain pathogens is the limited emphasis placed on cell-mediated immunity (CMI) in the design of vaccines against these pathogens. Traditionally, vaccine-induced immunity has been studied in relation to antibody-mediated protection. More recent studies, however, have focused on understanding CMI and developing means of inducing CMI. This review focuses on recent advances made in the study of CMI in general and of cytotoxic T lymphocytes in particular. Parallels from studies in human and mouse immunology are drawn in order to point out implications to bovine immunology, specifically for immunity against bovine herpesvirus 1.

Swine vesicular disease is a highly contagious disease of pigs that is caused by an enterovirus of the family Picornaviridae. The virus is a relatively recent derivative of the human coxsackievirus B5, with which it has high molecular and antigenic homology. The disease is not severe, and affected animals usually show moderate general weakening and slight weight loss that is recovered in few days, as well as vesicular lesions in the mucosa of the mouth and nose and in the interdigital spaces of the feet. However, the similarity of these lesions to those caused by foot-and-mouth disease virus has led to the inclusion of this virus in list A of the Office International des Epizooties. The disease has been eradicated in the European Union except in Italy, where it is considered endemic in the south. Nevertheless, as occasional outbreaks still appear and must be eliminated rapidly, European countries are on the alert and farms are monitored routinely for the presence of the virus. This circumstance has led to a considerable effort to study the pathology of the disease and the molecular biology and antigenicity of the virus, and to the development of optimized methods for the diagnosis of the infection.

Sheep and goats occupy a premier place in the livestock industry and contribute significantly to the world economy. Their populations are threatened by a number of health hazards, among the most notable of which are goat pox and sheep pox. These diseases inflict substantial losses in terms of reduced productivity and lower quality of wool and leather. They pose a major obstacle to the intensive rearing of sheep and goats and considerably hamper international trade. A comprehensive knowledge of goat pox and sheep pox would help in the diagnosis, prevention and control as well as the management of these diseases in a proper and effective manner. Although the two diseases are easily identified from the clinical signs and host species affected, laboratory tests are needed for confirmation. A battery of simple but highly efficient diagnostic methods and reagents is available for goat pox and sheep pox. However, the best way to control these diseases is the prophylactic immunization of all susceptible animals with a potent and efficacious vaccine, especially in areas where these diseases are endemic.